Herwaldt B L, Lew J F, Moe C L, Lewis D C, Humphrey C D, Monroe S S, Pon E W, Glass R I
Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333.
J Clin Microbiol. 1994 Apr;32(4):861-6. doi: 10.1128/jcm.32.4.861-866.1994.
A gastroenteritis outbreak affecting at least 217 (41%) of 527 passengers on a cruise ship was caused by a variant strain of Norwalk virus (NV) that is related to but distinct from the prototype NV strain. Consumption of fresh-cut fruit served at two buffets was significantly associated with illness (P < or = 0.01), and a significant dose-response relationship was evident between illness and the number of various fresh-cut fruit items eaten. Seven (58%) of 12 paired serum specimens from ill persons demonstrated at least fourfold rises in antibody response to recombinant NV capsid antigen. A 32-nm small round-structured virus was visualized by electron microscopy in 4 (29%) of 14 fecal specimens, but none of the 8 specimens that were examined by an enzyme immunoassay for NV antigen demonstrated antigen. Four (40%) of 10 fecal specimens were positive by reverse transcriptase-PCR by using primer pairs selected from the polymerase region of NV. In a 145-bp region, the PCR product shared only 72% nucleotide sequence identity with the reference NV strain and 77% nucleotide sequence identity with Southampton virus but shared 95% nucleotide sequence identity with UK2 virus, a United Kingdom reference virus strain. In addition, the outbreak virus was serotyped as UK2 virus by solid-phase immune electron microscopy. The genetic and antigenic divergence of the outbreak strain from the reference NV strain highlights the need for more broadly reactive diagnostic assays and for improved understanding of the relatedness of the NV group of agents.
一艘游轮上的肠胃炎疫情影响了527名乘客中的至少217人（41%），此次疫情由诺沃克病毒（NV）的一个变异株引起，该变异株与原型NV株相关但不同。在两个自助餐中供应的鲜切水果的食用与疾病显著相关（P≤0.01），并且在疾病与食用的各种鲜切水果项目数量之间存在明显的剂量反应关系。12份患病者配对血清标本中有7份（58%）对重组NV衣壳抗原的抗体反应至少有四倍升高。通过电子显微镜在14份粪便标本中的4份（29%）中观察到一种32纳米的小圆形结构病毒，但通过酶免疫测定检测NV抗原的8份标本中均未显示出抗原。10份粪便标本中有4份（40%）通过使用从NV聚合酶区域选择的引物对进行逆转录聚合酶链反应呈阳性。在一个145碱基对的区域中，聚合酶链反应产物与参考NV株的核苷酸序列同一性仅为72%，与南安普敦病毒的核苷酸序列同一性为77%，但与英国参考病毒株UK2病毒的核苷酸序列同一性为95%。此外，通过固相免疫电子显微镜将疫情病毒血清型鉴定为UK2病毒。疫情株与参考NV株的遗传和抗原差异突出了需要更具广泛反应性的诊断检测方法以及更好地理解NV类病原体的相关性。
