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Novel MVA Vector Expressing Anti-apoptotic gene, B13R, Delays Apoptosis and Enhances Humoral Responses

ABSTRACT: Modified vaccinia virus Ankara (MVA) has been explored as a vaccine vector for use against infectious diseases and cancer. MVA is an immunogenic, attenuated poxvirus capable of eliciting robust cellular and humoral responses in pre-clinical animal models and in patients. However, upon infection with MVA, cells undergo rapid apoptosis leading to faster clearance of recombinant antigens. The fragmentation of the anti-apoptotic gene B13R in MVA could contribute to this effect. Here, we replaced the fragmented B13R with a functional version and observed that MVA-B13R infected HeLa cells and muscle cell lines delayed caspase 3 activation compared to MVA indicating slower progression of apoptosis. For immunogenicity studies, mice were intramuscularly immunized with recombinant MVA or MVA-B13R expressing SIV Gag, Pol and HIV Env (SHIV). We observed higher Env-specific humoral responses from MVA-B13R SHIV compared to MVA SHIV mice. To determine differences in the innate immune response that may have contributed to the augmented humoral response, we performed RNA-Seq analysis on draining lymph node cells after immunization. Gene set enrichment analysis from day 1 after immunization showed that MVA-B13R SHIV immunizations were associated with a negative enrichment for type I and II interferon responses compared to MVA SHIV mice indicating MVA-B13R SHIV induces a delayed anti-viral interferon response that may lead to the enhanced humoral response observed. Taken together, these results demonstrate that restoring B13R functionality in MVA significantly delays MVA-induced apoptosis, augments Env-specific antibody responses, and is associated with reduced interferon-alpha and interferon-gamma responses induced after vaccination.

ORGANISM(S): Mus musculus

PROVIDER: GSE119884 | GEO | 2018/11/27

REPOSITORIES: GEO

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Project description:We sought to test whether vaccine-induced immune responses could protect rhesus macaques (RMs) against upfront heterologous challenges with an R5 simian-human immunodeficiency virus, SHIV-2873Nip. We immunized the RMs with recombinant Env proteins heterologous to the challenge virus. For induction of immune responses against Gag, Tat, and Nef, we explored a strategy of immunization with overlapping synthetic peptides (OSP). The immune responses against Gag and Tat were finally boosted with recombinant proteins. The vaccinees and a group of ten control animals were given five low-dose intrarectal (i.r.) challenges with SHIV-2873Nip. All controls and seven out of eight vaccinees became systemically infected; there was no significant difference in viremia levels of vaccinees vs. controls. Prevention of viremia was observed in one vaccinee which showed strong boosting of virus-specific cellular immunity during virus exposures. The protected animal showed no challenge virus-specific neutralizing antibodies in the TZM-bl or A3R5 cell-based assays and had low level ADCC activity after the virus exposures. Microarray data strongly supported a role for cellular immunity in the protected animal. Our study represents a case of protection against heterologous tier 2 SHIV-C by vaccine-induced, virus-specific cellular immune responses. For the protected RM, blood was collected before vaccination, on the day of first virus exposure and six weeks after last virus challenge. Lymph node and rectal pinch biopsies were performed before vaccination and six weeks after last virus challenge. Blood was collected in tempus tubes and processed immediately according to the manufacturer’s instructions and stored at -80C. The biopsy specimens were cut into small pieces and immediately placed into RNAlater solution (Qiagen, Valencia, CA) and also stored at -80C. Total RNA from blood, lymph node and rectal biopsies was extracted using RNAeasy extraction kits (Qiagen, Valencia, CA). cDNA labeling, hybridization, staining and scanning were performed according to the manufacturer’s instructions (Affymetrix, Santa Clara, CA) for rhesus gene expression arrays.

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Novel MVA Vector Expressing Anti-apoptotic gene, B13R, Delays Apoptosis and Enhances Humoral Responses

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