Distinct Roles of Vaccinia Virus NF-κB Inhibitor Proteins A52, B15, and K7 in the Immune Response

Abstract

Poxviruses use a complex strategy to escape immune control, by expressing immunomodulatory proteins that could limit their use as vaccine vectors. To test the role of poxvirus NF-B pathway inhibitors A52, B15, and K7 in immunity, we deleted their genes in an NYVAC (New York vaccinia virus) strain that expresses HIV-1 clade C antigens. After infection of mice, ablation of the A52R, B15R, and K7R genes increased dendritic cell, natural killer cell, and neutrophil migration as well as chemokine/cytokine expression. Revertant viruses with these genes confirmed their role in inhibiting the innate immune system. To different extents, enhanced innate immune responses correlated with increased HIV Pol-and Gag-specific polyfunctional CD8 T cell and HIV Env-specific IgG responses induced by single-, double-, and triple-deletion mutants. These poxvirus proteins thus influence innate and adaptive cell-mediated and humoral immunity, and their ablation offers alternatives for design of vaccine vectors that regulate immune responses distinctly.IMPORTANCE Poxvirus vectors are used in clinical trials as candidate vaccines for several pathogens, yet how these vectors influence the immune system is unknown. We developed distinct poxvirus vectors that express heterologous antigens but lack different inhibitors of the central host-cell signaling pathway. Using mice, we studied the capacity of these viruses to induce innate and adaptive immune responses and showed that these vectors can distinctly regulate the magnitude and quality of these responses. These findings provide important insights into the mechanism of poxvirus-induced immune response and alternative strategies for vaccine vector design.KEYWORDS NF-B, NYVAC, T cell immunity, adaptive immunity, human immunodeficiency virus, immunomodulation, innate immunity, poxvirus, vaccines, vaccinia virus S everal vaccine strategies have been developed to improve immune responses to heterologous antigens expressed by attenuated poxvirus vectors (1). Given the limited effectiveness of the ALVAC poxvirus vector in the RV144 phase III HIV/AIDS clinical trial (2), the need remains to improve poxvirus vector capacity as an immunogen, to increase protection levels, and to understand how innate and adaptive immune responses can be regulated.The attenuated poxvirus strain NYVAC (New York vaccinia virus) has been used as a vaccine vector in HIV clinical trials (3,4). Studies in nonhuman primates showed that NYVAC expressing Env and/or the Gag-Pol-Nef (GPN) clade C HIV antigens elicited a balanced CD4/CD8 T cell response (5) or robust T cell immunity (6). In clinical trials in healthy volunteers and in chronically HIV-infected patients, NYVAC showed clear immunogenic potential to induce expansion of preexisting T cell responses as well as the appearance of newly detected polyfunctional CD8 T cell responses (7).

Deletion of Vaccinia Virus A40R Gene Improves the Immunogenicity of the HIV-1 Vaccine Candidate MVA-B

“…Results showed that the DNA-B/MVA-B ∆A40R immunization group presented significantly enhanced magnitude of the overall adaptive and memory HIV-1-specific CD4+ and CD8+ T cells expressing CD107a, IFN-γ, TNF-α, and/or IL-2 compared to DNA-B/MVA-B. These results further suggest the immunosuppressive role of MVA A40 protein, as deletions of well-known immunosuppressive VACV genes from MVA or NYVAC vectors expressing HIV-1 antigens have produced similar results [18,20,21,23,[69][70][71][74][75][76][77][78]. Furthermore, both immunization groups elicited an adaptive and memory HIV-1-specific T-cell immune response with a similar polyfunctional profile, and mainly TEM and to a lesser extent TE phenotypes.…”

“…Due to the lack of detection (using Western blot or immunofluorescence assays) of A40 protein when expressed from its natural locus in MVA or MVA-B viruses, we decided to reintroduce the MVA A40R gene into the HA locus of the MVA-B ∆A40R under the control of a stronger sE/L viral promoter. A similar strategy was used previously to generate NYVAC-based revertant viruses, which allowed us to demonstrate the important role of NFκB activation by VACV in enhancing neutrophil migration and HIV-1-specific T-cell responses [77,78]. Moreover, it has been reported that insertion of heterologous genes into the MVA HA locus does not affect the expression of neighboring MVA genes and the recombinant viruses generated are functional, indicating that the HA gene region is a suitable insertion site [89].…”

Characterization of virus-mediated immunogenic cancer cell death and the consequences for oncolytic virus-based immunotherapy of cancer

“…9). It should be noticed that the VV-encoded proteins A52, B15, and K7 are inhibitors of NF-kB and known to suppress chemokine/cytokine expression from immune cells 43 . Ad-and SFV4-mediated DC activation is immune stimulating as assessed by release of IFN-γ from model antigen-specific CD8 + T-cells.…”

Genes that control vaccinia virus immunogenicity

“…Многочисленные работы, посвященные делеции (удалению) генов иммуномодулирующих факторов VACV, позволили выявить некоторые вирусные гены, инактивация которых наряду с аттенуацией вируса приводит к увеличению его иммуногенности [43][44][45][46][47][48][49][50][51][52][53]. Как видим из данных, приведенных в табл.…”