AEGiS-14IAC: Preferential in-utero transmission of HIV-1 subtype C compared to subtype A or D.

14th International AIDS Conference

Barcelona, Spain - July 7-12, 2002

Preferential in-utero transmission of HIV-1 subtype C compared to subtype A or D.

Int Conf AIDS 2002 Jul 7-12; 14:(abstract no. ThOrD1426)

Renjifo B, Vitamin and HIV Study Group TZ, Gilbert P, Chaplin B, Msamanga G, Mwakagile D, Fawzi W, Essex M
Harvard AIDS Institute, Boston, United States Territory

BACKGROUND: HIV-1 subtype C has become the most prevalent subtype in the HIV pandemic, accounting for the majority of all circulating subtypes in the world and the most devastating epidemics in Sub-Saharan Africa. In a large mother to child transmission (MTCT) cohort in Tanzania, we described that mothers infected with subtype C transmitted HIV-1 to their infants significantly more frequently than other subtypes. Since in-utero, intra-partum or breastfeeding represent different stages for MTCT, we sought to establish whether transmission during these periods was similar among subtypes, as such information might be useful for scheduling prophylaxis interventions.

METHODS: Infants were tested by PCR at birth, six weeks and at subsequent three month intervals until 18 months of age and thereafter until interruption of breastfeeding. C2-C5 envelope sequences were used for subtype classification.. Kruskal-Wallis and exact matched conditional logistic regression analysis (MLR) were used to assess differences in transmission among subtypes.

RESULTS: Of 253 infants positive for HIV-1, 101 infections were caused by subtype A, 73 by subtype C, 53 by subtype D, 22 by recombinants and 4 samples could not be typed. The distribution of infections during in-utero, intra-partum or breastfeeding periods was different among infants infected with subtype A, C, or D (p=0.032). Subtype C infections occurred earlier with a larger component of in-utero infections, while subtype D infections showed a larger fraction of breastfeeding infections (OR:3.8; 95% CI.1.33-10.8). This association was independent of maternal CD4 counts.

CONCLUSION: In comparison of subtypes A and D, a significant number of MTCT subtype C infections took place in-utero. Prophylaxis initiated at delivery may be less effective in protecting infants born in geographical regions with expanding subtype C epidemics.

Keywords: AEGIS, HIV-1, Tanzania, HIV Infections, CD4 Lymphocyte Count, HIV Seropositivity, Polymerase Chain Reaction, Case-Control Studies, Africa South of the Sahara, Child, Human, Infant, transmission

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ThOrD1426