Investigation On The Epidemiology Of Infantile Diarrhea Disease Virus And The Characteristics Of Astrovirus In Kunming City

Diarrhea is the second diseases commonly and frequently occurred in children and infants in developing countries, such as China. Diarrhea disease may be caused by various pathogens, including parasites, bacteria and viruses.72% infantile diarrhea is caused by viruses. This paper investigates the epidemiology of human norovirus (HNV), human astrovirus (HAstV), human rotavirus (HRV), in Kunming City. The complete genome of HAstV was been amplified by reverse transcription PCR method (RT-PCR), 12 samples of positive HAstV have been selected, and structural protein ORF2 of HAstV have been amplified in order to do preliminary research on infantile diarrhea in Kunming City.Firstly,63 feces samples and 42 controls were detected by RT-PCR. Results show that positive rate of HNV, HAstV and HRV was 20.63%,41.73% and 34.92% respectively, while, HNV and HRV were negative and only 1 sample positive to HAstV (2.38%).Secondly, by using RT-PCR method to amplify HAstV genome, the complete genome with the length of 6.9 kb has been get and named KM-02. Though comparing the complete genome nucleotide and constructing the phylogenetic tree, it is found that homology of KM-02 with HQ398856 was 98.2%, which shows that KM-02 is a HAstV1 type. Moreover, the homology of KM-02 with Kunming strain KC342249 is 88.7%, which shows that epidemic strains differs in different time.Finally,12 strains HAstV ORF2 sequences have been identified from HAstV positive samples by RT-PCR method. By comparing their nucleic acid and amino acid, and analyzing physical and chemical properties, level 2 and level 3 structure etc. in the linear ORF2 database using relevant biological software and protein structure prediction websites, it is found that the protein ORF2 has stable physical and chemical characteristics and good antigenicity.In conclusion, the epidemiology of diarrhea in infant in Kunming district from 2013 to 2014 has been investigated and studied, which has enriched the relevant database of viral diarrhea in the south of China and provided theoretical basis for the infection and control of viral diarrhea. Moreover, by amplifying the whole genome of HAstV and analyzing the ORF2 protein, this study has provided scientific basis for the detection, origin, immune escape and vaccine development of HAstV.