Virus Isolation And Genotype Identification Of Human Respiratory Syncytial Virus In Guizhou Province

Objective: Human respiratory syncytial virus(HRSV)is one of the most important viral pathogens that cause severe acute lower respiratory tract infection(ALRTI)in infants and young children worldwide.Separate cultivation and genetic variation analysis of HRSV in infants and young children in Guizhou from December 2017 to March 2018 can grasp the molecular epidemiological characteristics of HRSV in Guizhou,and analyze their clinical characteristics to determine whether genotypes are related to clinical characteristics and disease status.Provide an important basis for the prevention and control of respiratory tract infections caused by HRSV in Guizhou.Methods: The nasopharyngeal secretions of patients with acute respiratory infection admitted to Guizhou Provincial Third-class Hospital from December 2017 to March 2018 were collected.Nasopharyngeal secretion specimens were inoculated into Hep-2 cells to isolate HRSV.Cells showed cytopathic effect(CPE)were then confirmed by indirect immunofluorescence assay(IFA)and reverse transcription polymerase chain reaction(RT-PCR).The DNA sequences of PCR products of HRSV isolates were sequenced,genotype identification,nucleotide and amino acid homology sequence analysis,phylogenetic analysis and amino acid variability was analyzed of HRSV isolates in Guizhou.The SPSS22.0 data analysis software was used to analyze the clinical characteristics of HRSV subgroup A and B genotypes.Results: A total of 196 nasopharyngeal secretion specimens were collected from October 2017 to March 2018.39 viruses were isolated and confirmed to be HRSV by IFA and RT-PCR.The second hypervariable region at the 3' terminal of glycoprotein gene(HVR2)sequence analysis showed that subgroup A was dominant in HRSV infection in Guizhou.Seventy nine percent of the isolates belonged to subgroup A,ON1 genotype,and 21% belonged to subgroup B,BA9 genotype.The nucleotide and amino acid homology between subgroup A isolates and subgroup A standard strain A2 was 86.1%?87.9% and 79.6%?81.6% respectively,while the nucleotide and amino acid homology between subgroup B isolates and subgroup B standard strain CH18537 was 76.9%?83.8% and 61.1%?70.1% respectively.All subgroup A have insertions of 24 amino acid sequences with an amino acid length of 321 aa,and subgroup A have insertions of 20 amino acids with an amino acid length of 312 aa.Preliminary clinical analysis shows that the positive detection rate of HRSV has no statistical significance with the age and sex of the children,and there is no statistically significant difference between the clinical symptoms of the different subtypes and the children and the rate of severe pneumonia caused by the infection.Conclusion: This is the first systematic analysis of the isolation and genetic variation of HRSV in Guizhou.From December 2017 to March 2018,HRSV circulating in Guizhou Province was dominant with subgroup A,co-circulating with a small portion of subgroup B.The dominant genotype of subgroup A is ON1,and the dominant genotype of subgroup B is BA9.