Interaction of avian sarcoma/leukemia viruses with heterologous hosts: inference for host-range and some pathogenic...

Although there are substantial differences between retroviruses originating from avian and primate species, a comparison of these two different biological systems reveals that interaction of these retroviruses with heterologous hosts involves similar biological principles. Retroviral isolates with high replicative capacity in natural targets (e.g. CD4+ lymphocytes and macrophages for human immunodeficiency viruses (HIVs) can infect other cell types [e.g. CD- astrocytes, follicular dendritic cells (FDC) in vivo and/or CD4+ neoplastic T cells in vitro] as well. These viral isolates may have a potential of infecting heterologous cells in vitro and can enlarge their host-range by establishing infection in other species, distantly related. Strains of avian sarcoma/leukemia viruses (ASLV) originating from their natural hosts, chickens, and infectious for other avian species, ducks, can frequently infect mammals (rodents). Similarly, HIV-1 strains infectious for chimpanzees possess capacity of establishing chronic infection in pig-tailed macaques. The broad host-range of retroviral isolates in both viral 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 primary HIV-1 isolates is evaluated by infection of neoplastic CD4+ permanent cell line, MT2, and serves as a predictive marker of progression of the viral infection toward AIDS.