Diversity of group A rotavirus genes detected in the Triângulo Mineiro region, Minas Gerais, Brazil

Abstract

Group A rotaviruses are the main causative agent of infantile gastroenteritis. The segmented nature of the viral genome allows reassortment of genome segments, which can generate genetic variants. In this study, we characterized the diversity of the VP7, VP4 (VP8*), VP6, NSP4, and NSP5 genes of the rotaviruses that circulated from 2005 to 2011 in the Triângulo Mineiro (TM) region of Brazil. Samples with genotypes G2 (sublineages IVa-1 and IVa-3), G1 (sublineage I-A), G9 (lineage III), G12 (lineages II and III), G8 (lineage II), G3 (lineage III), P[4] (sublineages IVa and IVb), P[8] (sublineages P[8]-3.6, P[8]-3.3, and P[8]-3.1), I2 (lineage VII), E2 (lineages VI, XII, and X), and H2 (lineage III) were identified. The associations found in the samples were G1, G9, or G12 with P[8]-I1-E1-H1; G2 or G8 with P[4]-I2-E2-H2; G12 with I3-E3-H6; and G3 with P[4]-I2-E3-H3 (previously unreported combination). Reassortment events in G2P[4] strains and an apparent pattern of temporal segregation within the lineages were observed. Five TM samples contained genes that exhibited high nucleotide and amino acid identities with strains of animal origin. The present study includes a period of pre- and post-introduction of rotavirus vaccination in all Brazilian territories, thereby serving as a basis for monitoring changes in the genetic constitution of rotaviruses. The results also contribute to the understanding of the diversity and evolution of rotaviruses in a global context.

Keywords: Genetic variation; Genotype; Infantile diarrhea; Rotavirus.

Fig. 1

Maximum-likelihood phylogenetic analysis based on the VP7 (a), VP8* (b), VP6 (c), NSP4 (d), and NSP5 (e) gene nucleotide sequences of Triângulo Mineiro (TM) strains and the sequences from the GenBank database. The numbers at the nodes indicate bootstrap values (1000 replicates), and only values above 70% are shown. The trees are drawn to scale, with the branch lengths measured as the number of substitutions per site. The TM samples are marked with a solid circle, and the reference strains of each lineage and sublineage are marked with an open triangle. The uppercase letters followed by Arabic numerals, Roman numeral, and lowercase letters represent different genotypes, lineages, and sublineages, respectively, except for lineages and sublineages of the P[8] genotype, which are indicated by Arabic numerals, and sublineages of G1 strains, which are indicated by uppercase letters.

Fig. 1

Maximum-likelihood phylogenetic analysis based on the VP7 (a), VP8* (b), VP6 (c), NSP4 (d), and NSP5 (e) gene nucleotide sequences of Triângulo Mineiro (TM) strains and the sequences from the GenBank database. The numbers at the nodes indicate bootstrap values (1000 replicates), and only values above 70% are shown. The trees are drawn to scale, with the branch lengths measured as the number of substitutions per site. The TM samples are marked with a solid circle, and the reference strains of each lineage and sublineage are marked with an open triangle. The uppercase letters followed by Arabic numerals, Roman numeral, and lowercase letters represent different genotypes, lineages, and sublineages, respectively, except for lineages and sublineages of the P[8] genotype, which are indicated by Arabic numerals, and sublineages of G1 strains, which are indicated by uppercase letters.

Fig. 1

Maximum-likelihood phylogenetic analysis based on the VP7 (a), VP8* (b), VP6 (c), NSP4 (d), and NSP5 (e) gene nucleotide sequences of Triângulo Mineiro (TM) strains and the sequences from the GenBank database. The numbers at the nodes indicate bootstrap values (1000 replicates), and only values above 70% are shown. The trees are drawn to scale, with the branch lengths measured as the number of substitutions per site. The TM samples are marked with a solid circle, and the reference strains of each lineage and sublineage are marked with an open triangle. The uppercase letters followed by Arabic numerals, Roman numeral, and lowercase letters represent different genotypes, lineages, and sublineages, respectively, except for lineages and sublineages of the P[8] genotype, which are indicated by Arabic numerals, and sublineages of G1 strains, which are indicated by uppercase letters.