ISOLATION, MOLECULAR CHARACTERIZATION AND VACCINE MATCHING OF FOOT-AND-MOUTH DISEASE VIRUS CIRCULATING IN ETHIOPA
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2014-06
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Abstract
Foot-and-mouth disease (FMD) is a highly contagious viral and economically important disease that infects wide variety of domestic and wild life hosts and occurs as multiple non cross-protective virus serotypes. FMD suspected samples were collected from Addis Ababa, Debre Berhan and Debre Zeit, with the aim of Isolation, identification of FMDV serotype and conduct vaccine matching. FMD virus was isolated on Baby Hamster Kidney cell culture at National Veterinary Institute (NVI). From the total of 32 samples (22 swine foot epithelium, 8 bovine tongue epithelium and 2 vesicular fluid samples) which were obtained from eight field FMD outbreaks, 21 (65.63%) samples showed cytopathic effect (CPE). Further analysis using Reverse Transcription Polymerase Chain Reaction (RT- PCR) at National Veterinary Institute (NVI) revealed that the FMD field outbreaks reported in this study were caused by FMDV serotype O and one of each serotype O, A and SAT2 were vaccine strains but not field samples included in the study. Two isolates from each outbreak were matched by two dimensional virus neutralization test (2dm VNT) in order to check the antigenic similarity of the field isolate to the vaccine strain. The result indicated that vaccine strains found at National Veterinary Institute (NVI) can protect against field serotype O of Ethiopia isolate except ETH03/12 and ETH04/12 had antigenic variation from the vaccine strain. The finding discovered most of the field isolates have antigenic similarity with the average “r1” value = 0.60 with the vaccine strain. Therefore, FMDV serotype O caused the outbreak in the sample collecting area which were antigenically similar with the vaccine strain and vaccine produce at NVI was still protecting the existing outbreak but further study of antigenic match conducted at certain interval covering a wide area and targeting different animal species since the virus serotype circulating in the country might be changed and all the dominant circulating viruses are incorporated into the vaccine formulation.
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Ethiopia, Foot-and-Mouth Disease virus, FMDV isolation, FMD Serotypes