Preclinical Studies of a Modified Vaccinia Virus Ankara-Based HIV Candidate Vaccine: Antigen Presentation and Antiviral Effect

Unité Virus et Immunite, Institut Pasteur, URA CNRS 3015, Paris, France.
Journal of Virology (Impact Factor: 4.44). 03/2010; 84(10):5314-28. DOI: 10.1128/JVI.02329-09
Source: PubMed


Poxvirus-based human immunodeficiency virus (HIV) vaccine candidates are currently under evaluation in preclinical and clinical trials. Modified vaccinia virus Ankara (MVA) vectors have excellent safety and immunogenicity records, but their behavior in human cell cultures remains only partly characterized. We studied here various virological and immunological aspects of the interactions of MVA-HIV, a vaccine candidate developed by the French National Agency for AIDS Research (ANRS), with primary human cells. We report that MVA-HIV infects and drives Gag expression in primary macrophages, dendritic cells (DCs), and epithelial and muscle cells. MVA-HIV-infected DCs matured, efficiently presented Gag, Pol, and Nef antigens, and activated HIV-specific cytotoxic T lymphocytes (CTLs). As expected with this type of vector, infection was cytopathic and led to DC apoptosis. Coculture of MVA-HIV-infected epithelial cells or myotubes with DCs promoted efficient Gag antigen major histocompatibility complex class I (MHC-I) cross-presentation without inducing direct infection and death of DCs. Antigen-presenting cells (APCs) infected with MVA-HIV also activated HIV-specific CD4(+) T cells. Moreover, exposure of DCs to MVA-HIV or to MVA-HIV-infected myotubes induced type I interferon (IFN) production and inhibited subsequent HIV replication and transfer to lymphocytes. Altogether, these results show that MVA-HIV promotes efficient MHC-I and MHC-II presentation of HIV antigens by APCs without facilitating HIV replication. Deciphering the immune responses to MVA in culture experiments will help in the design of innovative vaccine strategies.

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Available from: Marion Desdouits, Mar 17, 2014
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    • "Our data revealed that the expression of intracellular Gag was dose-dependent and we also found that MVA and MVA-B infection produced a rapid cytopathic effect on the infected cells, being this phenomenon associated with direct infection of the cells. These results are consistent with previous reports using MDDC from healthy individuals infected with MVA vectors expressing HIV antigens [17], [18], [20]. In our study, we extended infection up to 72 hours, when we observed a nearly null percentage of viable cells infected with both MVA and MVA-B. "
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    ABSTRACT: Currently, MVA virus vectors carrying HIV-1 genes are being developed as HIV-1/AIDS prophylactic/therapeutic vaccines. Nevertheless, little is known about the impact of these vectors on human dendritic cells (DC) and their capacity to present HIV-1 antigens to human HIV-specific T cells. This study aimed to characterize the interaction of MVA and MVA expressing the HIV-1 genes Env-Gag-Pol-Nef of clade B (referred to as MVA-B) in human monocyte-derived dendritic cells (MDDC) and the subsequent processes of HIV-1 antigen presentation and activation of memory HIV-1-specific T lymphocytes. For these purposes, we performed ex vivo assays with MDDC and autologous lymphocytes from asymptomatic HIV-infected patients. Infection of MDDC with MVA-B or MVA, at the optimal dose of 0.3 PFU/MDDC, induced by itself a moderate degree of maturation of MDDC, involving secretion of cytokines and chemokines (IL1-ra, IL-7, TNF-α, IL-6, IL-12, IL-15, IL-8, MCP-1, MIP-1α, MIP-1β, RANTES, IP-10, MIG, and IFN-α). MDDC infected with MVA or MVA-B and following a period of 48 h or 72 h of maturation were able to migrate toward CCL19 or CCL21 chemokine gradients. MVA-B infection induced apoptosis of the infected cells and the resulting apoptotic bodies were engulfed by the uninfected MDDC, which cross-presented HIV-1 antigens to autologous CD8(+) T lymphocytes. MVA-B-infected MDDC co-cultured with autologous T lymphocytes induced a highly functional HIV-specific CD8(+) T cell response including proliferation, secretion of IFN-γ, IL-2, TNF-α, MIP-1β, MIP-1α, RANTES and IL-6, and strong cytotoxic activity against autologous HIV-1-infected CD4(+) T lymphocytes. These results evidence the adjuvant role of the vector itself (MVA) and support the clinical development of prophylactic and therapeutic anti-HIV vaccines based on MVA-B.
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    • "However, the presence of viral inclusions suggests that at least in mDC and pDC, there might have been translation of the late ATI protein (Osterrieder et al., 1994; Patel et al., 1986). Infection by canarypox virus, VACV or MVA of MDDCs leads to DC apoptosis (Brandler et al., 2010; Chahroudi et al., 2006; Zhang et al., 2007), and VACV infection of MDDCs leads to loss of viability as measured by trypan blue exclusion (Engelmayer et al., 1999). In contrast, we found that the numbers of viable DCs (assessed by trypan blue exclusion), was not altered by CPXV infection (Table 1). "
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