3.3 The BLAST and phylogenetic analyses of the VP7 and VP4 genes
of the G8P[8] strains
The VP7 and VP4 genes of 14 G8P[8] strains were first subjected to
nucleotide sequencing and phylogenetic analysis. According to the BLAST
analysis, the VP7 gene of the G8 strains had nucleotide sequence
similarity of 100% with a Thai
RVA/Human-wt/CMH-ST260-18/2018/G8P[8] strain. Phylogenetically, the
VP7 gene of G8 strains included in this analysis were divided into at
least 6 lineages (I-VI) (Figure 2A). All 14 G8 strains (or called
“Chiang Rai strain”), together with DS-1-like G8P[8] reference
strains (labelled with □) from several countries such as China, the
Czech Republic, Japan, Korea, Singapore, Taiwan, Thailand, and Vietnam,
belonged to the same lineage VI. The G8 strains detected in this study
formed a single sublineage A, most closely related to 11 G8P[8]
strains previously detected in Thailand in 2017-2019 and two G8P[8]
strains in China in 2021 with nucleotide sequence similarity of
98.7-100%.
The BLAST analysis revealed that the VP4 gene of 14 P[8] strains had
nucleotide sequence similarity of 100% with various Thai G3P[8],
G8P[8], and G9P[8] strains formerly reported in 2018-2019, such
as RVA/Human-wt/THA/B5117/2018/G3P[8],
RVA/Human-wt/THA/CMH-N004-19/2019/G8P[8],
RVA/Human-wt/THA/B4982/2018/G8P[8], RVA/
Human-wt/THA/DBM2018-291/2018/G9P[8], and
RVA/Human-wt/THA/CMH-ST139-18/ 2018/G9P[8]. Phylogenetically, the
VP4 gene of P[8] strains included in the present study were divided
into at least 5 lineages (I-V) (Figure 2B). All 14 P[8] strains,
together with DS-1-like G8P[8] reference strains (labelled with □)
and many other P[8] strains combined with different G-genotypes: G1,
G2, G3, G6, G8, G9, and G12, belonged to the same lineage V.