Orf (ORF) is an acute disease caused by the Orf virus (ORFV), and poses a certain threat to animal and human health. Live attenuated vaccines play an important role in the prevention and control of ORF. The effectiveness of the live attenuated Orf virus vaccine is influenced by several factors, including the genomic match between the vaccine strain and circulating epidemic strains. Genomic differences between an ORFV epidemic strain (ORFV-2W) and a vaccine strain (ORFV-1V) were identified in this study via analysis of multiple sequence alignments, phylogenetic trees, and single nucleotide polymorphisms. Phylogenetic analysis revealed that ORFV-2W and ORFV-1V were closely related, with a whole genome homology of 99.8%. Furthermore, a deletion in the non-coding region at the end of the whole genome of ORFV-1V was detected. Such non-essential genes in the terminal regions are usually unnecessary for virus replication but may play important roles in pathogenicity, host and tissue tropism. Single nucleotide polymorphism analysis identified three missense mutations in ORF067, ORF072, and the terminal non-coding region of ORFV-1V. Moreover, a frameshift mutation in ORF102 of ORFV-1V was detected. Mutations in individual genes and deletion of terminal non-coding regions may be related to the attenuation of the vaccine strain. These results provide useful context for improving ORFV vaccines.

Akabane virus (AKAV) causes abortion, stillbirth, and congenital malformations in ruminants, yet the transcriptional response of Madin–Darby bovine kidney (MDBK) cells and the roles of infection-responsive host genes in AKAV replication remain incompletely characterized. We profiled AKAV-infected and time-matched mock-infected MDBK cells by RNA sequencing at 12 and 24 h post-infection (hpi). Differentially expressed genes (DEGs) were examined using Gene Ontology functional classification and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis, six DEGs were evaluated by RT-qPCR, and OAS2 and ZBP1 were assessed by overexpression in BHK-21 cells. We identified 119 DEGs at 12 hpi (82 upregulated and 37 downregulated) and 149 at 24 hpi (85 upregulated and 64 downregulated). The DEG sets were associated with antiviral defense, interferon responses, pattern recognition receptor signaling, DNA replication, cell cycle regulation, chromosome organization, and metabolism. RT-qPCR measurements were consistent with the RNA-seq trends. OAS2 and ZBP1 transcripts were significantly upregulated at 12 hpi, while ZBP1 transcript levels remained significantly elevated at 24 hpi. Overexpression of either gene was associated with reductions in AKAV Gc protein abundance, viral RNA levels, and infectious titers. These results define transcriptional changes in AKAV-infected MDBK cells and nominate OAS2 and ZBP1 as candidate host factors for further investigation, while their endogenous roles in bovine cells remain to be established.