Prime boost HIV vaccination with recombinant influenza virus vectors stimulates specific and mucosal CD8+ T cell immune response in BALB/c mice

HIV/AIDS continues to be a significant medical problem worldwide. An effective and safe vaccine remains a high priority. Most HIV vaccine candidates to date have failed to elicit effective immune responses that are necessary to control HIV infection. The results of a promising phase III trial conducted in Thailand using a recombinant canarypox vector vaccine (ALVAC) expressing HIV Gag in combination with recombinant HIVEnv glycoprotein gp120 (AIDSVAX), showed 31.2% efficacy in humans and raised the prospect of a protective vaccine. The most recommended HIV vaccines are focusing on inducing specific CD8+ T as a critical immune response to control progression and dissemination of HIV virus from the site of infection into different mucosal compartments of the body.This study project used influenza viruses as a mucosal live vaccine vector to stimulate effective CD8+ T cell immunity. Recombinant influenza A viruses, H3N2 (HK-X31) and H1N1 (A/PR8/8/34) expressing defined mouse HIV-1 CD8+ T cell epitopes (H-2Kd Gag197-205 and H-2Kd Tat17-25) in the neuraminidase (NA) stalk were generated using reverse genetics and administered as a prime-boost vaccine within various mucosal routes of vaccination, intranasal-intranasal, intravaginal-intravaginal, intranasalintravaginal and intravaginal-intranasal vaccination in BALB/C mice. Following those prime-boost vaccinations, tetramer and intracellular cytokine staining assays used for the detection of specific CD8+ T cell immune response in harvested organs, spleen, bronchoalveolar lavage (BAL), mediastinal and inguinal lymph nodes. In addition, mucosal HIV-specific CD8+ T cells were detected using specific anti-mouse CD8α antibodies directed against specific integrins (LPAM-1 and CD103). Moreover, the level of specific cytokines, such as interleukin15 (IL-15) detected within specific mucosal CD8+ T cells for the detection of the migrated HIV-1 Gag+ CD8+ T cells.Our result showed there was an induction of CD8+ T cells targeted H-2KdGag197-205, compared to no CD8+ T cell responses specific for H-2Kd Tat17-25 in recombined influenza-HIV vaccinated BALB/c mice. Also, comparable HIV and endogenous influenza-specific CD8+ T cell responses following intranasallyintranasally prime-boost vaccination in harvested lymphoid tissues, spleen, bronchoalveolar lavage, and mediastinal lymph nodes compared to inguinal lymph nodes which included a high proportion of specific CD8+ T cell immune response following intravaginal-intravaginal prime-boost infection. Moreover, a proportion of these cells isolated from mice infected with recombinant influenza-HIV vaccine intranasally-intranasally primeboost expressed mucosal surface integrins, especially LPAM-1(α4β7) of local and distal lymph nodes higher than the levels observed following intravaginal vaccination. In addition, mucosal LPAM-1+HIV-Gag197-205+ CD8+ T cells harvested of intranasal prime-boost vaccinated mice were recognized by a high expression of IL15 compared to LPAM-1-HIVGag197-205+ CD8+ T cells.We conclude that the intranasal prime-boost vaccination as one of the mucosal routes of vaccination using recombinant influenza viruses as mucosal viral vectors of HIV vaccine in BALB/c mice has an important role in stimulating both specific and mucosal CD8+ T cells within a high level and these cells would be important for migration of mucosal specific CD8+ T cells given the mucosal acquisition of HIV infection and control of HIV-1 virus dissemination through mucosal compartments.