Isolation, Molecular Characterization and Sero-Prevalence Study of foot-and-Mouth Disease Virus Circulating in Central Ethiopia
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Date
2016-06
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Addis Ababauniversity
Abstract
A cross sectional study was conducted to determine sero-prevalence and to isolate and characterize causative agents of foot-and-mouth disease (FMD) in selected areas of Central Ethiopia from September 2015 to May 2016. In addition, the study was meant to assess epidemiological risk factors associated with FMD in dairy cattle. A multistage random sampling for the sero-prevalence study was implemented to select the required sample size. Blood sample was collected in vacutainer tubes for sera separation and the sera were tested by 3ABC-Ab ELISA. Outbreak cases were investigated by collecting epithelial tissues and by using oro-pharyngeal fluids samples for FMD virus isolation and characterization. The isolated viruses were used for antigen typing by sandwich ELISA. Molecular characterization was done by VP1 gene sequence generation and phylogenetic tree reconstruction. Laboratory results were analyzed using descriptive statistics, chi-square test and logistic regression. The overall sero-prevalence of FMD was 24.22% (139/574) for the dairy cattle. Sero-prevalence of 26.84% and 22.91% was recorded in Adama and Asella, respectively but not significantly different (P>0.05). In logistic regression analysis, breed, age and animal composition were significantly associated with FMD sero-prevalence (p<0.05). From the total of 378 cattle clinically examined during an outbreak, 109 (28.8%) of cattle showed signs and lesions suggestive of FMD infection. In this study, three serotypes (A, O and SAT-2) were isolated and serotyped FMD virus. From the isolated serotypes A and SAT2 viruses were characterized at molecular levels by phylogenetic reconstruction. The SAT2 virus shared greater than 90% genetic similarity with other SAT2 isolates reported previously from Ethiopia. The serotype A isolate has 87.79- 88.26% genetically similar with Cameron, Eritrea and Sudan isolates. This study generated useful information on FMD sero-prevalence, circulating serotypes, molecular characteristic of the isolates and associated risk factors. The isolated viruses clustered differently from the previously known isolates suggesting that they are variant viruses. Detailed molecular analyses coupled with protection potential of the existing vaccines against these isolates are recommended.
Key words: Ethiopia, dairy cattle, FMD virus, molecular characterization, sero-prevalence, risk factors
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Keywords
Ethiopia, dairy cattle, FMD virus, molecular characterization, sero-prevalence, risk factors