Comparison of early plasma RNA loads in different macaque species and the impact of different routes of exposure on SIV/SHIV infection

Various simian immunodeficiency virus (SIV)(sm/mac) and simian/human immuno deficiency virus (SHIV) strains are used in different macaque species to st udy AIDS pathogenesis, as well as to evaluate candidate vaccine and anti-re troviral drugs efficacy. In this study we investigated the effect of route of infection, species of macaques and nature of virus stock on early plasma viral RNA load. We monitored the plasma RNA concentrations of 63 rhesus (M acaca mulatta) and cynomolgus macaques (Macaca fascicularis) infected with well-characterised virus stocks administered either by oral, rectal, vagina l or intravenous (i.v.) routes. In SIVmac-infected macaques, no significant difference in plasma RNA loads was observed between the rectal, oral and i .v. routes of infection. Cynomolgus macaques developed lower steady state S IV plasma RNA concentrations compared with rhesus macaques and no significa nt difference was observed between rectal and i.v. routes of infection. In SHIV89.6p-infected macaques, no difference between species or between route of infection was observed with this particular chimeric virus.