The
Picornavirus
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Genera |
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| It now appears that the turkey entero-like virus
described by Guy and Barnes (1991) is actually turkey astrovirus 2
(Guy et al., 2004). Abstract from Guy and Barnes (1991)... Small round viruses, 18 to 24 nm in diameter, were detected by electron microscopy in droppings of young turkeys with enteritis. The virus was propagated in embryonated turkey eggs and tentatively identified as an enterovirus based on size, intracytoplasmic morphogenesis, buoyant density of 1.33 g/ml in CsCl, and a single-stranded RNA genome of approximately 7.5 kb. It was distinguished from avian encephalomyelitis virus by cross-immunofluorescence. These results identify an enterovirus-like virus as a possible etiologic agent of enteric disease of young turkeys. However, its role in this disease remains to be established. Abstract from Despins et al. (1994)... Larvae of the darkling beetle (lesser mealworm) were exposed to turkey feces from an enteritis-affected flock and determined to contain turkey enterovirus and rotavirus. Growth depression and increased mortality were observed in turkey poults which fed on the exposed larvae. Exposed larvae which had been surface-sterilized also produced clinical signs of enteritis after consumption by the poults, indicating that pathogens were able to survive within the larvae. This experiment demonstrated the capacity of the larva of the darkling beetle to serve as a mechanical vector for enteric pathogens of turkeys. Abstract from Guy et al. (2004)... A small round virus (SRV) was isolated in 1988 from droppings of enteritis-affected turkeys in North Carolina and tentatively identified as an enterovirus on the basis of size (18–24 nm in diameter), intracytoplasmic morphogenesis, and a single-stranded RNA genome of approximately 7.5 kb. Additional characterization studies based on antigenic and genomic analyses were done to determine the relationship of this turkey enterovirus-like virus (TELV) to turkey astrovirus 2 (TAstV2), a recently characterized SRV of turkeys. Cross-immunofluorescence studies with TELV- and TAstV2-specific antisera indicated a close antigenic relationship between these viruses. TELV RNA was amplified by reverse transcriptase–polymerase chain reaction (RT-PCR) procedures with oligonucleotide primers specific for TAstV2 polymerase gene (open reading frame [ORF] 1b) and capsid protein gene (ORF 2). Subsequent sequence analyses of these TELV-derived RT-PCR products indicated a high degree of similarity with polymerase gene (98.8%) and capsid gene (96.9%) of TAstV2. These studies definitively identify TELV (North Carolina, 1988 isolate) as TAstV2. References Despins, J.L., Axtell, R.C., Rives, D.V., Guy, J.S., Ficken, M.D. (1994). Transmission of enteric pathogens of turkeys by darkling beetle larva (Alphitobius diaperinus). J. Appl. Poultry Res. 3: 61-65. Guy, J.S. and Barnes, H.J. (1991). Partial characterization of a turkey enterovirus-like virus. Avian Dis. 35:197-203. Guy, J.S., Miles, A.M., Smith, L., Fuller, F.J. and Schultz-Cherry, S. (2004). Antigenic and genomic characterization of turkey enterovirus-like virus (North Carolina, 1988 isolate): identification of the virus as turkey astrovirus 2. Avian Diseases 48: 206-211. |