Human norovirus causes sporadic and epidemic acute gastroenteritis worldwide, and the predominant strains are genotype GII.4 variants. Recently, a novel GII.17[P17] and a recombinant GII.2[P16] strain have been reported as the causes of gastroenteritis outbreaks. Outbreaks of norovirus are frequently associated with foodborne illness. In this study, each of 75 oyster samples processed by a proteinase K extraction method and an adsorption-elution method were examined for noroviruses using RT-nested PCR with capsid primers. Thirteen (17.3%) samples processed by either method tested positive for norovirus genogroup II (GII). PCR amplicons were characterized by DNA sequencing and phylogenetic analysis as GII.2 (n = 6), GII.4 (n = 1), GII.17 (n = 3), and GII.unclassified (n = 3). Norovirus-positive samples were further amplified by semi-nested RT-PCR targeting the polymerase-capsid genes. One nucleotide sequence revealed GII.17[P17] Kawasaki strain. Five nucleotide sequences were identified as belonging to the recombinant GII.2[P16] strains by recombination analysis. The collected oyster samples were quantified for norovirus GII genome copy number by RT-quantitative PCR. Using the proteinase K method, GII was found in 13/75 (17.3%) of samples with a range of 8.83–1.85 × 10⁴ genome copies/g of oyster. One sample (1/75, 1.3%) processed by the adsorption-elution method was positive for GII at 5.00 × 10¹ genome copies/g. These findings indicate the circulation of a new variant GII.17 Kawasaki strain and the recombinant GII.2[P16] in oyster samples corresponding to the circulating strains reported at a global scale during the same period of time. The detection of the recombinant strains in oysters emphasizes the need for continuing systematic surveillance for control and prevention of norovirus gastroenteritis.

人类诺如病毒在世界范围内引起散发性和流行性急性胃肠炎，主要毒株是基因型 GII.4 变体。最近，据报道，一种新型 GII.17[P17] 和一种重组 GII.2[P16] 菌株是导致肠胃炎暴发的原因。诺如病毒的爆发经常与食源性疾病有关。在这项研究中，使用带有衣壳引物的 RT 巢式 PCR，对通过蛋白酶 K 提取法和吸附洗脱法处理的 75 个牡蛎样品中的每一个样品进行了诺如病毒检测。用这两种方法处理的 13 个 (17.3%) 样本检测出诺如病毒基因组 II (GII) 呈阳性。PCR扩增子通过DNA测序和系统发育分析表征为GII.2（n  = 6），GII.4（n  = 1），GII.17（n = 3) 和 GII.unclassified ( n  = 3)。诺如病毒阳性样本通过靶向聚合酶衣壳基因的半巢式 RT-PCR 进一步扩增。一个核苷酸序列揭示了 GII.17[P17] Kawasaki 菌株。重组分析鉴定出5个核苷酸序列属于重组GII.2[P16]菌株。通过 RT 定量 PCR 对收集的牡蛎样品进行诺如病毒 GII 基因组拷贝数的定量。使用蛋白酶 K 方法，在 13/75 (17.3%) 的样本中发现了 GII，范围为 8.83–1.85 × 10 ^{4 个}基因组拷贝/g 牡蛎。经吸附-洗脱法处理的一份样品（1/75, 1.3%）在 5.00 × 10 ^{1时 GII 呈阳性}基因组拷贝数/g。这些发现表明，牡蛎样本中存在新变种 GII.17 Kawasaki 菌株和重组 GII.2[P16]，对应于同期在全球范围内报道的循环菌株。牡蛎中重组菌株的检测强调需要继续进行系统监测以控制和预防诺如病毒胃肠炎。