OUTBREAK INVESTIGATION, ISOLATION AND MOLECULAR CHARACTERIZATION OF SHEEP AND GOAT POX VIRUS IN CENTERAL ETHIOPIA
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Date
2018-06
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Abstract
A cross sectional observational study was conducted from September, 2017 to March,
2018 to outbreak investigation, isolation and molecular characterization of sheep and
goat pox virus in different districts of central Ethiopia. Study was engaged different
approaches especially questionnaire survey, virus isolation using vero cell line, classical
PCR for amplification of the DNA, gel-electrophoresis for identification of the specific
band, real time PCR for further genotyping, sequencing the RP030 gene for identification
of genetic relationship of sheep and goat pox virus isolate from field with other Capri
pox virus (CaPV).The questionnaire survey results indicated that sheep and goat pox was
the most common disease in all the study areas and the disease was frequently seen. The
disease outbreak more (52.94%) observed in rainy season. Additionally, non vaccinated
animals, female and young age shoats were more affected (P< 0.05) by pox virus. A total
of 712 sheep and goats (603 sheep and 109 goats) were clinically examined for the
presence of pox lesions on their skin and 35.82% sheep and 28.44% goats had pox
lesions. Generally, high mortality (9.95%) rate was observed in sheep than goats
respectively. The virus was isolated from 16 skin samples (13 sheep and 3 goats) and the
cell culture showed a typical characteristic of pox virus induced-cytopathic effect with
destruction of monolayer and rounding of the cell. Similarly, the conventional PCR
revealed that 16 out of 16 tested samples were positive by developing band size of 172bp
(Goat pox virus). Further more real time PCR 16 tested samples were positive for goat
pox virus with the melting temperature of (560C/72.50C). Phylogenetic tree analysis
revealed that the RP030 gene (606 nucleotides) sequences of the present isolates
originated from both sheep and goats were clustered with the goat pox virus group. Even
though the existing information suggested that capri pox virus is strictly host specific, but
in the current study the PCR and RP030 gene sequencing result confirmed that sheep
were infected by goat pox virus similarly to goat pox virus and hence classification of
pox virus based on infected host in small ruminant has been found to be inconclusive.
Description
A Thesis submitted to the College of Veterinary Medicine and Agriculture of Addis
Ababa University in partial fulfillment of the requirements for the degree of Master of
Science in Veterinary Microbiology
Keywords
Central Ethiopia, outbreak investigation, sheep and goat pox viruses