Duck hepatitis B virus(DHBV) shares many basic characteristics with hepatitis B virus(HBV) and is an attractive model for vaccine development. In this study, DHBV DNA vaccines were designed to express envelope and cap...Duck hepatitis B virus(DHBV) shares many basic characteristics with hepatitis B virus(HBV) and is an attractive model for vaccine development. In this study, DHBV DNA vaccines were designed to express envelope and capsid fusion proteins to enhance the breadth of immune response in ducks. Attenuated Salmonella typhimurium(SL7207) was used as a carrier and adjuvant to boost the magnitude of immune response. Based on this strategy, novel DNA vaccines(SL7207-p VAX1-LC and SL7207-p VAX1-SC) were generated. Growth kinetics, genetic stabilities and relative transcription levels of the L, S and C genes introduced by these vaccine strains were measured before inoculation to guarantee safety and efficacy. The relative transcript levels of the CD4 and CD8 T genes and the antibody levels(Ig Y) in ducks receiving the vaccines were higher than those in single gene delivered groups. Additionally, the copy number of covalently closed circular DNA in hepatocytes after DHBV challenge also provided evidence that our fusion vaccines could enhance the protective efficiency against DHBV infection in ducks.展开更多
Hepatitis B virus(HBV)genotype B and C are two major genotypes that are prevalent in Asia and differ in natural history and disease progression.The impact of HBV genotypes on viral replication and protein expression h...Hepatitis B virus(HBV)genotype B and C are two major genotypes that are prevalent in Asia and differ in natural history and disease progression.The impact of HBV genotypes on viral replication and protein expression has been explored by the transfection of hepatoma cells with replication-competent HBV DNA,which mimics the later stages of the viral life cycle.However,the influence of HBV genotypes on the early events of viral infection remains undetermined,mainly due to the difficulties in obtaining sufficient infectious viral particles for infection assays.Here,we report that a high-titer HBV inoculum can be generated from the transient transfection-based cell model after optimizing transfection conditions and modifying the HBV-expressing construct.By performing in vitro infection assays using transiently transfected derived viruses,we found that clinical genotype C isolates possessed higher infectivity than genotype B isolates.Moreover,we identified a naturally occurring mutation sL21S in small hepatitis B surface protein,which markedly decreased the infectivity of HBV genotype C isolates,but not that of genotype B isolates.In summary,using infectious viral particles provided by the optimized transient transfection-based cell model,we have been able to investigate a wide range of HBV variants on viral infectivity,which may contribute to our understanding of the reasons for different clinical outcomes in HBV infections and the development of therapeutic drugs targeting the early stages of HBV life cycle.展开更多
基金supported by the National Key Technology R&D Program of China(2015BAD12B05)the earmarked fund for China Agricultural Research System(CARS-43-8)+1 种基金the Integration and Demonstration of Key Technologies for Duck Industry in Sichuan Province,China(2014NZ0030)the Sichuan Province Research Programs,China(2014-002)
文摘Duck hepatitis B virus(DHBV) shares many basic characteristics with hepatitis B virus(HBV) and is an attractive model for vaccine development. In this study, DHBV DNA vaccines were designed to express envelope and capsid fusion proteins to enhance the breadth of immune response in ducks. Attenuated Salmonella typhimurium(SL7207) was used as a carrier and adjuvant to boost the magnitude of immune response. Based on this strategy, novel DNA vaccines(SL7207-p VAX1-LC and SL7207-p VAX1-SC) were generated. Growth kinetics, genetic stabilities and relative transcription levels of the L, S and C genes introduced by these vaccine strains were measured before inoculation to guarantee safety and efficacy. The relative transcript levels of the CD4 and CD8 T genes and the antibody levels(Ig Y) in ducks receiving the vaccines were higher than those in single gene delivered groups. Additionally, the copy number of covalently closed circular DNA in hepatocytes after DHBV challenge also provided evidence that our fusion vaccines could enhance the protective efficiency against DHBV infection in ducks.
基金supported by grants of the National Youth Natural Science Foundation of China,China(82102380)the Youth Natural Science Foundation of Jiangsu Province(BK20200126)the National Youth Natural Science Foundation of China,China(81602400)。
文摘Hepatitis B virus(HBV)genotype B and C are two major genotypes that are prevalent in Asia and differ in natural history and disease progression.The impact of HBV genotypes on viral replication and protein expression has been explored by the transfection of hepatoma cells with replication-competent HBV DNA,which mimics the later stages of the viral life cycle.However,the influence of HBV genotypes on the early events of viral infection remains undetermined,mainly due to the difficulties in obtaining sufficient infectious viral particles for infection assays.Here,we report that a high-titer HBV inoculum can be generated from the transient transfection-based cell model after optimizing transfection conditions and modifying the HBV-expressing construct.By performing in vitro infection assays using transiently transfected derived viruses,we found that clinical genotype C isolates possessed higher infectivity than genotype B isolates.Moreover,we identified a naturally occurring mutation sL21S in small hepatitis B surface protein,which markedly decreased the infectivity of HBV genotype C isolates,but not that of genotype B isolates.In summary,using infectious viral particles provided by the optimized transient transfection-based cell model,we have been able to investigate a wide range of HBV variants on viral infectivity,which may contribute to our understanding of the reasons for different clinical outcomes in HBV infections and the development of therapeutic drugs targeting the early stages of HBV life cycle.
