HIV-1 LTR subtype and perinatal transmission

Multiple subtypes of HIV-1 have been identified; however, there is little d ata on the relative transmissibility of viruses belonging to different subt ypes. A matched case-control study addressed whether viruses with different long terminal repeat (LTR) subtypes were transmitted equally from mother t o infant. The LTR subtype was determined for 45 matched cases and controls who participated in a clinical trial in Tanzania. HIV-1 subtypes A, C, and D and intersubtype recombinant sequences were identified. Exact matched log istic regression analysis showed that viruses containing subtype A or inter subtype recombinant LTRs were 3.2 and 4.8 times more likely to be transmitt ed from mother to infant than viruses with subtype D LTRs. Viruses containi ng subtype C LTRs were 6.1 times more likely to be transmitted than those w ith subtype D LTRs. These differences in transmission were independent of m aternal CD4 at enrollment. Thus, it appears that HIV-1 subtype may be assoc iated with differing rates of perinatal transmission in Tanzania. (C) 2001 Academic Press.