VERTICAL TRANSMISSION OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 IN JAPAN, 1989-1997 - PRESENCE OF 2 SUBTYPES SUBTYPE-B AND SUBTYPE-E WITH SUBTYPE-E PREDOMINANCE

A collaborative group for studying vertical transmission of human immu nodeficiency virus (HIV)-1 in pregnant women and their babies was esta blished in Japan in 1989. Forty-two infants, including 13 HIV-1-infect ed, 25 uninfected and four of undetermined status and 15 control child ren born to HIV-1 negative mothers were diagnosed and followed from bi rth to 1.5 years. All strains from HN-positive infants were either cla de E (eight infants, 61.5%) or B (five infants, 38.5%) according, to D NA sequencing specific for the HIV-1 C2-V3 region. The 42 mothers with HIV-1 were women with sexual-risk behavior ii-om all regions, but wer e concentrated in the Kanto District. In this group of HIV-infected ch ildren, there was no significant difference between the transmissibili ty of their mother's clade E and B viruses. Eight (61.5%) of the 13 vi rus-infected babies were Japanese and five (62.5%) of the eight were p ositive for HIV-1 clade E. The V3 loop region of the clade E virus of the babies was conserved but approximately 60% of the sequences which showed a substitution of aspartic acid by asparagine at position 29. T he results suggest that HIV-1 clade E may be predominant in vertical t ransmissions and are phenotypically different from HIV-1 in persons wi th various other risk behaviors in Japan.