79 The Indian Veterinary Journal July 2010 J:\IVJ\2010\JUL_10\IVJ_7_3.PM5. PROOF II 79 As an Office International des Epizooties (OlE) List B disease, Infectious Bovine Rhoinotracheitis (IBR) is officially recognized as having international trade significance and socio-economic import- ance. The present study was undertaken to study the seroprevalence of IBR in cattle population of different rural unorganised sectors and organised cattle farms of West Bengal and to perform the end-point antibody titration of representative IBR positive serum samples Materials and Methods A total of six hundred ninety nine (699) blood samples were collected from different rural unorganised sectors (n = 264) and organised cattle farms (n=435) of West Bengal and screened for seropositivity of IBR by virus neutralization test (VNT) (OlE, 2000). The positive and negative control sera for VNT were procured from Institute of Animal Health and Veterinary Biologicals (Research and Training), Kolkata. Virus titration of standard bovine herpes virus-I (BHV-I), obtained from I.A.H. & V.B., Kolkata, was done in Madin Darby Bovine Kidney (MDBK) cell culture by ten-fold serial dilutions of the virus in Minimum Essential Medium (MEM: SIGMA) by considering at least five wells per dilution. The highest dilution of viruses exhibiting the 50% CPE was Indian Vet. J., July 2010; 87 : 711 - 712 SEROLOGICAL SURVEY OF INFECTIOUS BOVINE RHINOTRACHEITIS S. Ganguly and S.K. Mukhopadhayay* Department of Veterinary Microbiology, Faculty of Veterinary and Animal Sciences, West Bengal University of Animal and Fishery Sciences, Kolkatta, 700 037, India (Received : 27-12-2008; Accepted : 02-06-2009) considered to be 1 TCID 50 / 100 μ l. Accordingly, the titrated viruses were diluted and used in the VNT in the concentration of 100-200 TCID 50 / well. The district-wise seroprevalence (%) and sampling area-wise seroprevalence (%) were calculated from the number of samples found to be seropositive among the number of samples tested on district-wise and sampling area-wise study. Eighteen representative seropositive samples were subjected to end point titration or quantitative assay of IBR antibody by two- fold serial dilutions of the positive serum samples. Results and Discussion In the present study, the overall seroprevalence of IBR on district-wise study among the cattle population of West Bengal was found to be 48.15% with the lowest seroprevalence in Jalpaiguri district (20.72%) and highest in Nadia district (85.29%). On sampling area-wise study, the seroprevalence of IBR among the cattle population of West Bengal was estimated to be 42.32% with higher seroprevalence in organised cattle farms (61.15%) and 23.48 % in rural unorganised sectors. The seroprevalence of IBR in the present study was much lower than the findings of Babu et al., (1984) in which the seroprevalence (70.58%) was much higher than the present study. The result in present 1 Corresponding author. Email : skmpath@gmail.com Short Communications