Objective GenomeLab Genetic Analysis System (GeXP) and multiplex-PCR were combined to detect Noroviruse Ⅰ、Ⅱ,Astrovirus and Rotavirus.Methods The sequences of these viruses were obtained from Genbank of NCBI,and specific primer pairs were designed by GeXP eXpress Profiler.After optimization,the GeXP system could amplify specific fragments of each virus.The sensitivity and specificity of multiple PCR assay was also evaluated.Optimized assay was further validated with 120 clinical specimens collected from the CDC.Results These primer pairs were successfully used for detecting these viruses at the level of 5 × 103copies/ μl without cross reaction.The sensitivity,specificity and efficiency of GeXP assay was 100％,99.53％ and 99.62％,respectively.Comparing to Real-time PCR,the consistence rate reached 99.51％ in 120 clinical samples.Conclusions The combined detection of GeXP and multiplex PCR assay could be a high-throughput,rapid and highly specific and sensitive method used in the screening of the diarrhea viruses.

Objective:To analyze the distribution and genomic characteristics of SARS-CoV-2 variants isolated from imported cases of COVID-19 in Sichuan Province from December 2022 to January 2023.Methods:This study selected 108 nasal and throat swab samples with fluorescence threshold (Ct)≤32 that were collected from imported COVID-19 cases in Sichuan Province from December 2022 to January 2023. Targeted amplification and Illumina NextSeq? 2000 system were used for whole-genome sequencing. Nextclade and Pangolin online platforms were used to determine the virus genotypes and analyze the mutation loci. A phylogenetic tree was constructed using maximum likelihood.Results:A total of 55 SARS-CoV-2 whole genome sequences with coverage of >95% were obtained, and all of the strains were Omicron variants. Compared with the sequence of reference strain Wuhan-Hu-1, the median number of nucleotide mutation sites of 21L, 22B, 22D, 22E, and 22F genotypes were 93, 75, 92, 78, and 92, and the median number of amino acid mutation sites were 68, 53, 68, 69, and 65, respectively. From December 2022 to January 2023, the predominant circulating SARS-CoV-2 variants from imported cases in Sichuan Province were BA.5.2 (10.91%, 6/55), XBB.1.1 (9.10%, 5/55), BF.7.14 (7.23%, 4/55), and BQ.1.1 (7.23%, 4/55).Conclusions:The distribution of SARS-CoV-2 variants can reflect the global epidemic trend to a certain extent. However, it is different from the distribution of local circulating variants in the Chinese mainland. The XXB variants with transmission advantages can be detected in large numbers of inbound travelers before becoming the predominant circulating strains in the Chinese mainland.