Characterization and phylogenetic analysis of Varicella-zoster virus strains isolated from Korean patients

Varicella zoster virus mRNA vaccine candidate induced superior cellular immunity and comparable humoral and Fc-mediated immunity compared to the licensed subunit vaccine in a mouse model

The threat of herpes zoster (HZ) is increasing, particularly in the elderly and immunocompromised individuals. Although two platform vaccines are currently available for HZ prevention, the low effectiveness of the live attenuated varicella-zoster virus vaccine (Zostavax®), and the high reactogenicity and limited supply of the AS01 adjuvant gE subunit vaccine (Shingrix®) indicate that, the development of more effective and safe vaccines is required. Compared to conventional vaccines, mRNA vaccines offer the advantages of faster production and generally do not require adjuvants. However, no authorized mRNA vaccine is currently available for HZ. Therefore, we aimed to prepare a gE mRNA vaccine and evaluate the immunogenicity compared with the two commercial vaccines in mice. The gE mRNA vaccine elicited a robust humoral immune response, as measured by an enzyme-linked immunosorbent assay and the fluorescent antibody to membrane antigen test. The mRNA vaccine binding antibody level was comparable to that of Shingrix® and significantly higher than that of Zostavax®. In contrast, in cellular immune responses, which were evaluated by ELISpot assays and intracellular cytokine staining assay, the VZV gE mRNA vaccine induced significantly higher responses than Zostavax® and Shingrix®. In addition, the antibody-dependent cellular phagocytosis activity of the gE mRNA vaccine was comparable to that of the commercial vaccines. However, the highest antibody-dependent cellular cytotoxicity response was achieved by Shingrix®, followed by gE mRNA and then Zostavax®. Our results demonstrate that the mRNA HZ vaccine candidate elicited robust immunogenicity, especially in cellular immunity, and shows a promising potential for HZ prevention.

Immunological characteristics of MAV/06 strain of varicella-zoster virus vaccine in an animal model

BACKGROUND

Varicella-zoster virus (VZV) is a pathogen that causes chickenpox and shingles in humans. Different types of the varicella vaccines derived from the Oka and MAV/06 strains are commercially available worldwide. Although the MAV/06 vaccine was introduced in 1990s, little was known about immunological characteristics.

RESULTS

Here, we evaluated B and T cell immune response in animals inoculated with the Oka and MAV/06 vaccines as well as a new formulation of the MAV/06 vaccine. A variety of test methods were applied to evaluate T and B cell immune response. Plaque reduction neutralization test (PRNT) and fluorescent antibody to membrane antigen (FAMA) assay were conducted to measure the MAV/06 vaccine-induced antibody activity against various VZVs. Glycoprotein enzyme-linked immunosorbent assay (gpELISA) was used to compare the degree of the antibody responses induced by the two available commercial VZV vaccines and the MAV/06 vaccine. Interferon-gamma enzyme-linked immunosorbent spot (IFN-γ ELISpot) assays and cytokine bead array (CBA) assays were conducted to investigate T cell immune responses. Antibodies induced by MAV/06 vaccination showed immunogenicity against a variety of varicella-zoster virus and cross-reactivity among the virus clades.

CONCLUSIONS

It is indicating the similarity of the antibody responses induced by commercial varicella vaccines and the MAV/06 vaccine. Moreover, VZV-specific T cell immune response from MAV/06 vaccination was increased via Th1 cell response. MAV/06 varicella vaccine induced both humoral and cellular immune response via Th1 cell mediated response.

Human herpesvirus diversity is altered in HLA class I binding peptides

Herpesviruses are ubiquitous, genetically diverse DNA viruses, with long-term presence in humans associated with infrequent but significant pathology. Human leukocyte antigen (HLA) class I presents intracellularly derived peptide fragments from infected tissue cells to CD8+ T and natural killer cells, thereby directing antiviral immunity. Allotypes of highly polymorphic HLA class I are distinguished by their peptide binding repertoires. Because this HLA class I variation is a major determinant of herpesvirus disease, we examined if sequence diversity of virus proteins reflects evasion of HLA presentation. Using population genomic data from Epstein–Barr virus (EBV), human cytomegalovirus (HCMV), and Varicella–Zoster virus, we tested whether diversity differed between the regions of herpesvirus proteins that can be recognized, or not, by HLA class I. Herpesviruses exhibit lytic and latent infection stages, with the latter better enabling immune evasion. Whereas HLA binding peptides of lytic proteins are conserved, we found that EBV and HCMV proteins expressed during latency have increased peptide sequence diversity. Similarly, latent, but not lytic, herpesvirus proteins have greater population structure in HLA binding than nonbinding peptides. Finally, we found patterns consistent with EBV adaption to the local HLA environment, with less efficient recognition of EBV isolates by high-frequency HLA class I allotypes. Here, the frequency of CD8+ T cell epitopes inversely correlated with the frequency of HLA class I recognition. Previous analyses have shown that pathogen-mediated natural selection maintains exceptional polymorphism in HLA residues that determine peptide recognition. Here, we show that HLA class I peptide recognition impacts diversity of globally widespread pathogens.