Abstract
Abstract
Background: Orf is a highly contagious viral skin disease in sheep and goats caused by Orf virus (ORFV) in genus Parapoxvirus. Although sheep and goats are considered a basic food resource, particularly in Africa, Orf virus infection represents an increasing challenge to animal productivity causing high economic losses.
Aim: Therefore, this study aimed to detect and characterize Orf virus in suspected clinically diseased goats in two neighboring Egyptian governorates, Al-Sharkia and Ismailia, flocks during the months of April 2020 and July 2021by using PCR and phylogenetic analysis of partial B2L sequence.
Methods: Young aged kids from two Egyptian governorates showed the clinical picture of ORFV infection, Samples were collected (n = 15) from two different flocks in April 2020 and July 2021. PCR was carried out for detection of Orf virus by targeting a highly conserved sequence within ORFV (B2L) gene. To determine the phylogenetic relationship with other ORFV strains, sequencing and phylogenetic analysis were performed.
Results: ORFV infection was confirmed in 12 samples of oral scabs (80%) by PCR targeting a highly conserved sequence within B2L gene. Sequencing of DNA products was performed and obtained sequences revealed 100% identity at nucleotide level. Isolates of this study showed 98.2% nucleotide identity with a previous Egyptian ORF virus (KP984529) whereas our isolates showed higher nucleotide identities, 99.1% and 98.7% with ORFV strains from neighboring countries, Sudan and Ethiopia, respectively. The phylogenetic tree grouped isolates into two main clusters, Cluster I included isolates of this study and foreign ones mainly from China, India, and Sudan. Interestingly, the vaccine strains of ORF used in different countries were grouped in another cluster with previous Egyptian isolate (KP984529), Ethiopian and Israeli ORFV isolates.
Conclusion: Molecular characterization of B2L gene of ORFV isolates revealed higher sequence identities and more close genetic relationships with other ORFV strains circulating in neighboring countries than with the Egyptian isolates. These findings may provide an insight into genetic diversity of field ORFV isolates circulating in goats in the Egyptian governorates.

Key words: Egypt, Orf virus, Goat, B2L gene, PCR.