Polarization of protective immunity induced by replication-incompetent adenovirus expressing glycoproteins of pseudorabies virus

Replication-incompetent adenoviruses expressing three major glycoproteins (gB, gC, and gD) of pseudorabies virus (PrV) were constructed and used to examine the ability of these glycoproteins to induce protective immunity against a lethal challenge. Among three constructs, recombinant adenovirus expressing gB (rAd-gB) was found to induce the most potent immunity biased to Th1-type, as determined by the IgG isotype ratio and the profile of the Th1/Th2 cytokine production. Conversely, the gC-expressing adenovirus (rAd-gC) revealed Th2-type immunity and the gD-expressing adenovirus (rAd-gD) induced lower levels of IFN-gamma and IL-4 production than other constructs, except IL-2 production. Mucosal delivery of rAd-gB induced mucosal IgA and serum IgG responses and biased toward Th2-type immune responses. However, these effects were not observed in response to systemic delivery of rAd-gB. In addition, rAd-gB appeared to induce effective protective immunity against a virulent viral infection, regardless of whether it was administered via the muscular or systemic route. These results suggest that administration of replication-incompetent adenoviruses can induce different types of immunity depending on the expressed antigen and that recombinant adenoviruses expressing gB induced the most potent Th1-biased humoral and cellular immunity and provided effective protection against PrV infection.

Flaviviruses Induce Pro-inflammatory and Anti-inflammatory Cytokines from Murine Dendritic Cells through MyD88-dependent Pathway

BACKGROUND: The genus Flavivirus consists of many emerging arboviruses, including Dengue virus (DV), Japanese encephalitis virus (JEV) and West Nile virus (WNV). Effective preventive vaccines remain elusive for these diseases. Mice are being increasingly used as the animal model for vaccine studies. However, the pathogenic mechanisms of these viruses are not clearly understood. Here, we investigated the interaction of DV and JEV with murine bone marrow-derived dendritic cells (bmDC). METHODS: ELISA and FACS analysis were employed to investigate cytokine production and phenotypic changes of DCs obtained from bone marrow following flavivirus infection. RESULTS: We observed that these viruses altered the cytokine profile and phenotypic markers. Although both viruses belong to the same family, JEV-infected bmDC produced anti-inflammatory cytokine (IL-10) along with pro-inflammatory cytokines, whereas DV infection induced production of large amounts of pro-inflammatory cytokines (IL-6 and TNF-alpha) and no IL-10 from murine bmDCs. Both flaviviruses also up-regulated the expression of co-stimulatory molecules such as CD40, CD80 and CD86. JEV infection led to down-regulation of MHC II expression on infected bmDCs. We also found that cytokine production induced by JEV and DV is MyD88-dependent. This dependence was complete for DV, as cytokine production was completely abolished in the absence of MyD88. With regard to JEV, the absence of MyD88 led to a partial reduction in cytokine levels. CONCLUSION: Here, we demonstrate that MyD88 plays an important role in the pathogenesis of flaviviruses. Our study provides insight into the pathogenesis of JEV and DV in the murine model.

In vivo CTL Activity Induced by Prime-boost Vaccination using Recombinant Vaccinia Virus and DNA Vaccine Expressing Epitope Specific for CD8+ T Cells

DNA vaccine approaches have been applied to generate the protective immunity against various pathogens. However, the strength of immune responses induced by DNA vaccine is weak compared with conventional vaccines. The primeboost vaccination using DNA vaccine and other viral vector has been suggested as one way to circumvent this limitation. In the present study, we used in vivo CTL activity assay to determine CD8+ T cell-mediated immunity induced by prime-boost vaccination with a DNA vaccine (gB498-505 DNA) and recombinant vaccinia virus (VVgB498-505) expressing gB498-505 epitope peptide (SSIEFARL) of herpes simplex virus type 1 (HSV-1) glycoprotein B (gB). The most potent in vivo CTL activity was induced in mice received VVgB498-505 when both gB498-505 and VVgB498-505 were used at priming step and boosted with the alternative vaccine vector expressing whole antigen protein (gBw). Priming with vaccine vector expressing gBw followed by the use of VVgB498-505 at boosting step also induced strong in vivo CTL activity. We also examined in vivo CTL activity after immunization of mice with epitope-expressing vaccine vector at both priming and boosting step. Curiously, in vivo CTL activity mediated by CD8+ T cells was strongly elicited at memory stage when animals were primed with VVgB498-505 and subsequently boosted with gB498-505 DNA. Because the use of VVgB498-505 at priming followed by boosting with gB498-505 DNA induced most optimal immunity, these results suggest that the order of vaccine type should be carefully considered when used vaccine type expressing only epitope for prime-boost vaccination.