Background:  The efficacy of ART to prevent mother-to-child transmission (MTCT) has been widely proven. Since 1993, Argentina has had the AIDS National Law that protects and guaranties universal and free ART to every HIV-infected person. In spite of this, in Argentina, as in many other under-developed countries, many children every year are infected vertically. HIV treatment failure can have a variety of causes, including limited drug potency, poor adherence to regimens, and variations in drug metabolism. Yet, one of the most important factors associated with treatment failure is the transmission of viral strains resistant to ART. The aim of our study was to evaluate the presence of HIV variants susceptible or resistant to ART in children with recent HIV diagnosis.

Methods:  We evaluated 41 recently diagnosed HIV-infected children (born to HIV-infected mothers). Patients were recruited from December 2004 until September 2005. Genotypic sequencing of pol gene, with further Stanford University drug-resistance analysis, was performed. Plasma viral load and T lymphocytes count were also measured.

Results:  Of 41 children, 4 (9.75%) had viral strains with at least 1 mutation associated with ART resistance. These were:  L74V, K103N, V108I, Y181C, M184V, G190A, M46I, V118I, and T215I, conferring resistance to almost all nucleoside reverse transcription inhibitors (NRTI) and non-NRTI (NNRTI—didanosine, dideoxycytidine, abacavir, nevirapine, delavairdine, efavirenz, lamivudine, emtricitabine, zidovudine) and indinavir. Median viral load was 5.7 log_10, (range 3.34 to >5.7 copies/mL) and CD4 T lymphocytes median percentage was 16.0% (range 1 to 49%).

Conclusions:  A high percentage of children who have been infected with virus that have mutations associated to ART resistance were found among the population studied. This will certainly have serious implications in their progression to AIDS, as it may reduce the choice of active antiretroviral drugs. These results demonstrate that in developing countries, such as Argentina, where HIV MTCT is frequent, monitoring of drug resistance in children prior to treatment should be mandatory.