Growth ability in simian cells of monkey cell-tropic HIV-1 is greatly affected by downstream region of the vif gene

To obtain monkey-tropic (mt) HIV-1 derivatives with distinct biological characteristics and to improve the viral growth property, we have generated several variants from a prototype mt HIV-1 designated NL-DT5R (X4-tropic). The prototype HIV-1 contains a portion of gag and entire vif genes from SIVmac in its genome. The two derivatives carrying 3’ half-genomic region of the SF162 (R5-tropic) or 89.6 (dual-tropic) isolate displayed very retarded or no viral growth, respectively, in a simian cell line HSC-F. In contrast, the three clones containing a part of env gene (encoding the V1-V4 region) from SF162, YU-2 (R5-tropic) or 89.6 showed different growth kinetics in HSC-F cells, although they grew somewhat more poorly than the NL-DT5R. Comparison of various viral proteins potentially involved in the different biological properties has revealed that, while amino acid sequences of Tat, Rev, Vpr, Vpu and Nef are quite conserved among the clones, those in the surface (SU) region of Env are relatively heterologous. Our data described here have shown that the 3’ half of viral genome other than gag and vif genes greatly affects the growth property of mt HIV-1 in simian cells.