Molecular characterizations Of Iranian sheeppox and goatpox viruses by sequence analysis of chemokine receptor homologue gene.

Capripoxvirus (CaPV) genus of Poxviridae family comprises three closely related viruses, namely goat poxvirus (GPV), sheep poxvirus (SPV) and lumpy skin disease virus (LSDV). Sheep and goat pox along with contagious ecthyma (CE) genus of parapoxvirus are endemic diseases in Iran. Because of close antigenic relationship between CaPV and Parapoxvirus, virological and serological differentiative studies are not enough suitable. Furthermore, CaPVs are serologically identical and their specific identification relies exclusively on the use of molecular tools. The aim of this study was molecular characterization of Iranian SPV and GPV (SGPVs) based on the chemokine receptor (CKR) hemologue gene. At first a capripoxvirus specific PCR assay was developed based on the 390 bp fragment of P32 gene to identify SGPVs. This PCR was carried out on Twenty-five positive biopsy samples from different organs of sheep and goats suspected to SGPVs against six infected with CE. Twenty-five samples were positive and all samples of CE were negative. In order to characterize CKR hemologue gene of Iranian SGPVs, ten isolates of SGPVs from positive biopsy samples were used. A PCR assay was developed by designing specific primers for CKR hemologue gene. PCR products were inserted to pTZ57R/T vector. Then, obtained fragments were sequenced and analysed. They were compared to the other CKR sequences of CaPVs available in the database. Iranian SPV isolates showed more than 99% identity with SPVs in databases, except for Oman SPV and Kenya SPV (KS-1 strain). Iranian GPV isolates have 98-99% identity with GPVs in databases, except for Saudi Arabia, Sudan and Nigeria GPV isolates. The Gorgan GPV isolate with Turkey, Kasakhstan, Iraq, Yemen and African GPV strains, and other four Iranian GPV isolates with India and Bangladesh GPV isolates have the same gene profile. A PCR-RFLP technique by designing specific primers for 676 bp fragment of CKR hemologue gene was developed for differentiating SPV and GPV. Restriction enzyme site profiling of the fragment was carried out by using DNAMAN software. The Mun I (Mfe I) and Bst BI (Bsp 119 I) enzume were specifically designated for SPV and GPV, respectively. The fragment of CKR gene for ten Iranian SGPVs, along with vaccinal SGPV strains, Kenya sheeppox 0240 and LSDV Neethling strains were amplified. The amplicons of SGPVs showed two different patherns in gel electrophoresis after enzyme digestion. In contrast, Kenya sheeppox 0240 and LSDV Neethling strains have no enzymatic digestion pathern. Conclusively, the CKR hemologue gene is a suitable target for describing genetic diversity of CaPVs and discrimination of Iranian SPVs and GPVs. The present PCR-RFLP basis on this gene has considarable potential for identifying species origin of CaPVs. Therefore, this PCR-RFLP is suggested as a molecular tool for further epidemiological studies.