Heat-labile, complement-like factor(s) of animal sera prevent(s) HIV-1 infectivity in vitro.

We studied inactivation of HIV-1 by fresh sera of animals. We found that while fresh sera of humans and chimpanzees (among others) did not have antiviral activity, fresh sera of several other mammals, especially those of rodents and felines, showed a dose-dependent viral-inactivating property against cell-free HIV-1; these sera were also capable of inactivating virus preadsorbed to cells, similar to neutralizing antibodies