Recombinant Vaccinia DIs Expressing Simian Immunodeficiency Virus Gag and Pol in Mammalian Cells Induces Efficient Cellular Immunity as a Safe Immunodeficiency Virus Vaccine Candidate

Abstract

A highly attenuated vaccinia virus substrain of Dairen‐I (DIs) shows promise as a candidate vector for eliciting positive immunity against immune deficiency virus. DIs was randomly obtained by serial 1‐day egg passages of a chorioarantoic membrane‐adapted Dairen strain (DIE), resulting in substantial genomic deletion, including various genes regulating the virus‐host‐range. To investigate the impact of that deletion and of the subsequent insertion of a foreign gene into that region of DIs on the ability of the DIs recombinant to induce antigen‐specific immunity, we generated a recombinant vaccinia DIs expressing full‐length gag and pol genes of simian immunodeficiency virus (SIV) (rDIsSIV gag/pol) and studied the biological and immunological characteristics of the recombinant natural mutant. The rDIsSIV gag/pol developed a tiny plaque on the chick embryo fibroblast (CEF). Viral particles of rDIsSIV gag/pol as well as SIV Gag‐like particles were electromicroscopically detected in the cytoplasm. Interestingly, the recombinant DIs strain grows well in CEF cells but not in mammalian cells. While rDIsSIV gag/pol produces SIV proteins in mammalian HeLa and CV‐1 cells, recombinant modified vaccinia Ankara strain (MVA) expressing SIV gag and pol genes (MVA/SIV239gag/pol) clearly replicates in HeLa and CV‐1 cell lines under synchronized growth conditions and produces the SIV protein in all cell lines. Moreover, intradermal administration of rDIsSIV gag/pol or of MVA/SIV239gag/pol elicited similar levels of IFN‐γ spot‐forming cells specific for SIV Gag. If the non‐productive infection characteristically induced by recombinant DIs is sufficient to trigger immune induction, as we believe it is, then a human immunodeficiency virus vaccine employing the DIs recombinant would have the twin advantages of being both effective and safe.

The Evolution of Poxvirus Vaccines

“…Insertion of HIV-1 Gag gene in the deleted region of DIs induced high levels of cytotoxic T lymphocytes in immunized mice [263]. Furthermore, a recombinant VACV DIs expressing simian immunodeficiency virus (SIV) Gag and Pol antigens induces SIV-specific cellular and humoral immuneresponsesin mice [264,265] or immunized non-human primates [266,267]. These results suggest that recombinant VACV DIs is a safe, efficient, transient replication-deficient viral vector, which can be used in a vaccine regimen for HIV-1 vaccine development.…”

Smallpox vaccines for biodefense

“…Similar to NYVAC, Dairen-I has served as a useful vector in the development of vaccines against mycobacterium, HIV, SARS and other pathogens. [78][79][80] A variety of other attenuated vaccinia virus strains have been created through the selected deletion or alteration of host range genes, virulence factors and immunomodulatory genes. [81][82][83][84][85][86][87] These recombinant vaccinia strains have been shown to grow to lower titers in various organs, and/or exhibit less toxicity and morbidity in immunocompromised animal models.…”

Intradermal Delivery of Recombinant Vaccinia Virus Vector DIs Induces Gut‐Mucosal Immunity

“…The first step was to assess whether intradermal injection of rDIsSIV gag induces Gag‐specific IFN‐γ‐producing CD8 + T cells in mucosal and systemic tissues. Although the BCG vector itself non‐specifically enhances the levels of some cytokines [33], the DIs empty vector and rDIsLacZ scarcely stimulated IFN‐γ‐production, and the number of IFN‐γ SFC per 10 6 cells was less than 32 in intradermally injected mice [14] and intramuscularly injected non‐human primates [12] in our previous studies. Moreover, the calculated number of Gag‐specific IFN‐γ SFC from naive mice was < 15 per 10 6 CD8 + T cells.…”

“…The replication‐deficient vaccinia virus, DIs, is a candidate viral vector; and it is a safe and highly attenuated mutant of the vaccinia virus [6–9]. When recombinant DIs (rDIs) encoding foreign antigens (Ag) was intravenously [9, 10], intramuscularly [11, 12], subcutaneously [13], or intradermally [14] injected, Ag‐specific systemic immunity was induced in mice and non‐human primates.…”