The serine proteases of Mycobacteria tuberculosis(Mtb)are important contributors to the process of bacterial invasion and its pathogenesis.In the present study,we systematically characterized the role of the Rv1043c p...The serine proteases of Mycobacteria tuberculosis(Mtb)are important contributors to the process of bacterial invasion and its pathogenesis.In the present study,we systematically characterized the role of the Rv1043c protein in Mycobacterium infection by purifying the Rv1043c protein in Escherichia coli and constructing a Mycobacterium smegmatis(Msg)strain overexpressing Rv1043c(Msg_Rv1043c).We found that Rv1043c had serine protease activity and localized to the surface of Mtb.We determined that the optimal pH and temperature for the Rv1043c serine protease were 9.0 and 45°C,respectively.Moreover,the serine protease activity of Rv1043c was enhanced by divalent metal ions of Ca^(2+)and Mg^(2+).Site-directed mutagenesis studies demonstrated that the serine 279 residue in Rv1043c plays a catalytic role.Additionally,mouse model studies confirmed that Rv1043c significantly enhanced the survival of Msg in vivo,induced pulmonary injury and lung cell apoptosis,and promoted the release of pro-inflammatory cytokines interleukin-1βand interleukin-6 in mice.This study presents novel insights into the relationship between mycobacterial serine protease and the pathogenesis of the disease.展开更多
Infection of plum bark necrosis stem pitting associated virus(PBNSPaV)has been reported in many Prunus species in several countries,causing significant economic losses.The very small proteins encoded by plant viruses ...Infection of plum bark necrosis stem pitting associated virus(PBNSPaV)has been reported in many Prunus species in several countries,causing significant economic losses.The very small proteins encoded by plant viruses are often overlooked due to their short sequences and uncertain significance.However,numerous studies have indicated that they might play important roles in the pathogenesis of virus infection.The role of small hydrophobic protein P6,encoded by the open reading frame 2 of PBNSPaV,has not been well explored.In this study,we amplified the P6 fragment from a PBNSPaV isolate by RT-PCR using specific primers and found that it is 174 bp long and encodes a protein of approximately 6.3 kD with a transmembrane domain.Subcellular localization analysis of P6 proteins in tobacco leaves showed that P6 localizes to the cytomembrane and nuclear membrane.To further clarify the pathogenicity of P6 proteins,we constructed a PVX-P6 expression vector by inserting the p6 fragment into a potato virus X(PVX)-based vector and transformed it into Agrobacterium tumefaciens GV3101.Infiltration of Nicotiana benthamiana(N.benthamiana)with the PVX vector-transformed A.tumefaciens led to slight mosaic symptoms at 14 days of post-inoculation.Meanwhile,infiltration with the PVX-P6 vector-transformed A.tumefaciens resulted in no significant symptoms.These results demonstrated that heterologous expression of P6 in N.benthamiana could not enhance the pathogenicity of PVX.Our study indicates that P6 may not be a potential pathogenic factor associate with the causing of symptoms,and the mode of action of PBNSPaV-P6 protein remains to be further studied.展开更多
Fusarium wilt is a common fungal disease in sesame caused by Fusarium oxysporum f.sp.sesami(FOS).To determine the toxin production profiles of the FOS isolates with different pathogenicity levels under various culture...Fusarium wilt is a common fungal disease in sesame caused by Fusarium oxysporum f.sp.sesami(FOS).To determine the toxin production profiles of the FOS isolates with different pathogenicity levels under various culture conditions,we assessed the content variation of fusaric acid(FA)and 9,10-dehydrofusaric acid(9,10-DFA)produced by the four representative FOS isolates.Results indicated that the concentration of FA reached to a maximum of 2848.66μg/mL in Czapek medium,while 9,10-DFA was mainly produced in Richard and Lowcarbon Richard medium.The concentration of 9,10-DFA on Richard culture medium varied from 0μg/mL to 716.89μg/mL.Of the five culture media used in this study,Czapek culture medium was the most conductive to produce FA.FA production was significantly affected by culture medium,culture time,and their interactions.Results suggest that there is no correlation between toxin production and pathogenicity level of FOS isolates.These findings provide key information for the mechanism analysis of FOS-sesame interaction and pathogen control.展开更多
[Objectives]The paper was to study molecular characterization,morphology and pathogenicity of Curvularia pseudobrachyspora,a new causal agent of leaf spot on banana.[Methods]Banana(Musa acuminate)leaves with streaks o...[Objectives]The paper was to study molecular characterization,morphology and pathogenicity of Curvularia pseudobrachyspora,a new causal agent of leaf spot on banana.[Methods]Banana(Musa acuminate)leaves with streaks or long ellipse-shaped lesions were sampled in an orchard of Danzhou City,Hainan Province,China in 2021.Fungus isolates were isolated from the diseased tissues and further identified as C.pseudobrachyspora based on morphological characteristics of colony,conidiophore and spore,phylogenetic analyses of the ITS region,GAPDH and TEF-1αgenes.[Results]In the pathogenicity test,the fungus re-isolated from inoculated leaves with necrotic lesions was identified morphologically and molecularly,fulfilling Koch's postulates.[Conclusions]C.pseudobrachyspora is a new pathogen causing leaf spot of banana in China and the world.展开更多
Peanut (Arachis hypogaea L.) late leaf spot is an important disease caused by Phaeoisariopsis personata (Berk. Et M. A Curt.). This fungus is responsible for the most damaging leaf spots in peanut production. The pres...Peanut (Arachis hypogaea L.) late leaf spot is an important disease caused by Phaeoisariopsis personata (Berk. Et M. A Curt.). This fungus is responsible for the most damaging leaf spots in peanut production. The present experiment was undertaken to evaluate the pathogenic variability of Phaeoisariopsis personata in Burkina Faso. To this end, detached leaves and healthy plants of three peanut varieties were inoculated. Isolates I3TF, I2TG and I1TK of the pathogen (10<sup>5</sup> conidia/ml), collected respectively in the western, central and eastern agroecological zones of country, were used. The inoculated leaves were kept in Petri dishes on moist blotting paper and stored in the laboratory during the experimental period. The inoculated plants were grown under glass in pots containing a mixture of sterilized sand and clay. The development of disease was monitored and severity was scored every 15 days using rating scale. The results obtained in the laboratory and in the greenhouse revealed that there is pathogenic variability in the isolates tested. Indeed, for each variety, the highest severity score was recorded in plants inoculated with isolate I3TF and the lowest severity score with isolate I1TG. In the laboratory the severity scores ranged from 6.76 to 8.80 in TS32-1, 6.18 to 8.29 in SH70P and 5.98 to 7.92 in PC79-79. In the greenhouse, the average severity scores ranged from 5.61 to 8.33 in TS32-1, from 5.19 to 8.00 in SH70P, from 4.90 to 7.50 in PC79-79. Thus, the variety TS32-1 was the most susceptible to all three isolates of the pathogen.展开更多
Biological nature of the bacterial pathogenicity phenomenon is based on the interaction of prokaryotic and eukaryotic organisms. The phenomenon is the poly-functional biological potency of germs that are realized by f...Biological nature of the bacterial pathogenicity phenomenon is based on the interaction of prokaryotic and eukaryotic organisms. The phenomenon is the poly-functional biological potency of germs that are realized by factors (determinants) of pathogenicity. Some fundamental biological functions are responsible for bacterial pathogenicity in a multi-cellular host organism: the adhesive function, the function of invasion and penetration into the cell, the function of evasion of host defense, and the damage function. The action of adhesion, invasion and evasionis directed to towards establishing an ecological niche in multi-cellular host while the aim of the damaging function is destruction of the environment.展开更多
AIM To explore the virulence and the potential pathogenicity of coccoid Helicobacter pylori (H. pylori) transformed from spiral form by exposure to antibiotic.METHODS Three strains of H. pylori, isolated from gastric ...AIM To explore the virulence and the potential pathogenicity of coccoid Helicobacter pylori (H. pylori) transformed from spiral form by exposure to antibiotic.METHODS Three strains of H. pylori, isolated from gastric biopsy specimens of confirmed peptic ulcer, were converted from spiral into coccoid from by exposure to metronidazole.Both spiral and coccoid form of H. pylori were tested for the urease activity, the adherence to Hep-2 cells and the vacuolating cytotoxicity to Hela cells, and the differences of the protein were analysed by SDS-PAGE and Western blot,The mutation of the genes including ureA, ureB,hpaA; vacA and cagA, related with virulence,was detected by means of PCR and PCR-SSCP.RESULTS In the coccoid H. pylori, the urease activity, the adherence to Hep-2 cells and the vacuolating cytotoxicity to Hela cells alldecreased. In strain F44, the rate and index of adherence reduced from 70.0% ± 5.3% to 33% ±5.1% and from 2.6 ±0.4 to 0.96 ±0.3 (P＜0.01),respectively. The invasion of coccoid H. pylori into Hep-2 cell could be seen under electronmicroscope. SDS-PAGE showed that the content of the protein with the molecular weight over Mr74 000 decreased, and the hybriditional signal in band Mr 125 000 weakened, while the band Mr 110000 and Mr63000 strengthened in coccoid H. pylori as shown in Western blot. The results of PCR were all positive, and PCR-SSCP indicated that there may exist the point mutation in gene hpaA or vacA.CONCLUSION The virulence and the proteins with molecular weight over Mr74 000 in coccoid H. pylori decrease, but no deletion exists in amplification fragments from ureA, ureB, hpaA,vacA and cagA genes, suggesting that coccoid H. pylori may have potential pathogenicity.展开更多
Obligate biotrophic fungi cause serious and widespread diseases of crop plants, but are challenging to investigate because they cannot be cultured in vitro. The two economically important groups of biotrophic fungi pa...Obligate biotrophic fungi cause serious and widespread diseases of crop plants, but are challenging to investigate because they cannot be cultured in vitro. The two economically important groups of biotrophic fungi parasitizing wheat are the rust and powdery mildew pathogens, but their obligate biotrophic lifestyles and pathogenicity mechanisms are not well understood at the molecular level. With the advent of next generation sequencing technology, increasing numbers of pathogen genomes are becoming available. Research in plant pathology has entered a new genomics era. This review summarizes recent progress in understanding the biology and pathogenesis of biotrophic fungal pathogens attacking wheat based on pathogen genomics. We particularly focus on the three wheat rust and the powdery mildew fungi in regard to genome sequencing, avirulence gene cloning, effector discovery, and pathogenomics. We predict that coordinated study of both wheat and its pathogens should reveal new insights in biotrophic adaptation, pathogenicity mechanisms,and population dynamics of these fungi that will assist in development of new strategies for breeding wheat varieties with durable resistance.展开更多
AIM To study the pathogenicity of hepatitis G virus (HGV) and observe the genesis and pathological process of hepatitis G.METHODS HGV-RNA in serum was detected by RT-PCR assay. The immunohistochemical assays of liver ...AIM To study the pathogenicity of hepatitis G virus (HGV) and observe the genesis and pathological process of hepatitis G.METHODS HGV-RNA in serum was detected by RT-PCR assay. The immunohistochemical assays of liver tissue were performed with HGV monocoloned antibody (McAb)expressed from the region of HGV NS5 nucleic acid sequence. The clinical and pathological data of 52 patients with hepatitis G were discussed. In animal experiment,the Chinese Rhesus monkeys were infected with the serum of a patient with HGV infection. And the dynamic changes in serology and liver histology of animals were observed.RESULTS One hundred and fifty-four patients with HGVRNA positive were selected from 1552 patients with various kinds of hepatitis. Of 154 patients with HGV infection, 52 were infected with HGV only, which accounted for 33.8% (52/154) and 102 with positive HGVRNA were super-infected with other hepatitis viruses,which accounted for 66.2% (102/154). The clinical and pathological observation showed that the acute and chronic hepatitis could be induced by HGV. The slight abnormality of transaminases ALT and AST in serum of monkeys lasted nearly 12 months and histological results showed a series of pathological changes.CONCLUSION HGV is a hepatotropic virus and has pathogenicty.展开更多
AIM:To test the pathogenicity of pseudorabies virus(PRV)variant HN1201 and compare its pathogenicity with a classical PRV Fa strain.METHODS:The pathogenicity of the newly-emerging PRV variant HN1201 was evaluated by d...AIM:To test the pathogenicity of pseudorabies virus(PRV)variant HN1201 and compare its pathogenicity with a classical PRV Fa strain.METHODS:The pathogenicity of the newly-emerging PRV variant HN1201 was evaluated by different inoculating routes,virus loads,and ages of pigs.The classical PRV Fa strain was then used to compare with HN1201 to determine pathogenicity.Clinical symptoms after virus infection were recorded daily and average daily body weight was used to measure the growth performance of pigs.At necropsy,gross pathology and histopathology were used to evaluate the severity of tissue damage caused by virus infection.RESULTS:The results showed that the efficient infection method of RPV HN1201 was via intranasal inoculation at 107 TCID50,and that the virus has high pathogenicity to 35-to 127-d old pigs.Compared with Fa strain,pigs infected with HN1201 showed more severe clinical symptoms and pathological lesions.Immunochemistry results revealed HN1201 had more abundant antigen distribution in extensive organs.CONCLUSION:All of the above results suggest that PRV variant HN1201 was more pathogenic to pigs than the classical Fa strain.展开更多
Bacterial blight, caused by Xanthomonas oryzae pv. oryzae(Xoo), is one of the most destructive diseases of rice(Oryza sativa L.) worldwide. The type III secretion system(T3SS) of Xoo, encoded by the hrp(hypersensitive...Bacterial blight, caused by Xanthomonas oryzae pv. oryzae(Xoo), is one of the most destructive diseases of rice(Oryza sativa L.) worldwide. The type III secretion system(T3SS) of Xoo, encoded by the hrp(hypersensitive response and pathogenicity) genes, plays critical roles in conferring pathogenicity in host rice and triggering a hypersensitive response(HR) in non-host plants. To investigate the major genes conferring the pathogenicity and avirulence of Xoo, we previously constructed a random Tn5-insertion mutant library of Xoo strain PXO99A. We report here the isolation and characterization of a Tn5-insertion mutant PXM69. Tn5-insertion mutants were screened on indica rice JG30, which is highly susceptible to PXO99A, by leaf-cutting inoculation.Four mutants with reduced virulence were obtained after two rounds of screening. Among them, the mutant PXM69 had completely lost virulence to the rice host and ability to elicit HR in non-host tobacco. Southern blotting analysis showed a single copy of a Tn5-insertion in the genome of PXM69. PCR walking and sequencing analysis revealed that the Tn5 transposon was inserted at nucleotide position 70,192–70,201 in the genome of PXO99A, disrupting the type III hrc(hrp-conserved) gene hrcQ, the first gene in the D operon of the hrp cluster in Xoo. To confirm the relationship between the Tn5-insertion and the avirulence phenotype of PXM69, we used the marker exchange mutagenesis to create a PXO99Amutant, ΔhrcQ::KAN, in which the hrcQ was disrupted by a kanamycin-encoding gene cassette at the same site as that of the Tn5-insertion. ΔhrcQ::KAN showed the same phenotype as mutant PXM69. Reintroduction of the wild-type hrcQ gene partially complemented the pathogenic function of PXM69. RT-PCR and cellulase secretion assays showed that the Tn5-disruption of hrcQ did not affect transcription of downstream genes in the D operon and function of the type II secretion system. Our results provide new insights into the pathogenic functions of clustered hrp genes in Xoo.展开更多
[Objectives]This study aimed to investigate the pathogenicity,growth characteristics and drug resistance of Streptococcus suis type 2.[Methods]Bacterial isolation and identification,biochemical experiments,determinati...[Objectives]This study aimed to investigate the pathogenicity,growth characteristics and drug resistance of Streptococcus suis type 2.[Methods]Bacterial isolation and identification,biochemical experiments,determination of growth curve and correlation curve between OD 600 values and viable counts,drug susceptibility tests,pathogenicity analysis,and histopathological observations were carried out.[Results]The Streptococcus strain isolated from infected pigs was identified as Streptococcus suis type 2,which was named TA01 strain.TA01 strain reached the growth peak at 6-8 h post-incubation,and viable counts gradually declined after 8 h of incubation.The correlation equation between OD 600 values and viable counts is y=24.659 x-1.076 1,R^2=0.996 7.TA01 strain was sensitive to penicillin,erythromycin,florfenicol and oxacillin,and resistant to ciprofloxacin,polymyxin B and clindamycin.According to the results of pathogenicity analysis,all the mice in 3.6×10^9 cfu/mouse group died within 48,and these dead mice exhibited acute pyaemia septica.Based on the Reed-Muench formula,it was calculated that LD 50 of TA01 strain was 1.137×10^8 cfu/mouse.Pathological examination showed obvious blue-stained bacteria clusters,accompanied by neutrophil infiltration.[Conclusions]TA01 strain was a virulent strain of Streptococcus suis type 2.Compared with Streptococcus strains which were isolated and reported in China,TA01 strain exhibited strong virulence and rapid proliferation.展开更多
The pathogenicity of 4 Chinese strains of subgroup J avian leukosis viruses (ALV-J), SD9901,SD9902, YZ9901 and YZ9902, was studied. The results showed that only SD9902 among the 4 strains induced mortality from myeloi...The pathogenicity of 4 Chinese strains of subgroup J avian leukosis viruses (ALV-J), SD9901,SD9902, YZ9901 and YZ9902, was studied. The results showed that only SD9902 among the 4 strains induced mortality from myeloid leukosis (ML). In the 12 meat-type chickens inoculated with SD9902 at 1-day-old, 9died between 22 days and 38 days after inoculation. No death or ML was found in chickens inoculated with the other 3 strains during the period of 6 months. These results suggested the SD9902 strain of ALV-J was an acute transforming virus, but SD9901, YZ9901 and YZ9902 were non-transforming viruses. All 4 Chinese strains did not induce any tumors in egg-type SPF chickens during 7 months after hatching when viruses were injected into 11-day-old embryos.展开更多
Objective To compare the pathogenicity of isolates of sequence type 7(ST-7)Neisseria meningitidis(N.meningitidis)belonging to four different serogroups(A,B,C,and X).Methods Four ST-7 N.meningitidis isolates serogroupe...Objective To compare the pathogenicity of isolates of sequence type 7(ST-7)Neisseria meningitidis(N.meningitidis)belonging to four different serogroups(A,B,C,and X).Methods Four ST-7 N.meningitidis isolates serogrouped as A,B,C,and X and characterized by different capsule structures,were examined for their adhesion and invasion properties,and their ability to induce cytokine release and apoptosis in the host cell(the A549 cell line).Results Among the four ST-7 N.meningitidis isolates,the serogroup A isolate possessed the strongest adhesion and invasion ability.This isolate also induced the release of the highest levels of the proinflammatory mediators interleukin-6,interleukin-1β,and interferon,and the highest apoptosis rate in the host cells.However,there was no significant difference in interleukin-8 and tumor necrosis factor-αsecretion between the four isolates.Based on the findings,the serogroup X N.meningitidis isolate had the weakest pathogenicity,whereas there was almost no difference in the pathogenicity of the isolates from serogroups B and C.Conclusions The differences in the capsular structure of the four isolates of ST-7 N.meningitidis affected their pathogenic capacities.The findings also imply that the hyperinvasive ST-7 N.meningitidis lineage may include hypoinvasive isolates.展开更多
Autophagy is responsible for maintaining fundamental cellular homeostasis and is,therefore,essential for diverse development processes.This study reported that PoElp3,the putative catalytic subunit of Elongator comple...Autophagy is responsible for maintaining fundamental cellular homeostasis and is,therefore,essential for diverse development processes.This study reported that PoElp3,the putative catalytic subunit of Elongator complex,is involved in the maintenance of autophagy homeostasis to facilitate asexual development and pathogenicity in the rice blast fungus Pyricularia oryzae.It was found that the ΔPoelp3 strains were defective in vegetative growth,conidiation,stress response,and pathogenicity.The mutants exhibited hyper-activated autophagy in the vegetative hyphae under both nutrient-rich and nutrient-deficient conditions.The hyper-activation of autophagy possibly suppressed the production of vegetative hyphae in the ΔPoelp3 strains.Moreover,the ΔPoelp3 strains were found to be more sensitive to rapamycin during vegetative-and invasive-hyphal growth but have no effect on Target-of-Rapamycin(TOR)signaling inhibition.Taken together,these results demonstrated that PoElp3 is involved in asexual development and pathogenicity by regulating autophagy in the rice blast fungus.展开更多
Various virulence-associated genes or pathogenicity island are responsible for determining the pathogenicity of Escherichia coli strains. However, the correlation of the number and combination patterns of virulence-as...Various virulence-associated genes or pathogenicity island are responsible for determining the pathogenicity of Escherichia coli strains. However, the correlation of the number and combination patterns of virulence-associated genes in Escherichia coli strains with their pathogenicity remains largely unknown. In this work, 581 chicken Escherichia coli strains were isolated from 1045 liver samples of dead chickens from 50 chicken farms at four provinces in China during 2007-2012. Based on the pathogenic test of SPF chickens, 320 chickens pathogenic Escherichia coli isolates were identified as highly (n = 193), intermediate (n = 98) and low pathogenic (n = 29) strains, respectively. Furthermore, the number of virulence genes in the 320 chicken pathogenic and 50 non-pathogenic Escherichia coli strains was examined. Our results reveal that thirteen virulence genes in Escherichia coli strains were detected, and all strains carried at least two or more than two virulence-associated genes. This study also suggests that highly pathogenic E. coli strains simultaneously carried at least 8 to13 virulence genes while intermediate pathogenic strains carried at least 5 to 8 virulence genes. The number of virulence-associated genes detected in highly pathogenic strains showed there were more significant differences than that in low pathogenic strains (P irp2, fyuA, and colV in high pathogenic strains was significantly higher than that in low and non-pathogenic strains (P irp2, fyuA, iucA, iucD, iutA, papC, iss, tsh, and colV were more often detected in highly and intermediate pathogenic E. coli strains. Taken together, our results provide evidences demonstrating that the pathogenicity of Escherichia coli strains is closely associated with the number and combination patterns of virulence-associated genes.展开更多
[Objective]This paper was to identify the pathogen of leaf brown-spot on‘gonggan’mandarin(Citrus reticulate var.gonggan)in Zhaoqing,Guangdong Province.[Method]The pathogen was determined based on sequence analysis o...[Objective]This paper was to identify the pathogen of leaf brown-spot on‘gonggan’mandarin(Citrus reticulate var.gonggan)in Zhaoqing,Guangdong Province.[Method]The pathogen was determined based on sequence analysis of ITS,endoPG,tef1,gapdh,Alt a1,rpb2 and opa10-2 genes;the morphological characteristics were recorded on PDA and PCA;and its pathogenicity on excised and intact host leaves of citrus‘gonggan’was tested.[Result]A detailed description of Alternaria gaisen was obtained based on morphological,molecular and pathogenic characterization,which was the causal agent of brown-spot disease on leaves of‘gonggan’mandarin orchard trees in Zhaoqing,Guangdong,China.[Conclusion]This study provides a scientific basis for the effective control of leaf brown-spot on‘gonggan’mandarin.展开更多
Verticillium wilt,caused by the notorious fungal pathogen Verticillium dahliae,is one of the main limiting factors for cotton production.Due to the stable dormant structure microsclerotia,long-term variability and co-...Verticillium wilt,caused by the notorious fungal pathogen Verticillium dahliae,is one of the main limiting factors for cotton production.Due to the stable dormant structure microsclerotia,long-term variability and co-evolution with host plant,its pathogenicity mechanism is very complicated,and the interaction mechanism between pathogen and host plant is also unclear.So identification and functional analysis of the genes involved in the pathogenicity or virulence of this fungus will benefit to uncover the molecular pathogenic mechanism of V.dahliae.In this review,many multifunction genes covering microsclerotia development,pathogen infection,effector proteins,transcription factors,horizontal gene transfer and trans-kingdom RNA silencing have been summarized to provide a theoretical basis to deep understand the molecular pathogenicity mechanism of V.dahliae and promote to effectively control Verticillium wilt.Furtherly,these pathogenicity-related genes may be considered as targets for effective control of Verticillium wilt in cotton.展开更多
Vibrio parahaemolyticus is the main cause of foodborne gastroenteritis,which is widely distributed in shellfish and other seafood.Most V.parahaemolyticus are nonpathogenic,and only a few types,such as serotype O3:K6,a...Vibrio parahaemolyticus is the main cause of foodborne gastroenteritis,which is widely distributed in shellfish and other seafood.Most V.parahaemolyticus are nonpathogenic,and only a few types,such as serotype O3:K6,are pathogenic,which is also the most prevalent strain in Asia.However,the relationship between this serotype and pathogenicity has yet to be established.The waaf gene is located in the O antigen synthesis gene cluster.Thus,we constructed a waaf gene deletion mutant(i.e.,Δwaaf)of wild-type(WT)which isolated from shellfish serotype O3:K6 via chitin-mediated transformation technology.We then constructed theΔwaaf complementary strain(i.e.,C-△waaf)via the Escherichia coli S17λpir strain by conjugation.The basic physiological characteristics,adhesion to Caco2 cells,and pathogenicity of the WT,△waaf,and C-△waaf strains were compared.Growth curves showed no remarkable differences between the WT andΔwaaf strains.However,theΔwaaf strain non-reactive to O3 antisera and other 12 O-group antisera of V.parahaemolyticus.Moreover,the number of flgella and extracellular polysaccharides decreased,the adhesion decreased,and the pathogenicity weakened.These characteristics of the C-△waaf strain were similar to those of the WT strain These results indicated that the waaf gene is vital to the serotype in V.parahaemolyticus,and changes in O antigen could affect the pathogenicity of this bacterium.This study will be helpful to understand the pathogenic mechanism of V.parahaemolyticus.展开更多
基金This research was supported by the National Key Research and Development Program of China(2021YFD1800403)the National Natural Science Foundation of China(32273005 and 32002256).
文摘The serine proteases of Mycobacteria tuberculosis(Mtb)are important contributors to the process of bacterial invasion and its pathogenesis.In the present study,we systematically characterized the role of the Rv1043c protein in Mycobacterium infection by purifying the Rv1043c protein in Escherichia coli and constructing a Mycobacterium smegmatis(Msg)strain overexpressing Rv1043c(Msg_Rv1043c).We found that Rv1043c had serine protease activity and localized to the surface of Mtb.We determined that the optimal pH and temperature for the Rv1043c serine protease were 9.0 and 45°C,respectively.Moreover,the serine protease activity of Rv1043c was enhanced by divalent metal ions of Ca^(2+)and Mg^(2+).Site-directed mutagenesis studies demonstrated that the serine 279 residue in Rv1043c plays a catalytic role.Additionally,mouse model studies confirmed that Rv1043c significantly enhanced the survival of Msg in vivo,induced pulmonary injury and lung cell apoptosis,and promoted the release of pro-inflammatory cytokines interleukin-1βand interleukin-6 in mice.This study presents novel insights into the relationship between mycobacterial serine protease and the pathogenesis of the disease.
基金funded by the National Natural Science Foundation of China(32102143)Shandong Province Natural Sciences Foundation of China(ZR2019PC011 and ZR2020QC122)+1 种基金Scientific Research Foundation for Ph.D.Programs of Zaozhuang University(2018BS040 and 2018BS042)Science and Technology Program of Zaozhuang(2019NS03).
文摘Infection of plum bark necrosis stem pitting associated virus(PBNSPaV)has been reported in many Prunus species in several countries,causing significant economic losses.The very small proteins encoded by plant viruses are often overlooked due to their short sequences and uncertain significance.However,numerous studies have indicated that they might play important roles in the pathogenesis of virus infection.The role of small hydrophobic protein P6,encoded by the open reading frame 2 of PBNSPaV,has not been well explored.In this study,we amplified the P6 fragment from a PBNSPaV isolate by RT-PCR using specific primers and found that it is 174 bp long and encodes a protein of approximately 6.3 kD with a transmembrane domain.Subcellular localization analysis of P6 proteins in tobacco leaves showed that P6 localizes to the cytomembrane and nuclear membrane.To further clarify the pathogenicity of P6 proteins,we constructed a PVX-P6 expression vector by inserting the p6 fragment into a potato virus X(PVX)-based vector and transformed it into Agrobacterium tumefaciens GV3101.Infiltration of Nicotiana benthamiana(N.benthamiana)with the PVX vector-transformed A.tumefaciens led to slight mosaic symptoms at 14 days of post-inoculation.Meanwhile,infiltration with the PVX-P6 vector-transformed A.tumefaciens resulted in no significant symptoms.These results demonstrated that heterologous expression of P6 in N.benthamiana could not enhance the pathogenicity of PVX.Our study indicates that P6 may not be a potential pathogenic factor associate with the causing of symptoms,and the mode of action of PBNSPaV-P6 protein remains to be further studied.
基金financially supported by China Agriculture Research System of MOF and MARA(CARS-14)the Key Project of Science and Technology of Henan province(201300110600)+4 种基金Zhongyuan Science and Technology Innovation Leading Talent Plan(214200510020)the Zhongyuan Scientist Workshop Construction(214400510026)the Science and Technology Research Project of Henan Province(222102110081)Key Research and Development Project of Henan Province(22111520400)Distinguished Young Scholars from Henan Academy of Agricultural Sciences(2022JQ01).
文摘Fusarium wilt is a common fungal disease in sesame caused by Fusarium oxysporum f.sp.sesami(FOS).To determine the toxin production profiles of the FOS isolates with different pathogenicity levels under various culture conditions,we assessed the content variation of fusaric acid(FA)and 9,10-dehydrofusaric acid(9,10-DFA)produced by the four representative FOS isolates.Results indicated that the concentration of FA reached to a maximum of 2848.66μg/mL in Czapek medium,while 9,10-DFA was mainly produced in Richard and Lowcarbon Richard medium.The concentration of 9,10-DFA on Richard culture medium varied from 0μg/mL to 716.89μg/mL.Of the five culture media used in this study,Czapek culture medium was the most conductive to produce FA.FA production was significantly affected by culture medium,culture time,and their interactions.Results suggest that there is no correlation between toxin production and pathogenicity level of FOS isolates.These findings provide key information for the mechanism analysis of FOS-sesame interaction and pathogen control.
基金Supported by High level Talents Project of Hainan Provincial Natural Science Foundation of China(2019RC278)The Earmarked Fund for CARS(CARS-31)。
文摘[Objectives]The paper was to study molecular characterization,morphology and pathogenicity of Curvularia pseudobrachyspora,a new causal agent of leaf spot on banana.[Methods]Banana(Musa acuminate)leaves with streaks or long ellipse-shaped lesions were sampled in an orchard of Danzhou City,Hainan Province,China in 2021.Fungus isolates were isolated from the diseased tissues and further identified as C.pseudobrachyspora based on morphological characteristics of colony,conidiophore and spore,phylogenetic analyses of the ITS region,GAPDH and TEF-1αgenes.[Results]In the pathogenicity test,the fungus re-isolated from inoculated leaves with necrotic lesions was identified morphologically and molecularly,fulfilling Koch's postulates.[Conclusions]C.pseudobrachyspora is a new pathogen causing leaf spot of banana in China and the world.
文摘Peanut (Arachis hypogaea L.) late leaf spot is an important disease caused by Phaeoisariopsis personata (Berk. Et M. A Curt.). This fungus is responsible for the most damaging leaf spots in peanut production. The present experiment was undertaken to evaluate the pathogenic variability of Phaeoisariopsis personata in Burkina Faso. To this end, detached leaves and healthy plants of three peanut varieties were inoculated. Isolates I3TF, I2TG and I1TK of the pathogen (10<sup>5</sup> conidia/ml), collected respectively in the western, central and eastern agroecological zones of country, were used. The inoculated leaves were kept in Petri dishes on moist blotting paper and stored in the laboratory during the experimental period. The inoculated plants were grown under glass in pots containing a mixture of sterilized sand and clay. The development of disease was monitored and severity was scored every 15 days using rating scale. The results obtained in the laboratory and in the greenhouse revealed that there is pathogenic variability in the isolates tested. Indeed, for each variety, the highest severity score was recorded in plants inoculated with isolate I3TF and the lowest severity score with isolate I1TG. In the laboratory the severity scores ranged from 6.76 to 8.80 in TS32-1, 6.18 to 8.29 in SH70P and 5.98 to 7.92 in PC79-79. In the greenhouse, the average severity scores ranged from 5.61 to 8.33 in TS32-1, from 5.19 to 8.00 in SH70P, from 4.90 to 7.50 in PC79-79. Thus, the variety TS32-1 was the most susceptible to all three isolates of the pathogen.
文摘Biological nature of the bacterial pathogenicity phenomenon is based on the interaction of prokaryotic and eukaryotic organisms. The phenomenon is the poly-functional biological potency of germs that are realized by factors (determinants) of pathogenicity. Some fundamental biological functions are responsible for bacterial pathogenicity in a multi-cellular host organism: the adhesive function, the function of invasion and penetration into the cell, the function of evasion of host defense, and the damage function. The action of adhesion, invasion and evasionis directed to towards establishing an ecological niche in multi-cellular host while the aim of the damaging function is destruction of the environment.
基金Supported by the Natural Science Foundation of Fujian Province,China,No.95A003
文摘AIM To explore the virulence and the potential pathogenicity of coccoid Helicobacter pylori (H. pylori) transformed from spiral form by exposure to antibiotic.METHODS Three strains of H. pylori, isolated from gastric biopsy specimens of confirmed peptic ulcer, were converted from spiral into coccoid from by exposure to metronidazole.Both spiral and coccoid form of H. pylori were tested for the urease activity, the adherence to Hep-2 cells and the vacuolating cytotoxicity to Hela cells, and the differences of the protein were analysed by SDS-PAGE and Western blot,The mutation of the genes including ureA, ureB,hpaA; vacA and cagA, related with virulence,was detected by means of PCR and PCR-SSCP.RESULTS In the coccoid H. pylori, the urease activity, the adherence to Hep-2 cells and the vacuolating cytotoxicity to Hela cells alldecreased. In strain F44, the rate and index of adherence reduced from 70.0% ± 5.3% to 33% ±5.1% and from 2.6 ±0.4 to 0.96 ±0.3 (P＜0.01),respectively. The invasion of coccoid H. pylori into Hep-2 cell could be seen under electronmicroscope. SDS-PAGE showed that the content of the protein with the molecular weight over Mr74 000 decreased, and the hybriditional signal in band Mr 125 000 weakened, while the band Mr 110000 and Mr63000 strengthened in coccoid H. pylori as shown in Western blot. The results of PCR were all positive, and PCR-SSCP indicated that there may exist the point mutation in gene hpaA or vacA.CONCLUSION The virulence and the proteins with molecular weight over Mr74 000 in coccoid H. pylori decrease, but no deletion exists in amplification fragments from ureA, ureB, hpaA,vacA and cagA genes, suggesting that coccoid H. pylori may have potential pathogenicity.
基金supported by the National Basic Research Program of China (2013CB127700)National Natural ScienceFoundation of China (31371882, 31401693)the 111 Project of the Ministry of Education of China (B07049)
文摘Obligate biotrophic fungi cause serious and widespread diseases of crop plants, but are challenging to investigate because they cannot be cultured in vitro. The two economically important groups of biotrophic fungi parasitizing wheat are the rust and powdery mildew pathogens, but their obligate biotrophic lifestyles and pathogenicity mechanisms are not well understood at the molecular level. With the advent of next generation sequencing technology, increasing numbers of pathogen genomes are becoming available. Research in plant pathology has entered a new genomics era. This review summarizes recent progress in understanding the biology and pathogenesis of biotrophic fungal pathogens attacking wheat based on pathogen genomics. We particularly focus on the three wheat rust and the powdery mildew fungi in regard to genome sequencing, avirulence gene cloning, effector discovery, and pathogenomics. We predict that coordinated study of both wheat and its pathogens should reveal new insights in biotrophic adaptation, pathogenicity mechanisms,and population dynamics of these fungi that will assist in development of new strategies for breeding wheat varieties with durable resistance.
基金the Science Foundation of Jiangsu Province,No.BK97173
文摘AIM To study the pathogenicity of hepatitis G virus (HGV) and observe the genesis and pathological process of hepatitis G.METHODS HGV-RNA in serum was detected by RT-PCR assay. The immunohistochemical assays of liver tissue were performed with HGV monocoloned antibody (McAb)expressed from the region of HGV NS5 nucleic acid sequence. The clinical and pathological data of 52 patients with hepatitis G were discussed. In animal experiment,the Chinese Rhesus monkeys were infected with the serum of a patient with HGV infection. And the dynamic changes in serology and liver histology of animals were observed.RESULTS One hundred and fifty-four patients with HGVRNA positive were selected from 1552 patients with various kinds of hepatitis. Of 154 patients with HGV infection, 52 were infected with HGV only, which accounted for 33.8% (52/154) and 102 with positive HGVRNA were super-infected with other hepatitis viruses,which accounted for 66.2% (102/154). The clinical and pathological observation showed that the acute and chronic hepatitis could be induced by HGV. The slight abnormality of transaminases ALT and AST in serum of monkeys lasted nearly 12 months and histological results showed a series of pathological changes.CONCLUSION HGV is a hepatotropic virus and has pathogenicty.
基金Supported by Major Science and Technology Program in Henan Province,No.131100110200
文摘AIM:To test the pathogenicity of pseudorabies virus(PRV)variant HN1201 and compare its pathogenicity with a classical PRV Fa strain.METHODS:The pathogenicity of the newly-emerging PRV variant HN1201 was evaluated by different inoculating routes,virus loads,and ages of pigs.The classical PRV Fa strain was then used to compare with HN1201 to determine pathogenicity.Clinical symptoms after virus infection were recorded daily and average daily body weight was used to measure the growth performance of pigs.At necropsy,gross pathology and histopathology were used to evaluate the severity of tissue damage caused by virus infection.RESULTS:The results showed that the efficient infection method of RPV HN1201 was via intranasal inoculation at 107 TCID50,and that the virus has high pathogenicity to 35-to 127-d old pigs.Compared with Fa strain,pigs infected with HN1201 showed more severe clinical symptoms and pathological lesions.Immunochemistry results revealed HN1201 had more abundant antigen distribution in extensive organs.CONCLUSION:All of the above results suggest that PRV variant HN1201 was more pathogenic to pigs than the classical Fa strain.
基金supported by the National Natural Science Foundation of China (No. 31171812)
文摘Bacterial blight, caused by Xanthomonas oryzae pv. oryzae(Xoo), is one of the most destructive diseases of rice(Oryza sativa L.) worldwide. The type III secretion system(T3SS) of Xoo, encoded by the hrp(hypersensitive response and pathogenicity) genes, plays critical roles in conferring pathogenicity in host rice and triggering a hypersensitive response(HR) in non-host plants. To investigate the major genes conferring the pathogenicity and avirulence of Xoo, we previously constructed a random Tn5-insertion mutant library of Xoo strain PXO99A. We report here the isolation and characterization of a Tn5-insertion mutant PXM69. Tn5-insertion mutants were screened on indica rice JG30, which is highly susceptible to PXO99A, by leaf-cutting inoculation.Four mutants with reduced virulence were obtained after two rounds of screening. Among them, the mutant PXM69 had completely lost virulence to the rice host and ability to elicit HR in non-host tobacco. Southern blotting analysis showed a single copy of a Tn5-insertion in the genome of PXM69. PCR walking and sequencing analysis revealed that the Tn5 transposon was inserted at nucleotide position 70,192–70,201 in the genome of PXO99A, disrupting the type III hrc(hrp-conserved) gene hrcQ, the first gene in the D operon of the hrp cluster in Xoo. To confirm the relationship between the Tn5-insertion and the avirulence phenotype of PXM69, we used the marker exchange mutagenesis to create a PXO99Amutant, ΔhrcQ::KAN, in which the hrcQ was disrupted by a kanamycin-encoding gene cassette at the same site as that of the Tn5-insertion. ΔhrcQ::KAN showed the same phenotype as mutant PXM69. Reintroduction of the wild-type hrcQ gene partially complemented the pathogenic function of PXM69. RT-PCR and cellulase secretion assays showed that the Tn5-disruption of hrcQ did not affect transcription of downstream genes in the D operon and function of the type II secretion system. Our results provide new insights into the pathogenic functions of clustered hrp genes in Xoo.
基金Supported by National Key Basic Research Program of China(973 Program)(2017YFD0500605)
文摘[Objectives]This study aimed to investigate the pathogenicity,growth characteristics and drug resistance of Streptococcus suis type 2.[Methods]Bacterial isolation and identification,biochemical experiments,determination of growth curve and correlation curve between OD 600 values and viable counts,drug susceptibility tests,pathogenicity analysis,and histopathological observations were carried out.[Results]The Streptococcus strain isolated from infected pigs was identified as Streptococcus suis type 2,which was named TA01 strain.TA01 strain reached the growth peak at 6-8 h post-incubation,and viable counts gradually declined after 8 h of incubation.The correlation equation between OD 600 values and viable counts is y=24.659 x-1.076 1,R^2=0.996 7.TA01 strain was sensitive to penicillin,erythromycin,florfenicol and oxacillin,and resistant to ciprofloxacin,polymyxin B and clindamycin.According to the results of pathogenicity analysis,all the mice in 3.6×10^9 cfu/mouse group died within 48,and these dead mice exhibited acute pyaemia septica.Based on the Reed-Muench formula,it was calculated that LD 50 of TA01 strain was 1.137×10^8 cfu/mouse.Pathological examination showed obvious blue-stained bacteria clusters,accompanied by neutrophil infiltration.[Conclusions]TA01 strain was a virulent strain of Streptococcus suis type 2.Compared with Streptococcus strains which were isolated and reported in China,TA01 strain exhibited strong virulence and rapid proliferation.
基金supported by the National Natural Science Eoundation of China(30040011)
文摘The pathogenicity of 4 Chinese strains of subgroup J avian leukosis viruses (ALV-J), SD9901,SD9902, YZ9901 and YZ9902, was studied. The results showed that only SD9902 among the 4 strains induced mortality from myeloid leukosis (ML). In the 12 meat-type chickens inoculated with SD9902 at 1-day-old, 9died between 22 days and 38 days after inoculation. No death or ML was found in chickens inoculated with the other 3 strains during the period of 6 months. These results suggested the SD9902 strain of ALV-J was an acute transforming virus, but SD9901, YZ9901 and YZ9902 were non-transforming viruses. All 4 Chinese strains did not induce any tumors in egg-type SPF chickens during 7 months after hatching when viruses were injected into 11-day-old embryos.
基金supported by the grants from the National Key Program for Infectious Disease of China[No.2018ZX10101002-001-014]the National Natural Scientific Foundation[No.81602903]+1 种基金the Ministry of Science and Technology of the People’s Republic of Chinathe Sanming Project of Medicine in Shenzhen[No.SZSM201803081].
文摘Objective To compare the pathogenicity of isolates of sequence type 7(ST-7)Neisseria meningitidis(N.meningitidis)belonging to four different serogroups(A,B,C,and X).Methods Four ST-7 N.meningitidis isolates serogrouped as A,B,C,and X and characterized by different capsule structures,were examined for their adhesion and invasion properties,and their ability to induce cytokine release and apoptosis in the host cell(the A549 cell line).Results Among the four ST-7 N.meningitidis isolates,the serogroup A isolate possessed the strongest adhesion and invasion ability.This isolate also induced the release of the highest levels of the proinflammatory mediators interleukin-6,interleukin-1β,and interferon,and the highest apoptosis rate in the host cells.However,there was no significant difference in interleukin-8 and tumor necrosis factor-αsecretion between the four isolates.Based on the findings,the serogroup X N.meningitidis isolate had the weakest pathogenicity,whereas there was almost no difference in the pathogenicity of the isolates from serogroups B and C.Conclusions The differences in the capsular structure of the four isolates of ST-7 N.meningitidis affected their pathogenic capacities.The findings also imply that the hyperinvasive ST-7 N.meningitidis lineage may include hypoinvasive isolates.
基金supported by grants from the National Natural Science Foundation of China(31770156 and 2016YFD0300700)the Innovative Research Funding of FAFU,China(CXZX2018051 and CXZX2018052)。
文摘Autophagy is responsible for maintaining fundamental cellular homeostasis and is,therefore,essential for diverse development processes.This study reported that PoElp3,the putative catalytic subunit of Elongator complex,is involved in the maintenance of autophagy homeostasis to facilitate asexual development and pathogenicity in the rice blast fungus Pyricularia oryzae.It was found that the ΔPoelp3 strains were defective in vegetative growth,conidiation,stress response,and pathogenicity.The mutants exhibited hyper-activated autophagy in the vegetative hyphae under both nutrient-rich and nutrient-deficient conditions.The hyper-activation of autophagy possibly suppressed the production of vegetative hyphae in the ΔPoelp3 strains.Moreover,the ΔPoelp3 strains were found to be more sensitive to rapamycin during vegetative-and invasive-hyphal growth but have no effect on Target-of-Rapamycin(TOR)signaling inhibition.Taken together,these results demonstrated that PoElp3 is involved in asexual development and pathogenicity by regulating autophagy in the rice blast fungus.
文摘Various virulence-associated genes or pathogenicity island are responsible for determining the pathogenicity of Escherichia coli strains. However, the correlation of the number and combination patterns of virulence-associated genes in Escherichia coli strains with their pathogenicity remains largely unknown. In this work, 581 chicken Escherichia coli strains were isolated from 1045 liver samples of dead chickens from 50 chicken farms at four provinces in China during 2007-2012. Based on the pathogenic test of SPF chickens, 320 chickens pathogenic Escherichia coli isolates were identified as highly (n = 193), intermediate (n = 98) and low pathogenic (n = 29) strains, respectively. Furthermore, the number of virulence genes in the 320 chicken pathogenic and 50 non-pathogenic Escherichia coli strains was examined. Our results reveal that thirteen virulence genes in Escherichia coli strains were detected, and all strains carried at least two or more than two virulence-associated genes. This study also suggests that highly pathogenic E. coli strains simultaneously carried at least 8 to13 virulence genes while intermediate pathogenic strains carried at least 5 to 8 virulence genes. The number of virulence-associated genes detected in highly pathogenic strains showed there were more significant differences than that in low pathogenic strains (P irp2, fyuA, and colV in high pathogenic strains was significantly higher than that in low and non-pathogenic strains (P irp2, fyuA, iucA, iucD, iutA, papC, iss, tsh, and colV were more often detected in highly and intermediate pathogenic E. coli strains. Taken together, our results provide evidences demonstrating that the pathogenicity of Escherichia coli strains is closely associated with the number and combination patterns of virulence-associated genes.
基金Guangxi Key Laboratory of Biology for Crop Disease and Insect Pests(2019-KF-01).
文摘[Objective]This paper was to identify the pathogen of leaf brown-spot on‘gonggan’mandarin(Citrus reticulate var.gonggan)in Zhaoqing,Guangdong Province.[Method]The pathogen was determined based on sequence analysis of ITS,endoPG,tef1,gapdh,Alt a1,rpb2 and opa10-2 genes;the morphological characteristics were recorded on PDA and PCA;and its pathogenicity on excised and intact host leaves of citrus‘gonggan’was tested.[Result]A detailed description of Alternaria gaisen was obtained based on morphological,molecular and pathogenic characterization,which was the causal agent of brown-spot disease on leaves of‘gonggan’mandarin orchard trees in Zhaoqing,Guangdong,China.[Conclusion]This study provides a scientific basis for the effective control of leaf brown-spot on‘gonggan’mandarin.
基金supported by the Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural SciencesCentral Publicinterest Scientific Institution Basal Research Fund (No. 1610162021031).
文摘Verticillium wilt,caused by the notorious fungal pathogen Verticillium dahliae,is one of the main limiting factors for cotton production.Due to the stable dormant structure microsclerotia,long-term variability and co-evolution with host plant,its pathogenicity mechanism is very complicated,and the interaction mechanism between pathogen and host plant is also unclear.So identification and functional analysis of the genes involved in the pathogenicity or virulence of this fungus will benefit to uncover the molecular pathogenic mechanism of V.dahliae.In this review,many multifunction genes covering microsclerotia development,pathogen infection,effector proteins,transcription factors,horizontal gene transfer and trans-kingdom RNA silencing have been summarized to provide a theoretical basis to deep understand the molecular pathogenicity mechanism of V.dahliae and promote to effectively control Verticillium wilt.Furtherly,these pathogenicity-related genes may be considered as targets for effective control of Verticillium wilt in cotton.
基金supported by grants from the Natural Science Foundation of Chongqing(cstc2020jcyj-msxm X0685)the Science and Technology Research Program of Chongqing Municipal Education Commission(KJQN202001231)+1 种基金the National Natural Science Foundation of China(NSFC)(No.31201372)Science and Technology Project of Wanzhou in 2020。
文摘Vibrio parahaemolyticus is the main cause of foodborne gastroenteritis,which is widely distributed in shellfish and other seafood.Most V.parahaemolyticus are nonpathogenic,and only a few types,such as serotype O3:K6,are pathogenic,which is also the most prevalent strain in Asia.However,the relationship between this serotype and pathogenicity has yet to be established.The waaf gene is located in the O antigen synthesis gene cluster.Thus,we constructed a waaf gene deletion mutant(i.e.,Δwaaf)of wild-type(WT)which isolated from shellfish serotype O3:K6 via chitin-mediated transformation technology.We then constructed theΔwaaf complementary strain(i.e.,C-△waaf)via the Escherichia coli S17λpir strain by conjugation.The basic physiological characteristics,adhesion to Caco2 cells,and pathogenicity of the WT,△waaf,and C-△waaf strains were compared.Growth curves showed no remarkable differences between the WT andΔwaaf strains.However,theΔwaaf strain non-reactive to O3 antisera and other 12 O-group antisera of V.parahaemolyticus.Moreover,the number of flgella and extracellular polysaccharides decreased,the adhesion decreased,and the pathogenicity weakened.These characteristics of the C-△waaf strain were similar to those of the WT strain These results indicated that the waaf gene is vital to the serotype in V.parahaemolyticus,and changes in O antigen could affect the pathogenicity of this bacterium.This study will be helpful to understand the pathogenic mechanism of V.parahaemolyticus.
