RETROSPECTIVE DIAGNOSIS OF BLUETONGUE VIRUS IN STORED FROZEN AND FIXED TISSUE SAMPLES USING PCR

Stored frozen ( - 70 degrees C) and formalin-fixed tissue samples cons titute a valuable resource for retrospective studies of infectious dis eases, or for diagnostic investigations. The polymerase chain reaction (PCB) affords an accurate and rapid method for detection of viral nuc leic acids. It was applied to stored tissue samples collected from she ep inoculated with two Australian serotypes of bluetongue virus, BTV 1 and 23, and two North American serotypes, BTV 11 and 17. Specific nes ted PCR products were detected in both frozen and formalin-fixed sampl es from the Australian sheep after storage for 3.5 years. The tissues from sheep inoculated with the North American serotypes yielded specif ic nested PCR products after storage at - 70 degrees C for 14 years. N o specific primary PCR products were detected in any frozen or formali n-fixed samples. The PCR assay offers a potential benefit for epidemio logical studies, and for screening of stored semen, embryos and tissue banks.