title: Potential impact of viral load and genetic makeup of HIV type 1 on mother-to-child transmission: characterization of env-C2V3C3 and nef sequences.
abstract: HIV-1 mother-to-child transmission (MTCT) was evaluated in terms of the molecular characterization of the env and nef genomic regions and quantification of maternal RNA viral loads. Assignment of viral subtype was achieved by direct sequencing of PCR 1172 products amplified from proviral DNA in 45 HIV-1-nontransmitting mothers (NTM), along with 13 pairs of HIV-1-transmitting mothers (TM) and their infected children (C). Analysis of the env C2V3C3 and nef sequences revealed that subtypes G and B, and their genetic combinations (AG, BG), accounted for over 84.5% of all viruses identified. The genetic structure form envA-nefG was the most commonly observed, with a lower frequency in the NTM (13.3%) compared to the TM (23.1%) group. A greater number of genetic forms was observed among NTM, namely the presence of sequences assigned to subtypes D and F, as well as the intergenetic A/J, and C/U, recombinant forms, along with a mosaic provirus with a complex putative envA-nefEGE genetic structure. No significant differences were found when RNA viral loads were evaluated as a function of the viral subtypes. Nevertheless, a relatively high quantification of HIV-1 RNA was obtained in the NTM group, emphasizing the importance of the compliance and effectiveness of therapeutic schemes to control viral replication and reduce the risk of HIV vertical transmission. V3 sequences displaying features associated with the R5 phenotype dominated in both groups. Both C2V3C3 and Nef's functional domains were conserved during HIV-1 vertical transmission.
authors.affiliation: Laboratório de Referência da SIDA, Instituto Nacional de Saúde, 1649-016 Lisboa, Portugal. elizabeth.padua@insa.min-saude.pt
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Pádua
authors.forename: Ricardo
authors.initials: R
authors.lastname: Parreira
authors.forename: Rita
authors.initials: R
authors.lastname: Tendeiro
authors.forename: Baltazar
authors.initials: B
authors.lastname: Nunes
authors.forename: João
authors.initials: J
authors.lastname: Castela
authors.forename: Isabel
authors.initials: I
authors.lastname: Soares
authors.forename: Ana
authors.initials: A
authors.lastname: Mouzinho
authors.forename: Eduarda
authors.initials: E
authors.lastname: Reis
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Paixão
mesh_terms: D000328:Adult; D002648:Child; D005260:Female; D014644:Genetic Variation; D015699:HIV Envelope Protein gp120 / Q000737:chemistry / Q000235:genetics; D015658:HIV Infections / Q000635:transmission* / Q000821:virology; D015497:HIV-1 / Q000145:classification / Q000235:genetics / Q000502:physiology; D006801:Humans; D018445:Infectious Disease Transmission, Vertical; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics; D012367:RNA, Viral / Q000097:blood; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA; D019562:Viral Load; D054299:env Gene Products, Human Immunodeficiency Virus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D054311:nef Gene Products, Human Immunodeficiency Virus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D015699:HIV Envelope Protein gp120; C059762:HIV envelope protein gp120 (305-321); D010446:Peptide Fragments; D012367:RNA, Viral; D054299:env Gene Products, Human Immunodeficiency Virus; D054311:nef Gene Products, Human Immunodeficiency Virus