Perfil epidemiológico, molecular e filogenético do vírus da hepatite B circulantes no Estado de Roraima

Abstract

The infection through Hepatitis B virus (HBV) is a serious global public health issue, presenting in Roraima high prevalence rates. It is parenterally and sexually transmitted primarily. Its genome consists of a circular and partially double-stranded DNA, with about 3.2 kb. HBV has a high degree of genetic diversity. HBV genotypes play an important role in the virus-host relationship. Mechanisms for the persistence of HBV infection involve several aspects, including immunogenic factors. The objective of the study was to perform the epidemiological characterization of HBV patients and genetics of circulating HBV strains from the partial sequencing of the S gene, allowing the detection of genotypes, possible changes in the genetic pattern of the strains and polymorphisms in a human gene (CCR5), relating to the clinical course, susceptibility or protection against infection. The study population consisted of patients with HBV and control subjects. Extraction of viral and genomic DNA was performed using commercial kits. The amplification of the S gene and polymorphism (CCR5 gene) was performed through the Polymerase Chain Reaction (PCR), using specific initiators. The positive fragments of the S gene were sequenced, genotyped and used in the phylogenetic study based on the Bayesian method. Most of the HBV patients were male (56.25%), aged between 31-50 years (54.29%). The brown race was prevalent in 45.31%, 29.68% had incomplete primary education, 44.53% were married and 66.40% were residents of the capital Boa Vista. Regarding the probable source/mechanism of infection, sexual transmission occurred in 26.97% of the cases. Vaccination was reported as ignored in 28.12% of those involved in the study, and among those who reported the information, the complete vaccination schedule represented 25%. Regarding the contact with HBV patients, 51.56% had no contact, and among those who had contact, 53.12% reported occupational contact. The detectable viral load <2000 IU/mL was found in 57.81% of patients, 51.13% were on treatment, and, among the drugs, the most frequent was Tenofovir, with 56.04%. Forty sequences were genotyped and the Maximum Clades Reliability (MCC) tree confirmed the presence of the A, D and F genotypes, with a prevalence for the A genotype (70%), p <0.0001. The sub genotypes found were A1, A2, D2, D3, D4, F2a and F3, the latter being detected for the first time in Brazil. As for the CCR5 gene, for the allelic and genotype frequencies of the analyzed groups, the HBV population was not in the Hardy-Weinberg equilibrium (p = 0.0139). No difference was observed in the frequency (2.6%) of the Δ32 allele between the groups (p = 0.9626). The frequency of the Δ32/Δ32 mutation was 0.53% in the HBV group and 0% in the control group. The study of HBV molecular diversity and epidemiology, in addition to the genetic standards of the general population, can contribute to a better understanding of the disease at a local level and allow the adoption of measures to prevent and control infection.