Comparative thermostability of West Nile, St. Louis encephalitis, and western equine encephalomyelitis viruses during heat inactivation for serologic diagnostics.
During the monitoring of arbovirus seroprevalence in wild birds collected in California, we inadvertently made two isolates of western equine encephalomyelitis virus (WEEV) from California quail sera being tested by plaque reduction neutralization assay for antibodies against St Louis encephalitis (SLEV) and West Nile (WNV) viruses despite heating the sera at 56 degrees C for 30 minutes. These data prompted us to examine the thermostability of these viruses during heat treatment. The flaviviruses, SLEV and WNV, at titers up to 10(6) plaque-forming units (PFU), were readily inactivated by the standard protocol of heating at 56 degrees C for 30 minutes. In contrast, solutions containing 10(5) and 10(6) PFU of WEEV required 2 hours for complete inactivation. Occasional presence of live virus within sera could lead to false negatives using standard plaque reduction neutralization test protocols.
Fang
Ying
Y
Center for Vectorborne Diseases and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California 95616, USA.
Brault
Aaron C
AC
Reisen
William K
WK
D000818:Animals; D001715:Bird Diseases / Q000175:diagnosis / Q000276:immunology / Q000821:virology; D003370:Coturnix; D004665:Encephalitis Virus, St. Louis / Q000502:physiology*; D004667:Encephalitis Virus, Western Equine / Q000502:physiology*; D004674:Encephalitis, St. Louis / Q000097:blood / Q000175:diagnosis / Q000662:veterinary; D020241:Encephalomyelitis, Western Equine / Q000097:blood / Q000175:diagnosis / Q000662:veterinary; D006358:Hot Temperature; D012698:Serologic Tests; D013048:Specimen Handling / Q000379:methods*; D014901:West Nile Fever / Q000097:blood / Q000175:diagnosis / Q000662:veterinary; D014902:West Nile virus / Q000502:physiology*