Rotavírus (RV) is the principal viral agent associated with gastroenterites, being
responsible for 39% of the diarrhea cases that need hospitalization and with 520.000
deaths among children under five years. It belongs the to Reoviridae family, genus
Rotavirus, the genome consists of 11 segments of double-stranded RNA that
encoding 12 proteins, six structural (VPs) and six non-structural (NSPs). The VP4
protein, together VP7 protein, compose the outer layer of the RV, defining genotypes
P and G, respectively. Until now, at least 23 different G genotypes and 31 P
genotypes have been established. The G9 genotype emerged in world scale, and is
possibly associated with severe clinical manifestation, being generally associated
with P[8] genotype. The G9 genotype has 6 distinct lineages and P[8] 4 lineages. The
aimed of this study was the characterization of VP4 and VP7 genes of the RV G9
genotype, that circulated in the metropolitan region of Belém, in the period of 1999 to
2007. The viral dsRNA of 38 selected samples were extracted from fecal
suspensions and submitted to electrophorese in gel of poliacrylamide to determine
the electropherotypes, followed sequencing reaction. In the present investigation,
was possible analyzed 32 selected samples, all of them G9P[8] genotype, with long
electropherotype. Phylogenetic analysis of VP7 gene showed that all G9 strains
belong to lineage 3 with high similarity indexes, with 8 nucleotide changes. However,
only three amino acids changes were observed in the positions 43 (I→V), 66 (A→V)
e 73 (Q→R), being the substitutions at positions 43 and 73 exclusive of the samples
isolated in 2007 year. Phylogenetic analysis of VP4 gene revealed that all strains
P[8] belong to lineage 3, with 15 nucleotide changes, that showed four amino acids
substitutions at positions 108 (V→I), 172 (R→K), 173 (I→V) e 275 (K→R). The amino
acids substitutions at positions 172 and 275 were exclusive of the strains isolated
from 1999 to 2002. The samples of the present study showed high homology
throughout the studied period. The strains isolated in 2007 were the most divergence
either to VP4 as to VP7 gene. It is important the continuous surveillance of G9
genotype in the metropolitan region of Belém, to detected possible new genetic
variants that can represent a challenge to the current strategies of immunization.
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