ISOLATION, MOLECULAR CHARACTERIZATION AND VACCINE MATCHING OF FOOT-AND-MOUTH DISEASE VIRUS CIRCULATING IN CENTRAL ETHIOPIA
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Date
2017-06
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Abstract
The study was conducted Foot and Mouth Disease (FMD) outbreak reported in central part of Ethiopia namely Addis Ababa city council, Oromia Regional State of East Shoa zone and Amhara Regional State of North Shoa zone (Debre Berhan) from October 2016 to May 2017. It was designed with the objectives of identifying currently circulating serotypes and topotypes of foot and mouth disease viruses and to determine the antigenic relationship with FMD vaccine strains and newly isolated field isolate viruses. A total of 30 epithelial tissue samples were collected from cattle and used for virus isolation at National Veterinary Institute (NVI), Bishoftu. The samples were obtained from nine field FMD outbreaks, and 28 (93%) showed cytopathic effect (CPE) in BHK-21 cell culture. Of the total isolates, FMD viruses serotype O and SAT2 were identified using agarose gel based Reverse Transcription Polymerase Chain Reaction (RT- PCR) and 3 purified PCR products were send to international atomic energy for further molecular characterization for sequencing. The sequence results of serotype O FMDV isolates were used for phylogenetic tree reconstruction. The three isolates clustered with a single topotype, East Africa-4 (EA-4) with 99-100% similarity with each other. The five isolates from both serotypes, three O and two SAT2, were checked for their antigenic relatedness with the vaccine strain sera by vaccine matching test using one way testing (r1) by two-dimensional virus neutralization test. The finding discovered the entire tested field isolates have shown r1-value above the minimum requirement 0.3 compared to the vaccine strain which revealed antigenic match with vaccine strain. The mean r1- values were 0.79 and 0.82, respectively. Therefore, FMD vaccine containing serotype O and SAT2 produced by NVI still able to provide protection to the circulating field virus isolates in the study areas. Further work is recommended following the new outbreaks in other parts of the country.
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MSc Thesis
Keywords
Central Ethiopia, FMDV, Molecular characterization