Abstract
More than a decade ago, successful replication of hepatitis A virus (HAV) in cell culture opened the way to the development of live attenuated and inactivated vaccine candidates. Serial passages of HAV in cell culture led to attenuation as demonstrated by experiments in non-human primates. Several live vaccine candidates obtained through serial passages have been evaluated in volunteers. Significant improvements in the yield of viral antigen from infected cell cultures stimulated the development of killed vaccine candidates. These formalin-inactivated vaccines contain the viral capsid antigens assembled into viral particles. The immunogenic potential of the vaccine candidates depends strongly on the preservation of the configuration of the capsid proteins. Synthetic peptides covering immunogenic sequences of VP1 as well as soluble capsid proteins expressed as fusion proteins in Escherichia coli were therefore only weakly immunogenic when injected at high concentrations in rabbits. On the other hand, tamarin monkeys immunized with a live recombinant vaccinia expressing P1 were protected against virulent challenge. There are, however, considerable drawbacks related to the use of live vaccinia as a carrier virus. Chimeric polio-HAV VP1 viruses have been constructed. These hybrid viruses were not able to induce an immune response, probably because of configurational constraints of poliovirus on the inserted HAV epitopes. More recently, encouraging data on empty virus particles expressed in baculovirus and vaccinia virus systems have been reported.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.