Conventional and Molecular Characterization of Sheep Poxvirus (SPV) in Dakahlia Governorate, Egypt

Abstract

Objective: Isolation, conventional and molecular characterization of sheep poxvirus (SPV) from clinically diseased vaccinated sheep in  Dakahlia Governorate, Egypt.
Design: Descriptive study.
Samples: Forty samples including 20 skin nodules and 20 from lung, liver, lymph node and tongue (5samples from each) were collected  from sheep flock consisted of 25 adult and 5 lambs.
Procedures: The suspected virus was isolated through embryonated chicken eggs (ECEs). SPV was detected by agar gel precipitation test  (AGPT), indirect fluorescence antibody test (IFAT) and histopathology in field and egg passaged samples. Ten samples were selected for  molecular characterization by conventional and real time polymerase chain reaction (PCR) and for sequence analysis based on P32 gene.
Results: The disease prevalence was 16.7% (5 infected). Thirty-two samples (80%) recorded positive isolation of SPV (skin nodules, n=16;  lung, n=5; lymph node, n=5; liver, n=3; tongue, n=3). The positive results percentage for AGPT and IFAT in field samples was 42.5% and  92.5%, respectively. In egg passaged samples, 82.5% of samples showed positivity by IFAT. Intra- cytoplasmic inclusions were detected in  75% of field samples, and in 62.5% of egg passaged samples. All selected samples for the virus molecular detection showed positive  results. P32 gene sequence analysis revealed that our SPV was closely related to Saudi Arabia virus, 2019.
Conclusion and clinical relevance: SPV detected from clinically diseased vaccinated sheep in Egypt. So further study is crucial to identify  the reason for vaccination failure  and also on precise determination of this virus origin as well as virus spread pattern analyses.