In-vitro selection of HIV-1 variants resistant to non-nucleoside reverse transcriptase inhibitors in monocyte-derived macrophages

Unlike the selection of HIV-1 variants resistant to anti-retroviral drugs in human peripheral blood mononuclear cells and T cell lines, induction of resistance in monocyte-derived macrophages has not been widely studied. Since macrophages serve as a potential HIV-1 reservoir in humans, knowledge of the effect of anti-retroviral drugs on macrophage-tropic HIV-1 isolates may help in the design of a strategy for prolonged suppression of viral replication. In-vitro selection and drug susceptibility testing of macrophage-tropic HIV-1 variants with reduced sensitivity to two non-nucleoside reverse transcriptase inhibitors, atevirdine and delavirdine (both bis-heteroarylpiperazines), is described here. The atevirdine-resistant isolate was cross-resistant to delavirdine, and the delavirdine-resistant isolate was cross-resistant to atevirdine. Interestingly, the atevirdine-resistant isolate, but not the delavirdine-resistant isolate, was also cross-resistant to nevirapin while the inhibition of viral replication of both isolates in macrophages by zidovudine was the same as that in the parental HIV-1 strain. Nucleotide sequence analysis of the resistant macrophage-tropic HIV-1 isolates showed that the atevirdine-induced resistance was due to a single amino acid change at codon 106 and that the delavirdine-induced resistance could be attributed to an amino acid change at codon 236. This study demonstrates that monocyte-derived macrophages can be used to investigate the phenotypic and genotypic acquisition of anti-retroviral drug resistance of macrophage-tropic HIV-1.