Serotype distribution of enteroviruses in child cases with influenza-like illness in Hangzhou city / 中华微生物学和免疫学杂志

ABSTRACT

Objective:To study the pathogenic spectrum of enterovirus (EV) in the samples of child influenza-like(ILI)cases in Hangzhou city .Methods:In 2019, 1 060 throat swab specimens of ILI cases were collected for serotyping of influenza virus and EVs by real-time RT-PCR. The positive rates of influenza virus and EV in spring, summer, autumn and winter were compared by chi-square test with SPSS16.0 software. Specific primers were synthesized and used to amplify the VP1 fragments of EV. PCR products were sequenced and the results were compared with the reference sequences by using Basic Local Alignment Search Tool (BLAST) to identify the serotypes of isolated EV. The clinical diagnoses of EV positive cases were classified and analyzed.Results:A total of 1 060 specimens were collected and 283(26.70%) were positive for influenza virus, 75(7.08%) were positive for EV, 3(0.28%)were positive for influenza virus and EV. The comparison of positive detection rate of spring, summer, autumn and winter showed that influenza virus were prevalent in winter and spring. EV were mostly popular in the summer months. VP1 sequences of 51 EV were successfully amplified and BLAST analysis revealed that these strains belonged to 10 serotypes, including five serotypes of EV-A species, four serotypes of EV-B species and one serotype of EV-D. The ten serotypes of EV, including coxsackievirus (CV)A2, A4, A5, A6, A9, A10, and echovirus (ECHO)7, ECHO11, ECHO18, and EV-D68 were obtained and the percentages of positive were 16.00%, 16.00%, 5.33%, 12.00%, 5.33%, 1.33%, 1.33%, 5.33%, 4.00% and 1.33%, respectively. The phylogram of EV VP1 sequence showed that 51 EV strains in Hangzhou had different degrees of variation compared with the reference strains. Acute upper respiratory tract infection was the main clinical diagnosis in EV positive children, with 44 cases (58.67%). Acute tonsillitis was followed by 14 cases (18.67%). Followed by herpetic pharyngitis, acute bronchitis, asthmatic bronchitis, pneumonia, accounting for 12.00%, 8.00%, 1.33%, 1.33%, respectively.Conclusions:EV causing influenza-like illness in children in Hangzhou in 2019 belonged to 10 serotypes, CVA2 and CVA4 were the predominant serotypes, and the positive rate of EV detection was higher in summer.