A single dose of nevirapine to prevent mother to baby transmission of HIV is associated with a low incidence of NNRTI resistance, according to a small study conducted in the Cameroon and presented to the Second International AIDS Society Conference on HIV Pathogenesis and Treatment in Paris on July 15th.
Investigators also found that approximately 20% of HAART-treated patients had major mutations conferring resistance to at least one class of antiretroviral drugs, supporting the need for the urgent introduction of HIV treatment guidelines.
The study, conducted by the Hopital de Jour in the Cameroon, involved 35 women who were provided with a single dose of nevirapine to prevent mother to baby transmission of HIV, and 93 HAART-treated patients. Investigators wished to establish the incidence of major HIV resistance mutations and the diversity of HIV subtypes in their patients.
Blood samples were obtained from the nevirapine-treated women six weeks after they had received their dose of the NNRTI. Only one woman (2.8%) had mutations consistent with resistance to nevirapine. This is considerably lower than rates of NNRTI resistance observed in other African countries where a single dose of nevirapine is used to prevent vertical transmission of HIV, and may reflect the timing of the sample, long after the withdrawal of drug pressure.
Among the HAART-treated patients, 19 (20.4%) individuals had resistance to at least one class of antiretroviral drugs. Resistance to nevirapine was observed in eight patients, with four of these also being resistant to 3TC. One patient had major resistance mutations associated with high-level resistance to all three classes of antiretroviral drugs.
The only factor associated with an increased risk of resistance was length of treatment with antiretroviral therapy, with resistant patients treated for an average of ten months, compared to seven months treatment in non-resistant patients. This difference was statistically significant (p
HIV subtype tests were performed on 34 patients, revealing a high diversity of subtypes. The most prevalent subtype was CRF02, which was present in 64.7% of individuals, 8.8% had subtype D, subtypes O, A, F2, and CRF02/F were each present in 5.9% of patients. Investigators stressed that all the patients in their study had non-B subtype and that natural mutations in various non-B subtypes are associated with a poor response to HAART.
The presenting investigator said further studies were underway to assess the level of NNRTI resistance in mothers treated with a single dose of nevirapine. He also called for the HIV treatment and monitoring guidelines to be introduced in Cameroon and other African countries.
Kouanfack C et al. HIV-1 genotypic resistance to antiretroviral treatment in Cameroon, in populations treated by HAART and by single-dose nevirapine to prevent MTCT. Antiretroviral Therapy 8 (suppl.1), abstract 163, 224, 2003.