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Coronavirus disease 2019 (COVID-19) has been a pandemic for more than a year.With the expanding second wave of the pandemic in winter,the continuous evolution of SARS-CoV-2 has brought new issues,including the significance of virus mutations in infection and the detection of asymptomatic infection.In this review,we first introduced several major SARS-CoV-2 mutations since the COVID-19 outbreak and then mentioned the widely used molecular detection techniques to diagnose COVID-19,primarily focusing on their strengths and limitations.We further discussed the effects of viral genetic variation and asymptomatic infection on the molecular detection of SARS-CoV-2 infection.The review finally sum-marized useful insights into the molecular diagnosis of COVID-19 under the special situation being challenged by virus mutation and asymptomatic infection.
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OBJECTIVE: To study the gene sequence characteristics of hantavirus in Heilongjiang Province in order to find out the reasons for the changes of clinical characteristics of hemorrhagic fever with renal syndrome in Heilongjiang Province in recent years.METHODS: Totally 110 rat lung specimens,121 blood specimens from patients diagnosed with mild or atypical HFRS and 100 blood specimens from patients diagnosed with typical HFRS in the First Affiliated Hospital of Harbin Medical University and the Seventh Hospital of Qiqihar City from 2005 to 2015 were collected. The gene sequences were obtained by nucleic acid extraction, RT-NestPCR, and gene sequencing. Explore the possible reasons for the changes in clinical characteristics of HFRS by comparing the obtained sequences with previous strains, homology analysis, building phylogenetic trees of M gene, and finding out the law of nucleotide and amino acid loci changes. RESULTS: TM gene of twenty-six mild or atypical HFRS patients were successfully amplified, including 14 cases of HTN type and 12 cases of SEO type; M gene of twenty-two typical HFRS patients were amplified, including 19 cases of HTN type and 3 cases of SEO type. Compared with the standard strain 76-118, the nucleotide homology of hantavirus from mild or atypical HFRS patients, typical HFRS patients and mice was 74.4%-89.2%, 87.4%-90.3% and 88.1%-88.5%. Comparing hantavirus gene sequence from mice and from patients, the nucleotide homology was 79.7-99.1%. Hljh38 and Hljh39 from patients were significantly different from the other strains. They were the same subtype as Amur virus because they had high homology with Amur strains H5 and H8205(94.9%-97.6%). The deduced amino acids showed some variations compared with the standard strains, but no obvious variation law was observed. CONCLUSION: The reason for the changes of clinical characteristics of hemorrhagic fever with renal syndrome in Heilongjiang province is related to the change of viral type. There are also variations of hantavirus and amino acid, but the relationship between specific variation law and clinical manifestations needs to be further verified.
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Objective To analyze the epidemiological characteristics of HFRS and rodent monitoring data in JiangXi province from 2012 to 2017, so as to provide scientific basis for controlling HFRS prevalence. Methods Descriptive epidemiological method was adopted to analyze the changes in time, region, and population morbidity of HFRS and rodent monitoring data from 2012 to 2017 in the province. Results From 2012 to 2017, there were 3 763 HFRS cases with 33 deaths reported in JiangXi province, the incidence was 1.38/100 000, the case fatality was 0.88%.The incidence in males was significantly higher than that in females( 2＝452.282, P<0.001).In the composition of occupation,the proprotion of farmers was decreased, while household workers, workers waiting for employment, students and other occupations were increased.There were two peaks in spring (from May to June) and winter (from November to January), and the winter peak was obviously higher than the spring peak. The average rat density at the two surveillance areas was 3.63%. Rattus norvegicus was predominant in residential areas and Apodemus agrarius was predominant in the wild.The six years on average index of rats with virus was 0.04. Conclusion The incidence of epidemic hemorrhagic fever in JiangXi Province generally showed an upward trend from 2012 to 2017, which suggest that we should continue to strengthen comprehensive prevention and control measures: rodent control in high-incidence areas, popularize vaccination and replenishment, and carry out health education for the whole population.
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Objective To investigate the relationship between HBV DNA and HBsAg blood group model by analyzing the sero logical and DNA sequences of serum samples.Methods Blood samples from 54 patients were selected from this hospital,collecting blood samples;on the HBV DNA extraction,PCR amplification,purification of PCR products,DNA sequencing,HBV gene analysis and sequence,and the use of bioinformatics software.The results were analyzed and compared the gene mutation.Results The results of PCR amplification,54 specimens in 40 cases showed significant PCR was poor,14 specimens were able to observe the electrophoresis of PCR amplified 1 400 bp specific band;22 cases were HBsAg ELISA positive,14 cases of occult HBV positive,PCR positive amplification for genotype,B genotype accounted for in 81.82 ％ HBsAg ELISA,C gene in occult HBV positive accounted for 78.57％ (P＜0.05);occult HBV gene of 14 strains,6 cases in the S area of the area occurred in the gene sequence of point mutations,including 2 cases in 1 base point mutations,the other 3 cases of base point in 2 sites the emergence of mutation;3 cases of HBV genotype C infected gene point mutation,2 cases of genotype B infected gene point mutation;5 cases were in the 9 site of the "a" family decided to base mutation,A-C mutation.Conclusion Blood screening,detection showed HBsAg negative blood qualified,may still have occult HBV infection and missed the window period,were mainly C type,B type and mutant strain is relatively less,but the mutant is relatively high,may escape the existing screening reagent.
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Objective To investigate the relationship between HBV DNA and HBsAg blood group model by analyzing the sero logical and DNA sequences of serum samples.Methods Blood samples from 54 patients were selected from this hospital,collecting blood samples;on the HBV DNA extraction,PCR amplification,purification of PCR products,DNA sequencing,HBV gene analysis and sequence,and the use of bioinformatics software.The results were analyzed and compared the gene mutation.Results The results of PCR amplification,54 specimens in 40 cases showed significant PCR was poor,14 specimens were able to observe the electrophoresis of PCR amplified 1 400 bp specific band;22 cases were HBsAg ELISA positive,14 cases of occult HBV positive,PCR positive amplification for genotype,B genotype accounted for in 81.82 ％ HBsAg ELISA,C gene in occult HBV positive accounted for 78.57％ (P＜0.05);occult HBV gene of 14 strains,6 cases in the S area of the area occurred in the gene sequence of point mutations,including 2 cases in 1 base point mutations,the other 3 cases of base point in 2 sites the emergence of mutation;3 cases of HBV genotype C infected gene point mutation,2 cases of genotype B infected gene point mutation;5 cases were in the 9 site of the "a" family decided to base mutation,A-C mutation.Conclusion Blood screening,detection showed HBsAg negative blood qualified,may still have occult HBV infection and missed the window period,were mainly C type,B type and mutant strain is relatively less,but the mutant is relatively high,may escape the existing screening reagent.