Nursery plant propagation by grafting has been widely used in modern viticulture to minimize the damage caused by biotic and abiotic stresses.In grapevine(Vitis spp.),an effective way to control disease damage is to p...Nursery plant propagation by grafting has been widely used in modern viticulture to minimize the damage caused by biotic and abiotic stresses.In grapevine(Vitis spp.),an effective way to control disease damage is to provide producers and growers with pathogen-free stock plants.In this study,five grapevine rootstock varieties,‘SO4’,‘101-14’,‘5BB’,‘110R’and‘1103P’,were selected as explants to establish an in vitro culture protocol,and three species of grapevine viruses were tested by real-time RT-PCR.The results showed that MS medium supplemented with 0.2 mg/L IBA,1.0 mg/L 6-BA,0.5 mg/L KT,4.0 mg/L adenine for culture initiation,and WPM supplemented with 0.2 mg/L IBA for subculture were suitable for all five rootstock varieties,with multiplication coefficients ranging from 1.6 to 4.4.Virus testing showed that single RT-PCR was more effective for detecting the three viruses compared to double or triple RT-PCR.Only plantlets free from the aforementioned viruses were retained for subculture.Plantlets were hardened at room temperature under natural lighting in Hoagland solution for 2 weeks and transplanted to pots filled with mixed media in a greenhouse.This protocol is applicable for rapid propagation of the five grapevine rootstock varieties and can be used for commercial production of virus-free grapevine stocks.展开更多
The effect of maternal antibodies on the pathogenesis of avian reovirus （ARV） was studied in commercial and specific pathogen free broilers （SPF） using a real-time reverse transcriptase （RT）-polymerase chain rea...The effect of maternal antibodies on the pathogenesis of avian reovirus （ARV） was studied in commercial and specific pathogen free broilers （SPF） using a real-time reverse transcriptase （RT）-polymerase chain reaction （PCR） assay, along with the incidence and severity of morbidity, mortality, and gross lesions. ARV RNA was detected in cloacal swabs in both bird groups from the first day throughout the 21 days experiment. Commercial broiler chickens, which had high maternal antibodies against ARV, showed minimum clinical signs, gross lesions, and lower numbers of birds with viral RNA excretion, whereas specific pathogen free （SPF） broiler chickens, which did not have antibody against ARVs, had 30% mortality, more severe signs, and higher numbers of birds excreting viral RNA. The highest peak of SPF birds excreting viral RNA occurred during the time of maximum mortality. The protective effect of maternal antibody on ARV pathogenesis in broiler chickens correlated with the detection of ARV RNA using the real-time RT-PCR.展开更多
Dicistroviruses comprise a newly characterized and rapidly expanding family of small RNA viruses of invertebrates. Several features of this virus group have attracted considerable research interest in recent years. In...Dicistroviruses comprise a newly characterized and rapidly expanding family of small RNA viruses of invertebrates. Several features of this virus group have attracted considerable research interest in recent years. In this review I provide an overview of the Dicistroviridae and describe progress made toward the understanding and practical application of dicistroviruses, including (i) construction of the first infectious clone of a dicistrovirus, (ii) use of the baculovirus expression system for production of an infectious dicistrovirus, (iii) the use of Drosophila C virus for analysis of host response to virus infection, and (iv) correlation of the presence of Israeli acute paralysis virus with honey bee colony collapse disorder. The potential use of dicistroviruses for insect pest management is also discussed. The structure, mechanism and practical use of the internal ribosome entry site (IRES) elements has recently been reviewed elsewhere.展开更多
Influenza type A, is an avian disease with a complicated ecology and transmission routes in verity of avian and mammalian species. The present study aimed to demonstrate the characteristic, clinical and experimental f...Influenza type A, is an avian disease with a complicated ecology and transmission routes in verity of avian and mammalian species. The present study aimed to demonstrate the characteristic, clinical and experimental features as well as pathogenecity of Avian Influenza Virus H5N2 through a laboratory-based experiment in western Iran. A post-mortem examination of experimentally chickens was undertaken in 2007. Overall 25 local native chickens including 15 layers and 10 roosters suspected with AI infection as well as 50 experimental chickens were studied. The virus was isolated from the embryonated specific pathogen-free （SPF） chicken eggs. There was an embryo mortality rate of 71% within 48 hours post inoculation （PI）. Hemagglutinin （HA） inhibition titres against AIV subtype H5N2 in the layers ranged from 4.20 to 4.75 （acute） and 6.21 to 7.82 （convalescent）. Accumulated mucous in trachea of the dissected birds, congested lungs, atrophied bursa, haemorrhagic cecal tonsils and inflamed thymus were the main clinical symptoms. Thickened and infected air sacs, pre hepatitis and enteritis signs were also observed, in experimental birds, the eyes＇ colour became red and the eyelashes were almost double in diameters after being infected. The AI virus found in the present study was classified as a highly pathogenic avian influenza.展开更多
Objective To detect the virus in the feces and sera of patients in an outbreak of enterically transmitted non-A,non-E hepatitis,and this review covers the epidemiologic features and experimental infection of this nove...Objective To detect the virus in the feces and sera of patients in an outbreak of enterically transmitted non-A,non-E hepatitis,and this review covers the epidemiologic features and experimental infection of this novel virus.Data sources Data sources come from our own work on this subject,published and unpublished.Study selection Mainly our own work is included,and related literature is collected.Results In an outbreak of enterically transmitted non-A-E hepatitis among students,a total of 381 cases (60.7%)were documented.Viral fragments identical to transfusion transmitted virus(TTV)were detected in both serum and stool samples.Asymptomatic virus carriers among the staff had positive serum(32.1%)and feces(24.6%),clearly a potential source of infection.This viral infection prevalence in 2 remote villages in northern and southern China was 9.2% and 10.6%,respectively,suggesting that China is an endemic area.In this study,groups of 3 Rhesus monkeys were infected via oral or intravenous inoculation with patient feces.Two additional monkeys were infected by passage.The virus was detected in serum,peripheral blood mononuclear cell(PBMC),liver,spleen and small intestine,while the virus positive single strand,which might be a replicative intermediate,was only in liver,intestine and PBMC of all animals.Conclusions This nonenveloped DNA virus might be transmitted both by blood and enteric routes.Considering its wide distribution and high prevalence,we suppose that nonparenteral transmission is more important.展开更多
Gene silencing (RNA silencing) plays a fundamental role in antiviral defense in plants, fungi and invertebrates. Viruses encode proteins that suppress gene silencing to counter host defense. Viral suppressors of RNA s...Gene silencing (RNA silencing) plays a fundamental role in antiviral defense in plants, fungi and invertebrates. Viruses encode proteins that suppress gene silencing to counter host defense. Viral suppressors of RNA silencing (VSRs) have been identified from almost all plant virus genera and some viruses of insects and mammals. Recent studies have revealed that VSRs counter host defense and interfere with host gene regulation by interacting with RNA or important components of the RNA silencing pathway. Here, we review the current understanding of the complex mechanisms of VSRs that have been revealed by recent studies.展开更多
Age and infection age have significant influence on the transmission of infectious dis- eases, such as HIV/AIDS and TB. A discrete SEIT model with age and infection age structures is formulated to investigate the dyna...Age and infection age have significant influence on the transmission of infectious dis- eases, such as HIV/AIDS and TB. A discrete SEIT model with age and infection age structures is formulated to investigate the dynamics of the disease spread. The basic reproduction number R0 is defined and used as the threshold parameter to character- ize the disease extinction or persistence. It is shown that the disease-free equilibrium is globally stable if R0 〈 1, and it is unstable if R0 〉 1. When R0 〉 1, there exists an endemic equilibrium, and the disease is uniformly persistent. The stability of the endemic equilibrium is investigated numerically.展开更多
文摘Nursery plant propagation by grafting has been widely used in modern viticulture to minimize the damage caused by biotic and abiotic stresses.In grapevine(Vitis spp.),an effective way to control disease damage is to provide producers and growers with pathogen-free stock plants.In this study,five grapevine rootstock varieties,‘SO4’,‘101-14’,‘5BB’,‘110R’and‘1103P’,were selected as explants to establish an in vitro culture protocol,and three species of grapevine viruses were tested by real-time RT-PCR.The results showed that MS medium supplemented with 0.2 mg/L IBA,1.0 mg/L 6-BA,0.5 mg/L KT,4.0 mg/L adenine for culture initiation,and WPM supplemented with 0.2 mg/L IBA for subculture were suitable for all five rootstock varieties,with multiplication coefficients ranging from 1.6 to 4.4.Virus testing showed that single RT-PCR was more effective for detecting the three viruses compared to double or triple RT-PCR.Only plantlets free from the aforementioned viruses were retained for subculture.Plantlets were hardened at room temperature under natural lighting in Hoagland solution for 2 weeks and transplanted to pots filled with mixed media in a greenhouse.This protocol is applicable for rapid propagation of the five grapevine rootstock varieties and can be used for commercial production of virus-free grapevine stocks.
文摘The effect of maternal antibodies on the pathogenesis of avian reovirus （ARV） was studied in commercial and specific pathogen free broilers （SPF） using a real-time reverse transcriptase （RT）-polymerase chain reaction （PCR） assay, along with the incidence and severity of morbidity, mortality, and gross lesions. ARV RNA was detected in cloacal swabs in both bird groups from the first day throughout the 21 days experiment. Commercial broiler chickens, which had high maternal antibodies against ARV, showed minimum clinical signs, gross lesions, and lower numbers of birds with viral RNA excretion, whereas specific pathogen free （SPF） broiler chickens, which did not have antibody against ARVs, had 30% mortality, more severe signs, and higher numbers of birds excreting viral RNA. The highest peak of SPF birds excreting viral RNA occurred during the time of maximum mortality. The protective effect of maternal antibody on ARV pathogenesis in broiler chickens correlated with the detection of ARV RNA using the real-time RT-PCR.
基金This journal paper of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa,Project No. 6673, was supported by the Iowa State University Plant Sciences Institute, and the Consortium for Plant Biotechnology Research
文摘Dicistroviruses comprise a newly characterized and rapidly expanding family of small RNA viruses of invertebrates. Several features of this virus group have attracted considerable research interest in recent years. In this review I provide an overview of the Dicistroviridae and describe progress made toward the understanding and practical application of dicistroviruses, including (i) construction of the first infectious clone of a dicistrovirus, (ii) use of the baculovirus expression system for production of an infectious dicistrovirus, (iii) the use of Drosophila C virus for analysis of host response to virus infection, and (iv) correlation of the presence of Israeli acute paralysis virus with honey bee colony collapse disorder. The potential use of dicistroviruses for insect pest management is also discussed. The structure, mechanism and practical use of the internal ribosome entry site (IRES) elements has recently been reviewed elsewhere.
文摘Influenza type A, is an avian disease with a complicated ecology and transmission routes in verity of avian and mammalian species. The present study aimed to demonstrate the characteristic, clinical and experimental features as well as pathogenecity of Avian Influenza Virus H5N2 through a laboratory-based experiment in western Iran. A post-mortem examination of experimentally chickens was undertaken in 2007. Overall 25 local native chickens including 15 layers and 10 roosters suspected with AI infection as well as 50 experimental chickens were studied. The virus was isolated from the embryonated specific pathogen-free （SPF） chicken eggs. There was an embryo mortality rate of 71% within 48 hours post inoculation （PI）. Hemagglutinin （HA） inhibition titres against AIV subtype H5N2 in the layers ranged from 4.20 to 4.75 （acute） and 6.21 to 7.82 （convalescent）. Accumulated mucous in trachea of the dissected birds, congested lungs, atrophied bursa, haemorrhagic cecal tonsils and inflamed thymus were the main clinical symptoms. Thickened and infected air sacs, pre hepatitis and enteritis signs were also observed, in experimental birds, the eyes＇ colour became red and the eyelashes were almost double in diameters after being infected. The AI virus found in the present study was classified as a highly pathogenic avian influenza.
文摘Objective To detect the virus in the feces and sera of patients in an outbreak of enterically transmitted non-A,non-E hepatitis,and this review covers the epidemiologic features and experimental infection of this novel virus.Data sources Data sources come from our own work on this subject,published and unpublished.Study selection Mainly our own work is included,and related literature is collected.Results In an outbreak of enterically transmitted non-A-E hepatitis among students,a total of 381 cases (60.7%)were documented.Viral fragments identical to transfusion transmitted virus(TTV)were detected in both serum and stool samples.Asymptomatic virus carriers among the staff had positive serum(32.1%)and feces(24.6%),clearly a potential source of infection.This viral infection prevalence in 2 remote villages in northern and southern China was 9.2% and 10.6%,respectively,suggesting that China is an endemic area.In this study,groups of 3 Rhesus monkeys were infected via oral or intravenous inoculation with patient feces.Two additional monkeys were infected by passage.The virus was detected in serum,peripheral blood mononuclear cell(PBMC),liver,spleen and small intestine,while the virus positive single strand,which might be a replicative intermediate,was only in liver,intestine and PBMC of all animals.Conclusions This nonenveloped DNA virus might be transmitted both by blood and enteric routes.Considering its wide distribution and high prevalence,we suppose that nonparenteral transmission is more important.
基金supported by the National Basic Research Program of China (Grant No. 2012CB114004)the National Natural Science Foundation of China (Grant Nos. 31030005 and 30910103904)
文摘Gene silencing (RNA silencing) plays a fundamental role in antiviral defense in plants, fungi and invertebrates. Viruses encode proteins that suppress gene silencing to counter host defense. Viral suppressors of RNA silencing (VSRs) have been identified from almost all plant virus genera and some viruses of insects and mammals. Recent studies have revealed that VSRs counter host defense and interfere with host gene regulation by interacting with RNA or important components of the RNA silencing pathway. Here, we review the current understanding of the complex mechanisms of VSRs that have been revealed by recent studies.
文摘Age and infection age have significant influence on the transmission of infectious dis- eases, such as HIV/AIDS and TB. A discrete SEIT model with age and infection age structures is formulated to investigate the dynamics of the disease spread. The basic reproduction number R0 is defined and used as the threshold parameter to character- ize the disease extinction or persistence. It is shown that the disease-free equilibrium is globally stable if R0 〈 1, and it is unstable if R0 〉 1. When R0 〉 1, there exists an endemic equilibrium, and the disease is uniformly persistent. The stability of the endemic equilibrium is investigated numerically.
