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Human sapovirus is regarded as an important viral agent for acute diarrhea worldwide. GII.8, a recently reported genotype, has been detected in a few countries and regions. In this study, we obtained the first genome sequence of a sapovirus GII.8 strain isolated in mainland China, and comprehensively analyzed the genetic diversity and evolutionary process of this genotype. The viral genome of the new GII.8 Guangzhou strain GZ2014-L231 comprised 7433 nucleotides, including two ORFs. Pairwise alignments of the new genome with representative sequences of different genotypes showed inconsistent homology between different protein-encoding regions, of which NS1 and VP2 were found as the variable proteins, and NS3, NS5, and NS6/7 were found as the conserved ones. Compared with other reported GII.8 genomes, the Guangzhou strain introduced 34 new nucleotide changes and one new amino acid change. Phylogenetic analysis based on full-length VP1 sequences demonstrated that 11 GII.8 strains could be divided into 4 clusters A-D, with 88 SNP and 10 SAP spots occurred during their evolutionary process. The Guangzhou strain has higher homology with seven GII.8 strain detected after 2014, especially the US and Peruvian strains of 2015/2016, which have the identical VP1 amino acid sequences. Using a Bayesian coalescent method based on VP1 sequences, GII.8 was predicted to emerge in 2001 with the evolution rate of 1.45 × 10−3 nucleotide substitutions/site/year (strict clock). In summary, the data in this study not only provided reference data from mainland China for sapovirus researches in future, but also firstly described the evolutionary process of the GII.8 genotype. • The first genome sequence of GII.8 SaV from mainland China was obtained and analyzed. • The new Guangzhou genome employed 34 new SNP and one new SAP. • NS1 and VP2 were found as the variable proteins in the SaV genome. • GII.8 SaV could be further divided into four clusters based on the capsid VP1. • TMRCA and evolution rate for the capsid VP1 gene of GII.8 SaV was estimated. [ABSTRACT FROM AUTHOR]

Norovirus diarrhea is a great threat to public health worldwide. To characterize the prevalence of circulating noroviruses associated with sporadic gastroenteritis cases in Guangzhou, 215 stool specimens were collected during two consecutive cold seasons in 2013-2015. Noroviruses were detected in 25 (11.63 %) samples, and GII.4 (6/9) and GII.17 (10/16) were identified as the most predominant variants of each of those seasons. The remaining strains belonged to the genotypes GII.P12/GII.3, GII.2, and GI.Pb/GI.6. The phylogenetic relationships of the GII.17 strains were analyzed based on their capsid protein sequences. This study suggests a significant shift of predominant variants associated with sporadic gastroenteritis in Guangzhou. [ABSTRACT FROM AUTHOR]

Noroviruses are the primary cause of gastroenteritis and foodborne diseases, affecting millions of individuals annually worldwide. Oysters are frequently associated with norovirus outbreaks. Hence, inexpensive and simple norovirus detection methods are important to detect and contain foodborne illness outbreaks. The objective of this study is to develop a high-efficient concentrated pretreatment method for reverse transcriptase quantitative real-time polymerase chain reaction (RT-qPCR) detection. Based on the existing ISO/TS 15216-2:2013 standard (ISO/TS 15216-2., 2013), four methods are compared for recovery of norovirus from spiked digestive tissue of oysters. A method is found to be the most efficient based on protease K method of increasing buffer volume and PEG precipitation method. The recovery rate and amplification efficiency approached 11.07 ± 0.09% and 124.12 ± 5.99%, respectively, being 7-fold that of the original ISO/TS 15216-2:2013 method. This method serves as a rapid (1.5h) sample concentration tool with a limit of detection as low as 7.05 × 103 copies. Thirty-eight oyster samples from an aquatic products market in Guangzhou are tested using this method, and noroviruses are detected in 13 samples. This method is an effective extension of the existing ISO/TS 15216-2:2013 standard and it is potentially applicable for detecting norovirus contamination in oysters. • PEG precipitation with proteinase K treatment was performed to detect NoV in independent oysters. • This method had a higher recovery rate than the standard ISO/TS 15216-2:2013 method. • This method had a better amplification efficiency upon RT-qPCR-based monitoring. [ABSTRACT FROM AUTHOR]