Phylogenetic analysis
The neighbor-joining phylogenetic tree in the Figure 1 shows a main
clade containing 5 clusters. The viral genome sequence of the female 22
year aged Bangladeshi patients (GISAID accession ID: EPI_ISL_437912)
was closely related to that of another 4 genome sample taken from the
four different Asian countries (GISAID accession ID: EPI_ISL_430111;
EPI_ISL_438966; EPI_ISL_425214; EPI_ISL_422227). These five genome
sequences were located in a cluster A.1 with genomes mainly from Asia
(Russia, Japan, Kuwait), but also one from Spain (Figure, highlighted in
blue). In cluster A, six other six genomes mainly from Asian countries
like Saudi Arabia (EPI_ISL_437762), Israel (EPI_ISL_435292), Turkey
(EPI_ISL_437335), Myanmar (EPI_ISL_434709) and one from United
Kingdom (GISAID accession ID: EPI_ISL_442502). Based on these
comparisons, it can be predicted that the circulating Bangladeshi
SARS-CoV-2 isolate published has phylogenetic relevance to some of the
Asian countries as well as Spain. In the tree, some sequences from other
SARS-CoV-2 collected in Asian countries segregated in separate clusters
from the one cluster containing the respective Bangladeshi sequences
characterized in this study. There was for example a cluster B formed by
8 sequences dominated by all Asian countries (Cambodia, Nepal, Malaysia,
Pakistan, and Indonesia) except one from USA. This cluster B also
contain the reference sequence from Wuhan, china (NC_045512.2). Cluster
C contain 6 genome sequences followed by Cluster D (2 genome sequences).
The two sequences (EPI_ISL_438138 and EPI_ISL_437438) retrieved from
the neighboring country of Bangladesh, India, which covers almost all
the direction except south (Bay of Bengal is in south) are in the
cluster E (Figure 1).