Molecular characterization and the mutation pattern of SARS-CoV-2 during first and second wave outbreaks in Hiroshima, Japan.
PLoS One
; 16(2): e0246383, 2021.
Article
in English
| MEDLINE | ID: covidwho-1067425
ABSTRACT
BACKGROUND:
In this study, we performed molecular characterization of SARS-CoV-2 strains in Hiroshima and its mutation pattern between the first and second waves of the outbreak.METHOD:
A total of 55 nasal swab samples from the first wave in Hiroshima and 13 from the second wave were examined quantitatively by RT-qPCR and qualitatively by nested PCR using specific primers. Four samples from each wave underwent next-generation sequencing and phylogenetic tree analysis including controls and all sequences retrieved in Japan from GISAID and GenBank. Subsequently, mutations were examined.RESULTS:
Viral load ranged 7.85 × 101-1.42 × 108 copies/ml. Of 68 samples, one was Asian type-O, 65 were European type-GR, and 2 were undetectable. Phylogenetic tree analysis indicated that Japan was infected with various Asian strains (L, S, V, O) from January through April. By second week of March, European strains (G, GH, GR) had appeared, and GR strains became predominant after mid-March. The first case in Hiroshima was classified as Asian strain O, and the rest were GR strains. Then, second wave of GR strains appeared independently with 11-15 base mutations. Comparing the first- and second-wave GR strains, mutation rate was 1.17-1.36 × 10-3 base substitutions per site per year; in addition, amino acid changes occurred at S1361P and P3371S in ORF1a, A314V in ORF1b, and P151L in N. All seven GR strains were D614G variants with R202K and G203R mutations in N. A single-nucleotide insertion in ORF8 that causes a defect in ORF8 protein was found in one isolate (S66) from the second wave.CONCLUSION:
Our findings reveal the evolutionary hierarchy of SARS-CoV-2 in Japan. The predominant D614G variants and a new form of ORF8 deletion in Hiroshima provide the clue for role of viral factor in local outbreaks of SARS-CoV-2.
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
SARS-CoV-2
/
COVID-19
/
Mutation
Type of study:
Diagnostic study
/
Observational study
/
Qualitative research
/
Randomized controlled trials
Topics:
Variants
Limits:
Adult
/
Aged
/
Female
/
Humans
/
Male
/
Middle aged
/
Young adult
Country/Region as subject:
Asia
Language:
English
Journal:
PLoS One
Journal subject:
Science
/
Medicine
Year:
2021
Document Type:
Article
Affiliation country:
Journal.pone.0246383
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