Emergence of an HIV-1 cluster harbouring the major protease L90M mutation among treatment-naïve patients in Tel Aviv, Israel.

OBJECTIVE

Drug resistance-associated mutations (DRMs) among HIV-1 treatment-naïve patients have increased in recent years. Their incidence and prevalence in various exposure risk categories (ERCs) were evaluated.

DESIGN

Plasma samples of HIV-1 treatment-naïve patients diagnosed between 2001 and 2009 at the Tel Aviv Medical Center were screened for DRMs.

METHODS

Samples obtained from patients following the HIV diagnosis were analysed retrospectively. Genotyping was carried out using the Trugene HIV-1 genotype kit (Siemens, Berkeley, CA, USA). Phylogenetic relationships among viral sequences were estimated using the maximum likelihood method.

RESULTS

Thirty-eight of the 266 analysed sequences (14.3%) had DRMs, all occurring exclusively in the group of men who have sex with men (MSM). The rate of DRMs has constantly risen, reaching a peak of 21.9% in 2009. Notably, protease inhibitor (PI) DRMs became the most frequent DRMs in 2009. Phylogenetic analysis showed a tight cluster comprising 13 of 14 viruses harbouring the L90M major PI resistance mutation, suggesting a single infection source.

CONCLUSION

There was an unexpectedly high rate of the major L90M PI resistance mutation in the MSM group. The clustered transmission of this mutation might be related to a high-risk sexual behaviour. Added to nonnucleoside reverse transcriptase inhibitor and nucleoside reverse transcriptase inhibitor resistance mutations, such a PI mutation may limit future therapeutic options for this particular patient population.