Surveillance And Analysis Of Norovirus In Mao Zhou River And In Its Nearby Acute Gastroenteritis Patients In Shenzhen, China

Aims:（1） The goal of the study was to surveil the norovirus（No V） infection in Maozhou River, and to compare the No V recovery effect of MCE-PEG and the Pathatrix.（2）Surveillance and analysis on the molecular epidemiology of No V in sporadic and outbreak acute gastroenteritis（AGE） cases in Maozhou drainage basin.（3） This study was aimed to figure out the No V epidemic strains in the water environment and human population in Shenzhen city, and to explore the homological relationship between the two media.Methods:（1） From March 2014 to February 2015, the river water was collected monthly from upstream and downstream of Mao Zhou River. They were concentrated by MCE-PEG and the Pathatrix system, respectively. The concentration effects were valued by real time RT-PCR and RT-PCR.（2）Stool specimens, collected from AGE patients from the outbreaks cases by CDC and the sporadic cases by the sentinel hospital, were eluted in Hanks’ buffer before the RNA isolated. Real time RT-PCR was applied to decide the GI and GII, and RT-PCR was performed for genotyping.（3） The nucleotide sequences, excluding the primer regions, were aligned with Clustal X, and genetic distances were calculated by Kimura’s 2-parameter method. A phylogenetic tree were generated by the Neighbor-joining method.Results:（1） The No V positive rate of downstream showed no significant difference to that of upstream（P>0.05）;（2） The infection season was April to September, 2014 and January 2015;（3）The positive rate of GI and GII（25%,16.67%）of MCE-PEG was higher than that（8.33%, 0%）of the Pathatrix（P<0.05）;（4） A total of 324 stool specimens from sporadic cases were collected in Shenzhen city from March 2014 to February 2015. Children younger than 1-year-old were the most susceptible group than other ages. The prevalent season was July to September. GII.4 Sydney₂012 was the mainly caustic agent of sporadic cases, and the second was GII.3.（5） There were 20 children（<5 years old） involved in GII.3 related AGE outbreak, which showed 99.5% homology with that in sporadic cases;（6） GI.6 was predominant in the river water samples, in which GII.4 Sydney₂012 was also detected. Meanwhile, compared with GII.3, GII.4 Sydney₂012 was more prevalent in human population. The homology of nucleotide and amino acid of N/S of GII.4 Sydney₂012 from different samples showed 98.2%-100.0%.Conclusions:（1） No V GI.6 and GII.4 Sydney₂012 were firstly detected from Maozhou river water;（2） The concentration effects of MCE-PEG was better than Pathatrix;（3） Children younger than 1-year-old were the most susceptible group than other ages. The prevalent season was July to September;（4） GII.4 Sydney₂012 was the predominant genotype in human population of Shenzhen city; the highly homology of GII.3 between sporadic and outbreak cases inferred that GII.3 was circulating in human population;（5） to some extent, the norovirus is probably circulating between water environment and human population.