An Imported Case of COVID-19 Delta Variant B.1.617.2---Guangxi Zhuang
Autonomous Region, China, June 8, 2021
Abstract
A male passenger arriving at Nanning Wuxu Airport in Guangxi on an
international flight from Jakarta, Indonesia, was found to be positive
for SARS-CoV-2 nucleic acid on a routine test at the airport on June 8
2021. The passenger was sent to Fourth People’s Hospital of Nanning
immediately for further isolation and observation. On the day of
admission, the test for SARS-CoV-2 nucleic acid of nasopharyngeal swabs,
pharyngeal swabs and sputum specimens were positive (CT values of N gene
and ORF1ab gene were between 20 and 30). After 8 weeks of
hospitalization, the patient’s test for SARS-CoV-2 nucleic acid of all
specimens turned to negative. We isolated a SARS-CoV-2 variant strain
from the nasal swab of the patient, and then we found that the genome
sequence of the variant strain had 13 base deletions and 38 nucleotide
mutations compared with that of the Novel Coronavirus Wuhan strain after
sequencing, comparison and analysis. The deletions and mutations of the
variant strain resulted in four amino acid deletions and 30 amino acid
mutations. Furthermore, we found that the variant strain was similar to
those from Indonesia, South Korea and The United Kingdom after
conducting BLAST analysis on GISAID platform, among them, hCOV-19
/Indonesia/ Ji-ITD-43591N /2021 was the most similar, with 99.98%
similarity and only 8 base differences. The maximum likelihood
phylogenetic tree was constructed taking the Wuhan strain as the root
and including most the reference sequence contained most of the epidemic
strains. The result showed that the strains isolated in our laboratory
belonged to Delta strain.