Abstract:
Orf virus (ORFV) is a member of the parapoxvirus genus that causes orf, a zoonotic and
epitheliotropic highly contagious disease mainly affecting sheep, goats, wild ruminants
and humans. In the present study, an outbreak of a disease in goats with clinical signs
suggestive of orf in 11 flocks with a total of 259 goats was investigated between May and
June 2015. Eight villages in districts of Bagamoyo (2), Ilala (1), Kinondoni (1) and
Kisarawe (4) in Coast and Dar es Salaam regions of Tanzania were involved. The aim of
the present study was to confirm ORFV involvement in diseased goats and to provide the
genetic characteristics of ORFV. Upon visiting of goat flocks, a total of 72 goats presented
orf-like clinical signs and 24 were reported to have died with similar clinical presentation.
The presence of ORFV in oral swabs, scabs and skin scrapings was investigated by partial
amplification of the ORFV RNA polymerase gene using Orf1 and Orf2 primers by
polymerase chain reaction (PCR). A total of 16 out of 22 goats tested positive for ORFV
upon PCR. Afterwards, molecular characterisation of ORFV was performed by
amplification and nucleotide sequencing of the B2L gene encoding the major envelope
protein. The results of nucleotide sequencing showed that orf was caused by closely
related ORFV belonging to cluster I. ORFV were found to be genetically closely related to
OV-SA00 (Accession number AY386264) strain of ORFV isolated in 2003 from scab
material of a kid in United States of America and ORFV collected from a goat in Kyela,
Tanzania in 2013. To our knowledge, this is the first report of the phylogenetic analysis of
B2L gene of ORFV from goats in Tanzania. More studies are required to determine the
extent of spread and genetic diversity of ORFV in livestock, wildlife and humans.
