RESUMEN
Studies of the genetic heterogeneity of human T-cell lymphotropic virus type II (HTLV-II) have revealed the presence of two genetic subtypes, termed HTLV-IIa and HTLV-IIb. The HTLV-IIb subtype encodes an immunodominant epitope present at the C-terminus of the extended Tax protein and, by using an LTR-based, restriction fragment-length polymorphism (RFLP) assay, can be further classified into IIb60-IIb5, with HTLV-IIb1 (Central Amerindian-like) and HTLV-IIb5 (North Amerindian-like) being characteristic subtypes for Native American Indians. To determine the antigenic and genetic heterogeneity among HTLV-II-infected South Amerindians, we used a Tax synthetic peptide immunoassay on serum, and RFLP and phylogenetic analysis on LTR sequences amplified from genomic DNA from four Wayuu Indians of Colombia. The Wayuu specimens displayed seroreactivity to the immunodominant epitope located in the extended Tax region, as predicted, and demonstrated genetic heterogeneity by the presence of both the IIB1 (Wyu1, Zuc31) and IIb5 (Wyu2, Zuc42) subtypes sequences within separate phylogroups represented by the Guaymi Indian (IIb1) and North Amerindian (IIb5) sequences, respectively. Sequence analysis showed that major LTR regulatory motifs and the cis-acting repressive elements in the LTR RNA secondary structure were relatively conserved in both Wayuu subtypes, but the predicted secondary structure of the rex response stem loop in the Wyu2 (IIb5) LTR sequence was 45 nucleotides (nt) and 95 nt longer than that observed in the Wyu1 (IIb1) and G12.1 (IIb1) LTR sequences, respectively. These results extend our knowledge of the genetic heterogeneity of HTLV-II in South Amerindians.
Asunto(s)
Virus Linfotrópico T Tipo 2 Humano/clasificación , Indígenas Sudamericanos , Secuencia de Aminoácidos , Antígenos Virales/inmunología , Secuencia de Bases , Línea Celular Transformada , Colombia/epidemiología , ADN Viral/química , ADN Viral/genética , Productos del Gen tax/genética , Genes Virales , Heterogeneidad Genética , Infecciones por HTLV-II/epidemiología , Infecciones por HTLV-II/virología , Virus Linfotrópico T Tipo 2 Humano/genética , Virus Linfotrópico T Tipo 2 Humano/inmunología , Virus Linfotrópico T Tipo 2 Humano/aislamiento & purificación , Humanos , Datos de Secuencia Molecular , Conformación de Ácido Nucleico , Filogenia , Secuencias Repetitivas de Ácidos Nucleicos , SerotipificaciónRESUMEN
Analysis of sera from hospitalized Brazilian patients by whole-virus lysate-based enzyme immunoassay and Western blot indicated that 0.4% were reactive to HIV-2 alone while 4% were reactive to both HIV-1 and HIV-2. When these sera were tested for HIV antibody by type-specific peptide enzyme immunoassays, dual seropositivity was confirmed in only 0.4% of patients. To define genetically the HIV strains within the population, we analyzed peripheral blood mononuclear cells from selected seropositive patients for the presence of HIV-1 and HIV-2 proviral DNA using the polymerase chain reaction (PCR). Independent primers/probes sets were used for the amplification and detection of viral sequences from the long terminal repeat (LTR), gag, and protease (prt) gene regions. Our findings confirmed the serologic evidence of HIV-2 in Brazil and determined the extent of mixed HIV-1 and HIV-2 infections. Detailed evaluation of the amplified viral protease sequences by endonuclease restriction analysis and DNA sequencing independently confirmed mixed HIV-1 and HIV-2 infections in the two patients seropositive for HIV-1 and HIV-2. The data further indicated that these isolates are distinct from the HIV laboratory standards. We interpret the combination of culture and PCR findings to demonstrate the presence of both HIV-1 and HIV-2 in Brazil.