Phylogenetic analysis of strains of Orf virus isolated from two outbreaks of the disease in sheep in Greece

Charalambos Billinis,George C Fthenakis,Vasiliki Spyrou,Vasia S Mavrogianni

doi:10.1186/1743-422x-9-24

Charalambos Billinis, George C Fthenakis + Show 2 more

Open Access

https://doi.org/10.1186/1743-422x-9-24

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Abstract

BackgroundAlthough orf is endemic around the world, there are few descriptions of Orf virus strains and comparisons of these strains. We report the sequence and phylogenetic analysis of the partial B2L gene of Orf virus from two outbreaks of the disease in Greece. The first was an outbreak of genital form of the disease in a flock imported from France, whilst the second was an outbreak of the disease in the udder skin of ewes and around the mouth of lambs in an indigenous flock.ResultsPhylogenetic analysis was performed on a part (498 bp) of the B2L gene of 35 Parapoxvirus isolates, including the two Orf virus isolates recovered from each of the two outbreaks in the present study. This analysis revealed that the maximum nucleotide and amino-acid variation amongst Orf virus strains worldwide (n = 33) was 8.1% and 9.6%, respectively. The homology of the nucleotide and amino-acid sequences between the two Greek isolates was 99.0% and 98.8%, respectively. The two Greek isolates clustered only with Orf virus strains.ConclusionsWe suggest that there can be differences between strains based on their geographical origin. However, differences in the origin of strains or in the clinical presentation of the disease may not be associated with their pathogenicity. More work is required to determine if differing clinical presentations are linked to viral strain differences or if other factors, e.g., flock immunity, method of exposure or genetic susceptibility, are more important to determine the clinical presentation of the infection.

Highlights

Orf is endemic around the world, there are few descriptions of Orf virus strains and comparisons of these strains
Phylogenetic analysis was performed on a part (498 bp) of B2L gene 35 Parapoxvirus strains, including the two strains recovered in the present study
Animals from the flock infected with the ‘GRE-2 teat 2004’ strain were subsequently used in an experimental study, where it was shown that Orf virus infection in teats of ewes leads to depletion of local mammary defences and predisposes animals to mastitis [24]

Summary

Introduction

Orf is endemic around the world, there are few descriptions of Orf virus strains and comparisons of these strains. We report the sequence and phylogenetic analysis of the partial B2L gene of Orf virus from two outbreaks of the disease in Greece. Contagious echtyma (’orf’) is a contagious disease, caused by the epitheliotropic Orf virus, a member of the genus Parapoxvirus. The disease has a worldwide distribution and a significant financial importance. The disease affects primarily sheep and goats; camels, South American camelids, Cervidae (deer, reindeer), other ruminants (bighorn sheep, chamois, dall sheep, mountain goats, musk oxen, serows, steenboks, tahr), dogs, cats and squirrels. The disease has a zoonotic potential, it is more of an occupational hazard to people working with animals (e.g., farmers, animal carers, veterinarians).

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