RESUMEN
Among the major circulating HIV-1 subtypes, subtype C is the most prevalent. To generate full-length subtype C clones and sequences, we selected 13 primary (PBMC-derived) isolates from Zambia, India, Tanzania, South Africa, Brazil, and China, which were identified as subtype C by partial sequence analysis. Near full-length viral genomes were amplified by using a long PCR technique, sequenced in their entirety, and phylogenetically analyzed. Amino acid sequence analysis revealed 10.2, 6.3, and 17.3% diversity in predicted Gag, Pol, and Env protein sequences. Ten of 13 viruses were nonmosaic subtype C genomes, while all three isolates from China represented B/C recombinants. One of them was composed primarily of subtype C sequences with three small subtype B portions in gag, pol, and nef genes. Two others exhibited these same mosaic regions, but contained two additional subtype B portions at the gag/pol overlap and in the accessory gene region, suggesting ongoing B/C recombination in China. All subtype C genomes contained a prematurely truncated second exon of rev, but other previously proposed subtype C signatures, including three potential NF-kappa B-binding sites in the viral promoter-enhancer regions, were found in only a subset of these genomes.
Asunto(s)
Genoma Viral , Infecciones por VIH/virología , VIH-1/genética , Adulto , Secuencia de Bases , Brasil , China , Femenino , Productos del Gen env , Productos del Gen gag/genética , Productos del Gen pol/genética , Productos del Gen rev , Duplicado del Terminal Largo de VIH/genética , VIH-1/clasificación , Humanos , India , Masculino , Persona de Mediana Edad , Datos de Secuencia Molecular , Filogenia , Alineación de Secuencia , Sudáfrica , Tanzanía , Productos del Gen rev del Virus de la Inmunodeficiencia HumanaRESUMEN
As part of the WHO Network for HIV Isolation and Characterization, we PCR amplified, cloned, and sequenced gp120 and gp160 genes from 12 HIV-1 isolates collected in four WHO-sponsored vaccine evaluation sites (Brazil, Rwanda, Thailand, Uganda). Envelope clones were derived from PBMC-grown isolates obtained from asymptomatic individuals within 2 years of seroconversion. Analysis of their deduced amino acid sequences identified all but one to contain an uninterrupted open reading frame. Transient expression and biological characterization of selected gp160 constructs identified six clones to encode full length and functional envelope glycoproteins. Phylogenetic analysis of their nucleotide sequences revealed that they represent HIV-1 subtypes A, B, C, and E. Since current knowledge of HIV-1 envelope immunobiology is almost exclusively derived from subtype B viruses, these reagents should facilitate future envelope structure, function and antigenicity studies on a broader spectrum of viruses. This should assist in the design and evaluation of effective vaccines against HIV-1.