Molecular Insights into the Genetic Variability of ORF Virus in a Mediterranean Region (Sardinia, Italy)

Abstract

Orf virus (ORFV) represents the causative agent of contagious ecthyma, clinically characterized by mild papular and pustular to severe proliferative lesions, mainly occurring in sheep and goats. In order to provide hints on the evolutionary history of this virus, we carried out a study aimed to assess the genetic variation of ORFV in Sardinia that hosts a large affected small ruminant population. We also found a high worldwide mutational viral evolutionary rate, which resulted, in turn, higher than the rate we detected for the strains isolated in Sardinia. In addition, a well-supported genetic divergence was found between the viral strains isolated from sheep and those from goats, but no relevant connection was evidenced between the severity of lesions produced by ORFV and specific polymorphic patterns in the two species of hosts. Such a finding suggests that ORFV infection-related lesions are not necessarily linked to the expression of one of the three genes here analyzed and could rather be the effect of the expression of other genes or rather represents a multifactorial character.

A Deeper Insight into Evolutionary Patterns and Phylogenetic History of ORF Virus through the Whole Genome Sequencing of the First Italian Strains

“…The strains that have differentiated in the 21st century may be exclusive to the island, specifically the northern area. Another point of interest is that the molecular dating provided by the present research for the common ancestor of the ORFV genome strains isolated from sheep in Sardinia (year 1950) is quite consistent with the estimation reported by Coradduzza et al [22] based on the ORFV VIR gene (year 1925). The small discrepancy could be related to the different molecular datasets used to perform molecular dating (whole genome 137,151 bp vs. VIR gene 382 bp).…”

“…Furthermore, the evolutionary mean rate calculated for the ORFV type G genomes was similar to the value obtained in the present study when the strains from all hosts (goats, sheep and humans) were considered together. However, the evolutionary mean rate calculated for the ORFV type S genomes was higher and more similar to the value obtained by Coradduzza et al [22] for the ORFV VIR gene which was isolated in hosts from all continents. This latter finding suggests a possible connection (that must be supported by further specific genetic studies) between the occurrence of contagious ecthyma in sheep and the expression of the gene encoding the dsRNA-binding protein in the viral strains that infect these animals.…”

“…Clinical CE-outbreaks have been detected and reported by private practitioners and veterinary public health components involved in the present research, during their diagnostic activity. Sampling collection protocols were as reported by Coradduzza et al, 2021 [ 22 ]. Viral DNA was extracted from lesions isolated in five infected sheep and two infected goats (see Table 1 for details on the samples).…”

“…A similar phylogenetic deep inference was previously performed for samples from all over the world based on the ORFV gene, encoding the dsRNA-binding protein ( VIR ) [ 22 ]. Results evidenced a high worldwide mutational viral evolutionary rate, along with a well-supported genetic divergence between the viral strains isolated from sheep and those from goats.…”

Evolutionary and Conservation Genetics

“…), not only (and not anymore) for the mere appreciation of biodiversity, but also to provide a support for the management and conservation of endangered species or species deemed potentially dangerous to the human health. Therefore, this Special Issue aimed to combine the contributions of researchers working globally in the field of evolutionary genetics/biology, population genetics, molecular taxonomy, and conservation genetics, in order to obtain a bulk of papers that underscore the importance of studying genetic variability in organisms for safeguarding biodiversity, in all ways it can be understood [4][5][6][7][8][9][10][11].…”