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Chapter 27 : Foodborne Viral Pathogens
Category: Applied and Industrial Microbiology; Food Microbiology
Human enteric viruses have properties that are unique from those of bacterial foodborne pathogens. From an epidemiologic perspective, the noroviruses (NoVs) and hepatitis A virus (HAV) are the two most important enteric virus groups transmitted by foodborne routes. Human isolates of HAV comprise a single serotype, and monoclonal antibodies raised to different isolates fail to distinguish the isolates from one another. The rotaviruses usually are transmitted by either waterborne or person-to-person routes, but they can be food borne. This virus group is the leading cause of infantile diarrhea worldwide and is responsible for up to 130 million illnesses and 600,000 to 870,000 deaths per year, with the vast majority of rotavirus associated deaths occurring in developing countries. The contamination of produce items usually occurs before the product reaches food service establishments. The most commonly implicated bivalves are oysters, followed by clams, and it is now estimated that human enteric viruses are the most common disease agents transmitted by molluscan shellfish. Adherence to strict hygienic practices when handling and preparing foods is critical to control viral contamination of ready-to-eat (RTE) food products. A potential control strategy, albeit in developmental stages, would be the detection of viral contamination in foods. Improved and more widespread reporting and investigation of foodborne viral disease outbreaks, and targeted epidemiologic studies to identify the risk factors for viral gastroenteritis, would improve the understanding of attribution.
Key Concept Ranking
- Venezuelan equine encephalitis virus
Norwalk virus genome organization (adapted from Green et al. [ 84 ] with permission). VPg, genome-linked virion protein. ORF1 encodes polyprotein posttranslationally cleaved into nonstructural proteins helicase, with a predicted nucleoside triphosphate-binding domain (NTPase); proteinase (Pro); and RNA-dependent RNA polymerase (Pol). ORF2 encodes capsid protein, which is translated into major and minor structural proteins which consist of shell and protruding domains. N, NH2-terminal arm; S, shell. ORF3 encodes a basic protein of unknown function.
HAV genome organization (adapted from Hollinger and Emerson [ 98 ] with permission). 5′ untranslated region (624 to 1,199 nt long); VPg, genome-linked virion protein, 22 to 24 amino acids. The single open reading frame encodes polyprotein posttrans- lationally cleaved into VP1, VP2, and VP3, which form the capsid; VP4 is the inner surface capsid protein. 2A, unknown function; 2B, RNA synthesis and cell membrane permeability; 2C, RNA replication; 3A and 3B, RNA replication proteins, cofactor for 3D; 3C, viral proteinases; 3D, RNA-dependent RNA polymerase. Poly (A) tail, about 35 to 100 nt long. 3′ UTR, 3′ UTR, 5′ untranslated region (47 to 125 nt long).
Transmission routes of foodborne viruses.
Representative processing scheme for the concentration of viruses from complex food matrices (modification of method reported by Leggitt and Jaykus [ 127 ]). PEG, polyethylene glycol.
Representative viral foodborne disease outbreaks
Representative studies on enteric viral disinfection