Characterization of capsid genes, expressed in the baculovirus system, of three new genetically distinct strains of "Norwalk-like viruses".
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"Norwalk-like viruses" (NLVs), members of a newly defined genus of the family Caliciviridae, are the most common agents of outbreaks of gastroenteritis in the United States. Two features of NLVs have hindered the development of simple methods for detection and determination of serotype: their genetic diversity and their inability to grow in cell culture. To assess the immune responses of patients involved in outbreaks of gastroenteritis resulting from infection with NLVs, we previously used recombinant-expressed capsid antigens representing four different genetic clusters, but this panel proved insufficient for detection of an immune response in many patients. To extend and further refine this panel, we expressed in baculovirus the capsid genes of three additional genetically distinct viruses, Burwash Landing virus (BLV), White River virus (WRV), and Florida virus. All three expressed proteins assembled into virus-like particles (VLPs) that contained a full-length 64-kDa protein, but both the BLV and WRV VLPs also contained a 58-kDa protein that resulted from deletion of 39 amino acids at the amino terminus. The purified VLPs were used to measure the immune responses in 403 patients involved in 37 outbreaks of acute gastroenteritis. A majority of patients demonstrated a fourfold rise in the titer of immunoglobulin G to the antigen homologous to the outbreak strain, but most seroconverted in response to other genetically distinct antigens as well, suggesting no clear pattern of type-specific immune response. Further study of the antigenicity of the NLVs by use of VLPs should allow us to design new detection systems with either broader reactivity or better specificity and to define the optimum panel of antigens required for routine screening of patient sera. (+info)
Norwalk-like virus outbreaks at two summer camps--Wisconsin, June 2001.
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On June 27 and 28, 2001, the Wisconsin Division of Public Health was notified by two local health departments of outbreaks of gastroenteritis at two summer recreational camps (camps A and B) in northern Wisconsin. This report summarizes the investigation of these outbreaks, which documents person-to-person transmission of "Norwalk-like virus" (NLV) and underscores the importance of cleaning environmental surfaces and the availability and use of hand-washing facilities at recreational camps. (+info)
Food-borne outbreak of gastroenteritis associated with genogroup I calicivirus.
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An outbreak of gastroenteritis affecting 158 of 219 (72%) guests and employees at a hotel is described. Food served at the hotel restaurant is believed to have been the source of the outbreak and to have been contaminated by sick employees working in the restaurant. A secondary attack rate of 22% was seen involving 43 persons in all. In stool specimens from seven of eight patients, Norwalk-like viruses (NLVs) were detected by electron microscopy. While NLV-specific PCR using primers JV12 and JV13 were negative, all specimens examined with primers NVp69 and NVp110 were positive. The failure of primers JV12 and JV13 was attributed to several mismatches in the JV12 primer. Genotyping and sequence analysis revealed that all samples had identical sequences and clustered with genogroup I, and the most closely related well-characterized genotype is Desert Shield. This is the first described food-borne outbreak associated with genogroup I virus in Sweden. (+info)
An etiological investigation of domestic cats with conjunctivitis and upper respiratory tract disease in Japan.
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Chlamydophila felis (C. felis), feline herpesvirus-1 (FHV-1) and feline calicivirus (FCV) were detected in 39 (59.1%), 11 (16.7%) and 14 (21.2%) cats respectively, from 66 domestic cats presented with conjunctivitis and upper respiratory tract disease (URTD) in 9 prefectures of Japan. Dual and multiple infections were found in 7 (10.6%) cats with both C. felis and FHV-1, 10 (15.2%) cats with both C. felis and FCV, and 1 (1.5%) cat with all three agents. C. felis was isolated from 11 (28.2%) of 39 PCR positive cats. Antigenic difference was found in a 96 kDa protein of our isolates and Fe/145 strain isolated in USA. In conclusion, C. felis is the most common agent of feline conjunctivitis and URTD, and the coinfection with C. felis, FHV-1 and FCV are also common in cats in Japan. (+info)
Norwalk virus infection and disease is associated with ABO histo-blood group type.
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Some people are resistant to Norwalk virus (NV) infection; however, the factor(s) responsible for resistance or susceptibility to NV infection has not been identified. This study investigated the relationship between a person's ABO histo-blood group type and the risk of NV infection and symptomatic disease after clinical challenge. ABO phenotypes were identified by using serum samples from volunteers who participated in an NV challenge study (n=51). Individuals with an O phenotype were more likely to be infected with NV (odds ratio [OR], 11.8; 95% confidence interval [CI], 1.3-103), whereas persons with a B histo-blood group antigen had decreased risk of infection (OR, 0.096; 95% CI, 0.16-0.56) and symptomatic disease (OR, 0; 95% CI, 0-0.999). This is the first report demonstrating an association between a genetic factor and the risk of NV infection and symptomatic disease. (+info)
Waterborne outbreak of Norwalk-like virus gastroenteritis at a tourist resort, Italy.
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In July 2000, an outbreak of gastroenteritis occurred at a tourist resort in the Gulf of Taranto in southern Italy. Illness in 344 people, 69 of whom were staff members, met the case definition. Norwalk-like virus (NLV) was found in 22 of 28 stool specimens tested. The source of illness was likely contaminated drinking water, as environmental inspection identified a breakdown in the resort water system and tap water samples were contaminated with fecal bacteria. Attack rates were increased (51.4%) in staff members involved in water sports. Relative risks were significant only for exposure to beach showers and consuming drinks with ice. Although Italy has no surveillance system for nonbacterial gastroenteritis, no outbreak caused by NLV has been described previously in the country. (+info)
Outbreak of acute gastroenteritis associated with Norwalk-like viruses among British military personnel--Afghanistan, May 2002.
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In the United States, Norwalk-like viruses (NLVs) cause an estimated 23 million episodes of illness, 50,000 hospitalizations, and 300 deaths each year. NLVs can be transmitted by fecally contaminated food and water and by direct person-to-person contact or through droplets of infected persons. Outbreaks of NLV-associated gastrointestinal illness are common in military settings. During May 13-19, 2002, a total of 29 British soldiers and staff of a field hospital in Afghanistan became acutely ill after a short incubation period with vomiting, diarrhea, and fever. This report summarizes the investigation of this outbreak and underscores the importance of the diagnostic capacity for NLVs. (+info)
Cross-reactivity among several recombinant calicivirus virus-like particles (VLPs) with monoclonal antibodies obtained from mice immunized orally with one type of VLP.
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Human caliciviruses (HuCVs) are classified into the Norwalk-like viruses (NLV) and Sapporo-like viruses (SLV) as genera within the family CALICIVIRIDAE: The NLV genus is further classified into genogroups I and II, based on sequence similarities. To study the antigenic determinants on the HuCV capsid protein and develop new diagnostic tools for field samples, we established and characterized monoclonal antibodies (MAbs) against baculovirus-expressed recombinant HuCV virus-like particles (VLPs). Hybrid clones producing MAbs were obtained from cultures of PAI myeloma cells fused with spleen or mesenteric lymph node cells from mice immunized orally with either a single type of recombinant Norwalk virus (rNV), Kashiwa 47 virus (rKAV), Snow Mountain agent (rSMA), or Sapporo virus (rSV) VLP or with mixtures of two types of VLPs from different genogroups. Twenty MAbs, obtained as mouse ascites, were characterized and classified into six groups according to their enzyme-linked immunosorbent assay (ELISA) and Western blotting (WB) cross-reactivity patterns to VLPs. Five groups of MAbs reacted by both WB and ELISA and were classified as follows: common cross-reactive MAbs for four genogroup I and six genogroup II VLPs (group A), genogroup I-specific MAbs (group B), genogroup II-specific MAbs (group C), and strain-specific MAbs (groups D and E). One MAb group (group F) reacted only by ELISA. The group A MAbs, which showed broad cross-reactivity with VLPs of both NLV genogroups, were obtained from mice immunized orally with a single type of VLP (either rNV or rKAV). Two MAbs, which were obtained from mice immunized with rSV, reacted with rSV but not with any NLV VLP. These are the first MAbs to be reported for any SLV. These strain-, genogroup-, and genus-reactive MAbs will be useful tools for further study of the antigenic and structural topography of the HuCV virion and for diagnostic assays for HuCVs. (+info)