The Epidemiological Investigation Of Bovine Viral Diarrhea Virus(BVDV) And Infectious Bovine Rhinotracheitis Virus (IBRV) And The Identification Of Isolated IBRV In Liaoning Province

In the study on the prevalence of bovine viral diarrhea virus (BVDV) and infectious bovinerhinotracheitis virus (IBRV) in Liaoning Province,665sera samples from cattles and202serasamples from sheep were collected in14cities of Liaoning Province. These samples were collectedfrom backyard farmers, slaughterhouses and livestock trading markets. For a serological survey, thesamples were detected for antibody prevalence against BVDV and IBRV, using a standard micro-serumneutralization test. Results demonstrated61.7%positive rate of antibody to BVDV (410out665) in thecattle and45.5%(92of202) in the sheep. Results of antibody to IBRV detection showed that positiverates were31.3%(206of659) in the cattle and12.2%(22of180) in the sheep. The serological resultsconfirmed that the cattle and sheep herds in Liaoning province have been already infected with BVDVand IBRV.During the study course, a suspected IBR case was detected in a cattle herd. The nasal swabs werecollected from the sick cattle and the samples were cultured in cell cultures for virus isolation. Theinfected MDBK celll cultures developed typical cytopathic effect (CPE) for IBRV, i.e. Round cellsshrink and net appearance and many cells connected to form a grape bunch shape. Further studies andidentifications by indirect immunofluorescence test, serum neutralization test and RT-PCR, the isolatedvirus strain was identified as a IBRV, and was named as IBR LN12/01. Additionally, the nucleotide ofgB gene from this IBR LN12/01strain was sequenced and analyses for further characterization.The serological surveys of BVDV and IBRV from the cattle and sheep populations in LiaoningProvince region provide a theoretical tool for the epidemic comprehensive prevention and control of theinfection and spreading of these viruses and the diseases caused by them. Isolation of the IBR LN12/01strain enableds us to firther deeply study and research the virusand it is a great local IBRV antigen fordevelopments of efficient diagnostic reagents and preventive biological products.