TRANSMISSION FROM ONE CHILD TO ANOTHER OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 WITH A ZIDOVUDINE-RESISTANCE MUTATION

Background and Methods. We describe a child who apparently acquired hu man immunodeficiency virus type 1 (HIV-1) infection in the home settin g. The suspected source of infection was a child with the acquired imm unodeficiency syndrome who had received zidovudine and whose virus con tained a mutation associated with in vitro zidovudine resistance. The children were born to different HIV-1-infected mothers, but they lived in the same home between the ages of two and five years. Child 1 was infected perinatally; Child 2 was not and was repeatedly found to be s eronegative. Child 2 was examined because of acute lymphadenopathy and had seroconverted to HIV-1 positivity. HIV-1 proviral DNA was amplifi ed from peripheral-blood mononuclear cells and subjected to sequence a nalysis. Sequences from Child 2 were compared with those from Child 2' s mother, Child 1, and local HIV-1-infected control children. Results. HIV-1 nucleotide sequences from the third hypervariable region (V3) o f the env gene from Child 2 were much more similar to those of Child 1 (with a difference of 1.3 percent) than to those of Child 2's mother (a difference of 9.9 percent) or those of four local, epidemiologicall y unrelated children (differences of 10.1 to 16.3 percent). A zidovudi ne-resistance mutation at codon 215 of the reverse transcriptase gene (Thr-->Tyr) was found in Children 1 and 2, but not in Child 2's mother . Although the children had no documented exposure to each other's blo od, there had been numerous opportunities, including nosebleeds, bleed ing gums, and a laceration in Child 1. Conclusions. In the case we des cribe, HIV-1 with a mutation associated with zidovudine resistance was transmitted from one young child to another, apparently in the home a nd probably through unrecognized exposure to blood.