Comparative sequence analysis of poxvirus A32 gene encoded ATPase protein and carboxyl terminal heterogeneity of Indian orf viruses

Abstract

Thirteen orf virus (ORFV) isolates from natural outbreaks in sheep and goats belonging to different geographical regions of India were analysed on the basis of ORF108 (a homologue of poxviral A32 gene), which is known to encode for ATPase and involved in virion DNA packaging. Comparative sequence analysis of ATPase proteins revealed highly conserved N-terminal region with five different motifs [Walker A, Walker B, A32L specific motifs (III and IV) and a novel AYDG (motif-V)] among all poxviruses and divergent carboxyl terminus with either single or double RGD sequences among all Indian ORFV isolates. A homology model and secondary structure predictions of N-terminal region of ORFV A32 revealed that most of the poxviruses including ORFV ATPase protein belong to a distinct clade of the HerA/FtsK super family of DNA packaging proteins. Despite differences in host cell specificity and poxvirus infections among animals, DNA packaging motor domain of poxviruses presumed to share remarkable similarities as indicated by the presence of conserved ATPase motifs in the present investigation. The study also indicated the circulation of heterogenous strains of ORFV in India and possibilities of differentiation of ORFV strains based on C-terminal heterogeneity.