An autochthonous case of hepatitis C virus genotype 5a in Brazil: phylogenetic analysis

Identification and full-length molecular characterization of rare hepatitis C virus genotype 5a from India

This report presents a molecular characterization of the complete genome of a rare hepatitis C virus (HCV) genotype (GT5a) from India. Sequence homology of full genome revealed that the strain belonged to HCV GT5a. To trace the origin of this virus and to understand its evolutionary pattern, a phylogenetic reconstruction was carried out on full HCV genome sequences using Bayesian coalescent methods. The phylogenetic tree reconstruction revealed genotypic divergence, with formation of distinct clades. This analysis revealed that HCV genotype 5 might have originated from HCV genotype 3, as they have a recent common ancestor.

Genetic diversity of HCV in Brazil

BACKGROUND

Many studies have documented the molecular epidemiological scenario of HCV within individual Brazilian states, but we still have an incomplete understanding of the dispersion dynamics of the virus in different regions throughout the country.

METHODS

A total of 676 HCV NS5B gene sequences of subtypes 1a (n=321), 1b (n=170) and 3a (n=185), isolated from seven different Brazilian states covering four out of five regions were analysed in the present study. We also analysed 22 HCV NS5B gene sequences of minor genetic variants including genotype 2 (n=13), genotype 4 (n=6) and subtype 5a (n=3). Brazilian HCV sequences were aligned with sequences of non-Brazilian origin and subjected to maximum likelihood phylogenetic analyses.

RESULTS

These analyses revealed that the Brazilian HCV epidemic resulted from multiple introductions and autochthonous transmission of subtypes 1a, 1b, 3a and genotypes 2, 4 and 5. Brazilian HCV subtype 1a epidemic is dominated by the dissemination of one major clade; while Brazilian HCV subtypes 1b and 3a epidemics are characterized by concurrent dissemination of several independent HCV lineages. Some HCV Brazilian lineages of subtypes 1a, 1b, 2b and 3a were successful in becoming established and disseminated through several regions in the country. Despite significant phylogenetic intermixing of Brazilian sequences, the distribution of HCV strains from different states across lineages was not completely homogeneous.

CONCLUSIONS

These results demonstrate the existence of multiple introductions and local propagation of both prevalent and uncommon HCV genetic variants in Brazil and identify some major Brazilian HCV clades with nationwide dissemination. This study also suggests that the observed HCV diversity in Brazil has been shaped by both frequent viral migration among regions and in situ viral dissemination.