Evidence for differences in the sexual transmission efficiency of HIV strains with distinct drug resistance genotypes.

BACKGROUND The transmission of drug-resistant human immunodeficiency virus type 1 (HIV-1) is a matter of major concern, because it could compromise the response to antiretroviral therapy. MATERIAL AND METHODS From 1997 through 2003, genotypic drug resistance profiles in 89 patients with recent HIV-1 seroconversion were compared in a case-control study with HIV-1 genotypes obtained from 520 subjects identified at Hospital Carlos III in Madrid, Spain, as "potential transmitters" of drug-resistant virus. This group consisted of HIV-infected patients experiencing virologic failure of antiretroviral therapy. RESULTS Drug resistance mutations were recognized in 15 (16.8%) of 89 patients with recent HIV-1 seroconversion (the seroconverter group), providing resistance to nucleoside reverse-transcriptase inhibitors (NRTIs) in 14.6%, nonnucleoside reverse-transcriptase inhibitors (NNRTIs) in 3.4%, and protease inhibitors (PIs) in 3.4%. Among individuals who were potential transmitters of HIV-1 (the potential transmitter group), drug resistance mutations were found in 80%, providing resistance to NRTIs in 73.7%, NNRTIs in 36.4%, and PIs in 38.7%. The estimated ratio of individuals with recent HIV-1 seroconversion to potential transmitters for drug-resistance genotypes was 0.23 for resistance to NRTIs, 0.09 for resistance to NNRTIs, and 0.09 for resistance to PIs. For specific resistance mutations, the ratio of individuals with recent HIV-1 seroconversion to potential transmitters was 0.18 for 41L, 0.20 for 215Y/F (including revertants), 0.06 for 184V, 0.04 for 103N, and 0.14 for 181C when considering drug resistance mutations in the reverse transcriptase (RT) gene; the ratio was 0.12 for 46L, 0.06 for 82A/T/S, and 0.08 for 90L, when examining PI resistance mutations. CONCLUSION Strains of HIV with some drug resistance genotypes (41L, 215Y/F, and 181C in the RT gene and 46L in the protease gene) may be more efficiently transmitted than strains with other drug resistance mutations (184V and 103N in the RT gene and 82A/S/T and 90M in the protease gene).