Neutralization of primary HIV isolates

The aim of this study was to search for immune responses that correlated with protection by establishing a sensitive system for the detection of neutralizing antibodies against primary viral isolates. Sera from 6 chimpanzees vaccinated against HIV-1, 14 Rhesus macaques immunized against HIV-1 and 8 HIV-2 Rhesus macaques immunized against HIV-2 were then tested in this system against a "long-term" HIV-1$\sb{\rm MN}$ primary isolate passaged multiple times in PBMC's, as well as a number of true primary isolates at low passage number. A correlation was seen between a neutralizing antibody response against the "long-term" HIV-1$\sb{\rm MN}$ primary isolate and protection against viral infection in the chimpanzee model. No such correlation could be seen in the macaque models. No neutralizing antibody response was evident in either the chimpanzee or the macaque models against any of the true primary isolates. Thus, no clear immune correlation could be seen in this system against primary isolates.