Differences in neutralization of simian lentivirus (SIVMAC) in lymphocyte and macrophage cultures

Comparison of neutralization of SIVmac251 in primary macrophage cultures with neutralization in lymphocytes (CEM174 cells) showed that neutralizing antibodies induced by SIV251 in infected rhesus macaques protected both macrophages and T lymphocytes against infection when the virus was preincubated with the antibodies. In macrophages, the neutralizing antibodies also protected against infection when added 1 hour after the virus. Addition of antisera to macrophages between 24 and 48 hours after virus inoculation resulted in infection with continuous release of small amounts of p24 into the supernatant fluids but these antibody-treated cultures failed to exhibit cytopathic virus replication. In contrast, the same neutralizing antisera did not protect lymphocytes against infection and subsequent cytopathic replication of the virus when added only 1 hour after virus inoculation. This distinction in the effect that neutralizing antibodies had on the development of cytopathic infection in lymphocytes and macrophages when added after virus inoculation, suggests that they could alter the dynamics of virus replication and therefore the pathogenesis of disease.