Low incidence of nevirapine resistance seen in Cameroon women given drug for MTCT

Michael Carter
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This article is more than 21 years old.

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.

Glossary

subtype

In HIV, different strains which can be grouped according to their genes. HIV-1 is classified into three ‘groups,’ M, N, and O. Most HIV-1 is in group M which is further divided into subtypes, A, B, C and D etc. Subtype B is most common in Europe and North America, whilst A, C and D are most important worldwide.

sample

Studies aim to give information that will be applicable to a large group of people (e.g. adults with diagnosed HIV in the UK). Because it is impractical to conduct a study with such a large group, only a sub-group (a sample) takes part in a study. This isn’t a problem as long as the characteristics of the sample are similar to those of the wider group (e.g. in terms of age, gender, CD4 count and years since diagnosis).

vertical transmission

Transmission of an infection from mother-to-baby, during pregnancy, childbirth, or breastfeeding.

 

statistical significance

Statistical tests are used to judge whether the results of a study could be due to chance and would not be confirmed if the study was repeated. If result is probably not due to chance, the results are ‘statistically significant’. 

pathogenesis

The origin and step-by-step development of disease.

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.

References

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.

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