Ongoing Change Of Hand,Foot,and Mouth Disease Pathogens For Hospitalized Pediatric Patients In Yunnan,China

Objective:Hand,foot,and mouth disease(HFMD)is a common infectious disease caused by enteroviruses(EV)and occurs mainly in children under 5 years of age,and has become a serious public health concern in mainland China.This study aimed to investigate the etiologic spectrum,clinical character and molecular characteristics of HFMD for hospitalized pediatric patients in Yunnan Provience.Methods:Stool specimens and clinical data were collected from pediatric patients hospitalized for treatment of HFMD in a children's hospital from 2010 and 2012 to 2016.After viral RNA was extracted,the EV was detected by Semi-nested reverse transcription PCR(snRT-PCR)and directly genotyped by gene sequencing of partial VP1 region.The detection result and the clinical data were analyzed by the SPSS20.0 software.Homology of nucleotide and amino acid sequence of the predominant serotypes were compared with other domestic and foreign strains,and phylogenetic analyses were performed using MEGA7.0 software.In addition,Rhabdomyosarcoma cell(RD)?Human lung cancer cell(A549)and Human embryonic lung diploid fibroblasts cell(KMB17)were used for viral isolation,then the complete genomes were amplified and sequenced,the evolutionary analysis and recombination analysis were carried out by MEGA 7.0 and Simplot 3.5.1 software.Results:1.1280 stool specimens were collected from pediatric patients hospitalized for treatment of HFMD in 2010,with 799 males and 481 females.The examination of stool specimens from these 1280 patients revealed the presence of EV in 1115 cases,a total of 17 serotypes of EV were detected and all of them can cause severe symptoms.CA16(615/1115,55.1%),EV71(392/1115,35.2%),CA10(45/1115,4.0%)and CA4(23/1115,2.1%)were main causative agent,phylogenetic analyses showed that these viruses belonged to the C4a,B1a,G and C genotypes,respectively.2.341 severe cases were collected from 2012-2016,of which 283(83.0%)were positive for EV,with 191 males and 150 female cases.A total of 17 serotypes of EV were detected,the main pathogens were EV71(142/341,41.6%),CA16(64/341,18.8%)and CA6(31/341,9%).All of EV71,CA16 and CA6 isolates belonged to the epidemic strains in mainland China.3.Moreover,two echoviruses 18(E18)were successfully isolated by cell culture,and their complete nucleotide sequence was determined.Analysis showed that both of them belong to recombinant strain.Conclusion:The molecular epidemiology and etiology of HFMD in Yunnan Provience were similar to other South China region,EV71 and CA16 were main pathogens of HFMD,but other EVs,such as CA10,CA6 and CA4,also had high incidence of this disease.Thus,continuous monitoring is still needed in the future.