This study analyzed the genes pol and env to determine the genetic variability of HIV-1 in Central Brazil. Forty-one isolates of HIV-1-infected individuals had protease, reverse transcriptase, and C2C3/ env amplified by nested PCR and sequenced. The subtype was determined by the program REGA and phylogenetic analyses. The samples identified as putative recombinant forms were analyzed by SimPlot. A high prevalence of subtype B (95.1%) was observed, followed by mosaic viruses B/F (4.9%). The amino acid sequences from 30 HIV-1 isolates were analyzed for the antigenic intrasubtype diversity. The most prevalent gp120 V3 loop motif was the GPGR (United States/Europe) (43.3%), described in B and F subtypes, followed by the GPGK tetrapeptide (10%). The Brazilian variant B" (GWGR), GFGR, and GLGR tetrapeptides were found in 6.7%. Other V3 variants were found in eight isolates (26.7%). Phylogenetic tree analysis was also performed in order to verify the relationship of the HIV-1 samples from Central Brazil with other HIV-1 sequences that circulate in Brazil. The subtype B sequences from Central Brazil formed a polyphyletic cluster in the tree, indicating that these strains are similar to those from other geographic regions. These results contribute to the understanding of HIV in Brazil, and may prove useful for the development of vaccine candidates.
Some estimates indicate that several groups of viruses, including the Human papillomavirus are associated to 20% of all human cancers. Cervical cancer is the best example of how a viral infection may progress to cancer. The E2 gene is disrupted when the HPV genome integrates in the cellular DNA. This gene inhibits the expression of E6 and E7 genes. E6 protein leads to degradation of p53 (cellular suppressing tumour protein), while E7 binds to pRb (retinoblastoma susceptibility protein), which fails in negatively regulating the cell cycle (from G1 to S). Moreover, other viral protein, E5, seems to act sinergically with the epidermic growing factor. When expressed in many different systems, the L1 HPV protein is able to form icosahedral particles, VLPs, similar to viral capsids, but lacking the DNA genome. The discovery of this L1 property led to progresses in studies on HPV infection immunogenicity and to the perspective of developing vaccines against that virus. VLPs are highly immunogenic and when injected in rabbits may induce the production of high titers of specific antibodies. The choice of HPV types to be used for VLP production, still depends on describing the prevalence of genotypes in different non-symptomatic and symptomatic populations. Sorological surveys in women infected with HPV-16, indicates 50% to 60% soropositivety to antibodies against viral capsid proteins.
The present study on molecular characterization of a human papillomavirus (HPV) isolated in Central Brazil describes the L1 gene sequence from a new variant of HPV-58, the isolate Bsb-02. The sample was from a smear obtained from a woman with cervical intraepithelial neoplasia grade II. The whole L1 gene from isolate Bsb-02 was sequenced automatically, showing 99.1% nucleotide identity with the gene from the HPV-58 reference. The clustering between Bsb-02 and HPV-58 reference sequence was also supported by phylogenetic analysis. Fourteen nucleotide substitutions were observed: eight were synonymous and six were associated with amino acid substitutions. A10V and V144I have not been previously described. At GenBank, the only complete L1 sequence from HPV-58 in addition to the HPV-58 reference one is that of Bsb-02. These data provide information that may be relevant to HPV diagnosis and to rational vaccine strategies. HPV variants may also be associated with host immune responses and with the risk of cervical neoplasia.
Correspondence
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