| Objective To investigate the pathogen spectrum and epidemic characteristics of viral acute respiratory infection(ARI)in Fuzhou,and to provide theoreticalbasis for disease prevention and control.To understand the genetic characteristics of respiratory syncytial virus(RSV),the main pathogen of ARI,and to provide some information for the development of vaccines and drugs.Methods1.The information of ARI cases in three different types of hospitals in Fuzhou during 2018-2020 was collected and respiratory tract specimens were collected.Real-time quantitative Polymerase Chain Reaction(PCR)or Reverse transcript-PCR(RT-PCR)was used.The nucleic acid of 15 viruses,including Adenovirus(ADV),Human Bocavirus(HBOV),Influenza A/B(Influenza A/B),were detected by RT-PCR.IFV-A/B),respiratory syncytial virus(RSV),parainfluenza virus 1-4(Parainfluenza virus 1-4,PIV-1～4),human metapneumovirus(HMPV),coronavirus(Co V)-229E/OC43/HKU1/NL63,Rhinoviruses(RV).Chi-square test and Fisher exact test were used to analyze the epidemiological characteristics of ARI cases.2.RT-PCR method was used to amplify and obtain the G gene and whole genome fragments of the RSV nucleic acid test positive samples and sequence them.Genetic evolution analysis and nucleotide and amino acid homology analysis of the virus sequences were conducted to observe whether amino acid mutations occurred in the important targets of vaccine and drug development.Results1.A total of 1061 ARI cases were collected from July 2018 to January 2020,and 424 of them(39.96%)were positive for viral nucleic acid.2.During the study period,the main viral pathogens prevalent in ARI cases in Fuzhou in different years were consistent,including RV,ADV and RSV.Among the other pathogens,IFV-A was the main pathogen in ARI cases in Fuzhou in the second half of 2018 and January 2020,and HMPV and PIV were the main parasyxoviruses in 2019.COVS and PIV-4 were less detected.The prevalence of RV(χ~2=7.99,P=0.01)and ADV(χ~2=5.21,P=0.02)was significantly higher in children than in men.The seasonal distribution of various viruses was observed.4.A total of 72 RSV positive nucleic acid cases were collected during the study period,and 53 G gene sequences were obtained by PCR amplification.NCBI BLAST results showed that ON1 and BA11 were the dominant genes in the early stage,and BA11 was the dominant gene in the autumn and winter of 2019.5.The nucleotide similarity(95.3%-99.8%)and nucleotide similarity(92.5%-100%)among ON1 genotypes(40 cases)and BA11 genotypes(13 cases)were high(97.3%-99.6%)and amino acid similarity(94.8%-99.7%).Compared with the ON1 prototype(JN257693)and BA11 prototype(AY333364),no nucleotide insertion or deletion was found,indicating high similarity.6.A total of 17 complete RSV genome sequences were obtained,10 of which were ON1 and 7 of which were BA11.Compared with the reference strain,the local cases had higher nucleotide and amino acid homology,no amino acid mutation was found on the important target of vaccine and drug development in G protein,and certain mutations were found on the antigen site and epitope of F protein.Conclusion Virus was an important pathogen in the cases of acute respiratory tract infection in Fuzhou from July 2018 to January 2021.The main prevalent viruses included RV,ADV,RSV,IFV-A,etc.,and the prevalence of other viral pathogens existed replacement phenomenon.The prevalence types of RSV cases collected in Fuzhou during the study period were ON1 and BA11(53 of 73 cases obtained clear typing information).Complete genome sequences were obtained in 17 cases(10cases were ON1,7 cases were BA11),and the similarity between the obtained isotypes and the prototype was high.There were certain amino acid mutations in F protein at the antigen site and epitope. |
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