Summary auto-generated
Researchers constructed a recombinant Oka varicella-zoster virus (VZV) vaccine expressing hepatitis B virus surface antigen (HBs) by inserting the HBs gene into the viral thymidine kinase gene. The recombinant virus successfully expressed HBs in infected cell cytoplasm, producing 26K and 30K molecular weight proteins in cells and 30K and 35K proteins in culture supernatants. HBs was secreted as 20-25 nm particles and remained stable through multiple passages in culture. When tested in guinea pigs, a single dose of the recombinant vaccine induced robust antibody responses to both VZV and HBs, with HBs antibody titers comparable to those from a yeast-derived HBs subunit vaccine. The recombinant virus maintained the immunogenicity of the parent Oka vaccine against VZV while successfully adding HBs immunogenicity, suggesting potential as a combined vaccine against both varicella and hepatitis B infection.
Key findings
- The recombinant Oka varicella vaccine expressing HBs gene was successfully constructed and expressed stable, biologically active HBs protein throughout multiple in vitro passages
- Recombinant virus-infected cells produced HBs proteins that were secreted into culture medium as particles similar in size to natural 22 nm HBV particles found in infected serum
- A single immunization dose of recombinant virus induced antibody responses to both VZV and HBs in guinea pigs, with HBs-specific titers equivalent to those elicited by yeast-produced HBs subunit vaccine
- The recombinant virus maintained full immunogenicity to VZV while successfully expressing and presenting HBs, supporting its potential as a bivalent live vaccine candidate
This summary was generated automatically from the article PDF and is not part of the original publication. Refer to the PDF for the authoritative text.
Abstract
Recombinant Oka varicella vaccine expressing hepatitis B virus (HBV) surface antigen (HBs) was constructed by inserting the HBs gene into the viral thymidine kinase (TK) gene and was examined for its immunogenicity in guinea-pigs. The HBs gene encoding 25 amino acids of preS2 and the whole of the S region was inserted into the TK gene of the cloned plasmid. The chimeric plasmid DNA and Oka varicella vaccine DNA were cotransfected and recombinant virus was isolated after immunofluorescence screening using a monoclonal antibody to HBs and a fluorescein-conjugated anti-mouse antibody. Expression of viral HBs was detected in the cytoplasm of infected cells and was stable over several repeated passages in vitro. The recombinant virus expressed 26K and 30K HBs molecules in infected cells and the culture supernatant contained 30K and 35K HBs molecules. HBs was purified at a density of 1.20 g/ml from the culture supernatants. The recombinant virus induced an antibody response to HBs as well as to varicella-zoster virus (VZV) in guinea-pigs, and the antibody titre to HBs was comparable to that induced by a recombinant HBs subunit vaccine produced in yeast. Thus a single dose of live recombinant Oka varicella vaccine could induce good immunity to VZV and HBs. The recombinant Oka varicella vaccine expressing HBs may be a good candidate for a combined HBV and VZV vaccine.
† Present address: Department of Virology, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-01, Japan.