Identification of G and P genotype-specific motifs in the predicted VP7 and VP4 amino acid sequences.

The research studied the genotypic qualities of L338, a unique equine rotavirus strain, and the evolutionary relationship it shares with other equine rotavirus strains. Upon analysis, the researchers suggest that this particular strain may be the result of an interspecies reassortant with other group A rotavirus strains.

Overview of the L338 Strain

• The L338 strain of equine rotavirus (ERV) was found to be a unique G13P[18] genotype – this meant it was different from other ERVs in terms of its genetic components.
• Its genotype constellations were confirmed as G13-P[18]-I6-R9-C9-M6-A6-N9-T12-E14-H11. These ‘constellations’ represent the different components of the strain’s genetic makeup.
• Of these genotype constellations, the L338 strain was only found to share its P[18] and I6 genotypes with other ERVs – its remaining 9 RNA segments were unique.

Evolutionary Relationship with Other ERVs

• The researchers found that the unique RNA segments of the L338 strain form unique phylogenetic lineages – these are evolutionary links that show the development of the strain over time.
• These lineages were found to be distinct from the cogent genes of all other group A rotavirus (RVA) strains – including other ERVs.
• However, the L338 strain did share conserved regions with other RVA strains, indicating a closer genomic relationship with these strains as opposed to other ERVs.
• This led to the suggestion that the L338 strain is not an endogenous equine RV, but rather, it may have evolved as an interspecies reassortant with other RVA strains. The term ‘reassortant’ means that the strain may have emerged due to the mixing or recombination of genes from different species.

Identification of Genotype-specific Motifs

• The researchers also identified genotype-specific motifs in the VP7 and VP4 amino acid sequences of the L338 strain. Motifs are recurring elements that serve a specific function.
• They were able to find two regions in the VP7 sequence and twelve in the VP4 sequence, which were representative of the evolutionary footprints of L338.
• These ‘footprints’ provide insights about the evolutionary history and genetic variation of the strain.
• All 27 G and 37 P type genotypes were identified in specific regions of VP7 and VP4, further indicating the unique genetic makeup of this strain.