Molecular characterization of novel G5 bovine rotavirus strains

Abstract

Group A rotaviruses are a major cause of acute gastroenteritis in young children as well as many domestic animals. The rotavirus genome is composed of 11 segments of double-stranded RNA and can undergo genetic reassortment during mixed infections, leading to progeny viruses with novel or atypical phenotypes. The aim of this study was to determine if the bovine group A rotavirus strains KJ44 and KJ75, isolated from clinically infected calves, share genetic features with viruses obtained from heterologous species. All 11 genes sequences of the KJ44 and KJ75 strains were sequenced and analyzed. The KJ44 VP4 had 91.7% to 96.3% deduced amino acid identity to the bovine related P[1] strain, whereas the KJ75 strain was most closely related to the bovine related P[5] strain (91.9% to 96.9% amino acid identity). Both KJ44 and KJ75 strains also contained the bovine related VP3 gene. The remaining 9 segments were closely related to porcine group A rotaviruses. The KJ44 and KJ75 strains showed high amino acid identity to the G5 rotaviruses, sharing 90.4% to 99.0% identity. In addition, these strains belonged to the NSP4 genotype B, which is typical of porcine rotaviruses and subgroup I, with the closest relationship to the porcine JL-94 strain. These results strongly suggest that bovine rotavirus strains with the G5 genotype occur in nature as a novel G genotype in cattle as a result of a natural reassortment between bovine and porcine strains.

FIG. 1.

Phylogenetic tree of the VP7 protein of the KJ44 and KJ75 strains indicating its genetic relationship with other G genotypes.

FIG. 2.

Comparison of the deduced amino acid sequence of the VP7 protein of the KJ44 and KJ75 strains with that of selected rotavirus strains that are representative of each G genotype identified. The highly conserved proline (•), cysteine (▪), and deduced glycosylation (▾) sites are indicated. The hydrophilic (solid horizontal bar) and hydrophobic (dashed horizontal bar) regions are noted. The variable regions (VRs) are indicated by brackets above the sequences.

FIG. 3.

Phylogenetic tree of the VP4 protein of the KJ44 and KJ75 strains indicating its genetic relationship with other P genotypes.

FIG. 4.

Phylogenetic trees of the VP6 protein (A) and NSP4 protein (B) of the KJ44 and KJ75 strains indicating their genetic relationship with other selected group A rotavirus strains.

FIG. 5.

Phylogenetic trees of the VP1 protein (A), VP2 protein (B), and VP3 protein (C) of the KJ44 and KJ75 strains indicating their genetic relationship with other selected group A rotavirus strains.

FIG. 6.

Phylogenetic trees of the NSP1 protein (A) and NSP2 protein (B) of the KJ44 and KJ75 strains indicating their genetic relationship with other selected group A rotavirus strains.

FIG. 7.

Phylogenetic trees of the NSP3 protein (A) and NSP5 protein (B) of the KJ44 and KJ75 strains indicating their genetic relationship with other selected group A rotavirus strains.