INTERACTION OF AVIAN-SARCOMA LEUKEMIA VIRUSES WITH HETEROLOGOUS HOSTS- INFERENCE FOR HOST-RANGE AND SOME PATHOGENIC PROPERTIES OF HUMAN IMMUNODEFICIENCY VIRUSES

Although there are substantial differences between retroviruses origin ating from avian and primate species, a comparison of these two differ ent biological systems reveals that interaction of these retroviruses with heterologous hosts involves similar biological principles. Retrov iral isolates with high replicative capacity in natural targets (e.g. CD4(+) lymphocytes and macrophages for human immunodeficiency viruses (HIVs) call infect other cell types [e.g. CD- astrocytes, follicular d endritic cells (FDC) in vivo and/or CD4(+) neoplastic T cells in vitro ] as well. These viral isolates may have a potential of infecting hete rologous cells in vitro and carl enlarge their host-range by establish ing infection in other species, distantly related. Strains of avian sa rcoma/leukemia viruses (ASLV) originating from their natural hosts, ch ickens, and infectious for other avian species, ducks, carl frequently infect mammals (rodents). Similarly, HIV-1 strains infectious for chi mpanzees possess capacity of establishing chronic infection in pig-tai led macaques. The broad host-range of retroviral isolates in both vira l systems is accompanied by presence of additional structures in viral envelope. These novel or additional envelope structures may recognize alternate viral receptor(s). Moreover, the enlarged host range of pri mary HIV-1 isolates is evaluated by infection of neoplastic CD4(+) per manent cell line, MT2, and serves as a predictive marker of progressio n of the viral infection toward AIDS.