Resistance-associated mutations to etravirine (TMC-125) in antiretroviral-naïve patients infected with non-B HIV-1 subtypes.

Susceptibility to etravirine (ETR), an expanded-spectrum nonnucleoside reverse transcriptase inhibitor (NNRTI), is dependent on the type and number of NNRTI resistance-associated mutations (RAMs). Studies have shown that some HIV-1 subtypes may have natural polymorphisms described as ETR RAMs. This study addresses the prevalence of ETR RAMs in treatment-naïve patients infected with HIV-1 non-B subtypes and its potential impact on ETR susceptibility. The prevalence of ETR RAMs in 726 antiretroviral-naïve patients infected with non-B HIV-1 subtypes was studied. ETR genotypic resistance was interpreted according to Agence Nationale de Recherches sur le SIDA and Stanford algorithms. NNRTI phenotypic susceptibilities of samples with at least one ETR RAM were measured. Overall, 75 (10.3%) of 726 sequences harbored at least one ETR RAM: sequences from 72 patients (10%) each had one ETR RAM, and sequences from 3 patients (0.4%) each had two ETR RAMs (V90I and Y181C in one case and V90I and A98G in two cases). None of the viruses had three or more ETR RAMs, and none were consequently classified as resistant to ETR. All sequences with two ETR RAMs belonged to subtype CRF02_AG. The presence of one ETR RAM was statistically more frequent in subtype CRF02_AG than in other non-B subtypes (P=0.004). Three new mutation profiles (E138A and V179I, Y181C and H221Y, and V90I and Y181C) showing decreased ETR phenotypic susceptibility were identified. In conclusion, although the prevalence of ETR RAMs in treatment-naïve patients infected with non-B HIV-1 subtypes was 10%, in most cases this had no significant impact on ETR susceptibility. However, the transmission of drug-resistant viruses with Y181C in a non-B genetic background has a potential for impact on ETR susceptibility.

Genetic barriers for integrase inhibitor drug resistance in HIV type-1 B and CRF02_AG subtypes.

BACKGROUND: HIV type-1 (HIV-1) integrase (IN) inhibitor resistance is the consequence of mutations that are selected in the viral IN gene targeted by antiretroviral drugs, such as raltegravir (RAL) and elvitegravir (EVG). The genetic barrier, defined as the number of viral mutations required to overcome the drug-selective pressure, is one of the important factors in the development of drug resistance. The genetic barrier for IN inhibitor resistance was compared between HIV-1 subtype B and HIV-1 subtype CRF02_AG, which is highly prevalent in West Africa and becoming more frequent in developed countries. METHODS: IN nucleotide sequences from 73 HIV-1 subtype B and 77 HIV-1 subtype CRF02_AG antiretroviral-naive patients were examined at 19 IN amino acid positions implicated in RAL and EVG resistance. RESULTS: The majority (14/19) of the studied positions showed a high degree of conservation of the predominant codon sequences leading to a similar genetic barrier between subtypes B and CRF02_AG. Nevertheless, at positions 140 and 151, the variability between subtypes affected the genetic barrier for the mutations G140C, G140S and V1511 with a higher genetic barrier being calculated for subtype CRF02_AG. CONCLUSIONS: The major IN mutations E92Q, Q148K/R/H, N155H and E157Q (implicated in the resistance of IN inhibitors RAL and EVG) are highly conserved between subtypes B and CRF02_AG and display a similar genetic barrier. However, subtype CRFO2_AG showed a higher genetic barrier to acquire mutations 6140S, 6140C and V1511 as compared with subtype B, which could play a role in the resistance to RAL and/or EV6.

Evolution of genetic diversity and drug resistance mutations in HIV-1 among untreated patients from Mali between 2005 and 2006.

OBJECTIVES: To describe HIV-1 variants circulating in Mali and to estimate the rate of transmission of HIV-1 drug resistance in 2006. PATIENTS AND METHODS: Viral reverse transcriptase (RT) and protease (PR) genes from 198 antiretroviral (ARV)-naive patients diagnosed HIV-1 positive in May 2006 in Bamako and Segou were sequenced. RESULTS: Although CRF02_AG was always the predominant HIV-1 subtype observed (72%), a higher genetic diversity than that in 2005 was observed. The overall prevalence of primary resistance is 11.5% in Mali in 2006, according to the 2007 IAS-USA list of mutations [nucleoside RT inhibitor (NRTI): 1.5%, non-NRTI (NNRTI): 9% and PI: 1%], and 2.5% (NRTI: 1%, NNRTI: 1.5% and PI: 0%), according to the Stanford list of mutations. There was no significant difference between 2005 and 2006 in the overall primary resistance prevalence or in the prevalence of mutations in the different ARV classes. Resistance mutations found in RT and PR genes are in agreement with the highly active antiretroviral therapy regimen available in Mali, except for V90I, V106I and A98G mutations which are associated with etravirine resistance, but polymorphic in non-B subtypes. CONCLUSIONS: HIV-1 genetic diversity seems increased in Mali, but the overall HIV-1 primary resistance prevalence remains low. This is consistent with the findings from other West African countries where prevalence rates are lower than 5%. However, considering the large scaling up of ARV use in this country, it is necessary to regularly monitor the development of primary resistance in Mali.

Genetic diversity and drug resistance mutations in HIV type 1 from untreated patients in Bamako, Mali.

OBJECTIVE: To determine the genetic diversity of HIV-1 reverse transcriptase (RT) and protease sequences and the presence of mutations linked to antiretroviral (ARV) resistance in treatment-naive, HIV-1-infected individuals living in Mali. METHODS: Ninety-eight samples from ARV drug-naive, HIV-1-infected patients were collected in one clinical centre in Bamako, Mali in 2005. RT and protease genes were sequenced in order to perform phylogenetic and resistance analyses. RESULTS: The most prevalent subtype was CRF02-AG (75% of cases), followed by the CRF06-cpx subtype (20%). Intersubtype recombinants between CRF02-AG, CRF01-AE and CRF06-cpx were also described in 5% of cases. After 4 years of ARV use in Mali, two previously untreated individuals (2%; 95% CI: 0.00-4.77%) were found to have resistant viruses, one with a single nucleoside mutation and one with K103N non-nucleoside reverse transcriptase inhibitor resistance mutation. No evidence of transmitted protease inhibitor resistance mutations was found. CONCLUSION: These data provide direct evidence for the circulation of HIV-1 isolates containing resistance mutations in treatment-naive patients in Mali. Since ARV use in Mali began, more than 5000 patients have started treatment, mostly with Triomune (stavudine/lamivudine/nevirapine). The resistance-associated mutations detected in the present study are consistent with this treatment regimen. Continued surveillance will be required to monitor the emergence of ARV resistance in this country.