FACING A NEW EPIDEMIC (?) MOLECULAR EPIDEMIOLOGY OF HIV AMONG MOTHER AND CHILD COHORT IN MONTREAL

N Lapointe, J Samson, M Boucher
Ste-Justine Hospital, Centre Maternel et Infantile sur le SIDA, University of Montreal, Montreal, Quebec

Objective: To document genetic differences in HIV among pregnant women as well as response to treatment during pregnancy and transmissibility of HIV to the newborn.
Method: During last 24 months, 74 HIV-infected pregnant women were recruited. HIV subtypes were identified by sequence analysis of polymerase region, generated for resistance testing, among 37 pregnant women who had a viral load (VL) >1000 copies/ml. VL was quantified using Chiron assay and CD4 cells by flowcytometry.
Results: HIV genotyping was unsuccessful in 4 women, due to poor sequencing quality. Clade B viruses were detected among 18/33 (54,5%) women and nonclade B viruses among 15/33 (45,5%). In the nonclade B viruses, 24% were of subtype A (A,AE,AG); 6% subtype C, 9% subtype D and 3% of each subtypes F and G. All women having nonclade B came from Africa: 6 from Congo-Zaire, 2 from Cameroon, 2 from Rwanda and one each from Burkina Faso, Burundi, Ivory Coast, Ghana and Eritrea. Before treatment, the mean VL among clade B and nonclade B subgroups was respectively 18 361 (±19 129) and 24 116 (±55 657) and CD4 cells were respectively 454 (±216) and 254 (±144). All pregnant women received antiretroviral therapy to reduce perinatal transmission. At delivery, the mean VL among clade B and nonclade B subgroups was respectively 527 (±866) and 1 280 (±3 432) and CD4 cells were respectively 658 (±382) and 421 (±194). All children (n=31) born to HIV-infected treated mothers are uninfected.
Conclusion: The diversity of HIV-subtypes is rapidly increasing in our population. A similar pattern of decrease of VL and increase of CD4 during treatment was observed in both subgroups. No association was found between clade diversity and HIV transmission to the newborn: reassuring for prophylaxis treatment in Africa.