Baboon As Model Of Hiv Heteroseual Transmission Using Shiv89.6p Chimera Virus

Abstract

Human Immunodeficiency Virus is predominantly transmitted in most parts of the world via heterosexual contact in men and women. The most urgently needed intervention is an effective vaccine(s) and microbiocides to prevent the vaginal transmission of HIV, as majority of women now in Africa acquired new infections through heterosexual route. Heterosexual transmission of HIV accounts for over 85% of all transmissions. The specific objectives of the study were to establish if Simian Human Immunodeficiency chimera virus can be transmitted from SHIV89.6p infected baboons via the genital mucosa through natural mating and experimentally through nontraumatic experimental inoculation. Twelve sexually mature baboons were grouped into four experimental groups in this study. In the 1 group, the study investigated if SHIV89.6p can be transmitted heterosexually through natural mating of SHIV89.6p -infected baboons. In this group, a male baboon was inoculated intravenously with SHIV89.6p and after 2 weeks allowed to mate with a naïve female while in the group 2, six sexually mature females were intravaginally inoculated with SHIV89.6p, 3 times a week for 3 weeks. In group 3, the study investigated if a pervaginally SHIV89.6p infected female baboon can transmit the SHIV89.6p to an uninfected male baboon through natural mating. In this experiment, the female baboon was inoculated with SHIV89.6p through a traumatic trans-vaginal mucosa method; after 2weeks, the female was paired with an uninfected male partner and lastly in-group 4, a female baboon was inoculated intravenously with SHIV89.6p and after 2 weeks allowed to mate with a naïve male. This study investigated if SHIV89.6p can be transmitted heterosexually through natural mating of SHIV89.6p infected baboons. Blood samples were obtained regularly from these animals to check for antibody profile and isolation of SHIV89.6p, from peripheral blood mononucleated cells. In addition, lymph node biopsies were obtained at two time points from each animal for the isolation of SHIV89.6p. through tissue culture. Results obtained from intravenous and perivaginal inoculated baboons shown persistent systemic infection as evidenced by virus recovery from blood and inguinal lymph node at various time points. The presence of SHIV89.6p proviral DNA was confirmed in the blood by PCR at week 15, 18, 26 post inoculation. In addition, anti- SHIV89.6p antibodies were consistently detected at various time points post inoculation and confirmed by Western blot. Uninfected male and female baboons that were paired mated with SHIV89.6p infected baboons remained seronegative throughout the entire experimental period. The results obtained from non-traumatic inoculated baboons revealed that, all baboons which were mated did not seroconvert. The results were ascertained by carrying out an antigen capture p27 and anti- SHIV89.6p -antibody Enzyme Linked Immunosorbent Assay from different time points. The results suggest that baboons do not readily get infected with HIV based on SHIV89.6p model, despite multiple genital exposures to SHIV89.6p hence not a good model for heterosexual transmission of SHIV89.6p.