We have continued our studies on examining the development of AIDS in a chimpanzee (C499) infected with three isolates of HIV-1.  Virus derived from a second chimpanzee (C455), which received a transfusion from C499, was used for molecular characterization along with virus from C499.  Infectious molecular clones of each virus were derived.  Sequence analysis of these clones suggested that they were recombinants between two of the three viruses used to inoculated C499, HIV-1SF2 and HIV-1LAV1b.  Replicative abilities of these viruses were assessed in primary PBMC and macrophages.  These studies demonstrated the increased ability of these viruses to induce cytopathic effects in PBMC.  Additionally, enhanced replicative abilities were observed in macrophage cultures.  Studies of these viruses will continue in vitro in order to possibly define characteristics which may contribute to in vivo pathogenesis.  FUNDING NIH / AI40879 $135,465 6/01/97 - 5/31/01 PUBLICATIONS Mwaengo, D.M. and Novembre, F.J. Molecular cloning and characterization of viruses isolated from chimpanzees with pathogenic HIV-1 infection.  J Virol 72:8976-8987, 1998.  P51RR00165-38 1/1/1998 - 12/31/1998 Yerkes Regional Primate Research Center