Phylogenetic analysis of three orf virus strains isolated from different districts in Shandong Province, East China

Molecular detection and phylogenetic analysis of Orf viruses from goats in Jiangxi province, China

Orf is a zoonosis caused by the Orf virus (ORFV), which is endemic in goats, sheep, and wild ruminants worldwide. Orf infection is prevalent in China, with outbreaks reported in several provinces. Currently, there is limited information available regarding the characterization of ORFV strains in Jiangxi province. This study investigated an acute outbreak of Orf that occurred in 2021 in a goat herd in the Jiangxi province of China. Clinical signs in this case included lesions on the lips, nose, and inside the mouth. The presence of ORFV was confirmed from tissue samples by polymerase chain reaction (PCR). The nucleotide sequences of the B2L and F1L genes were fully sequenced and used to construct phylogenetic trees. The results of this investigation identified the ORFV JXxy2021 as the cause of the outbreak. The phylogenetic analysis revealed that the ORFV strain JXxy2021 had the highest similarity to the ORFV strains GO and FJ-SL from the neighboring province of Fujian. This suggests that JXxy2021 was likely transmitted from Fujian province. The results have provided valuable information on the genetic characteristics of JXxy2021 and the endemic situations of Orf in China.

An evaluation of the ecological niche of Orf virus (Poxviridae): Challenges of distinguishing broad niches from no niches

Contagious ecthyma is a skin disease, caused by Orf virus, creating great economic threats to livestock farming worldwide. Zoonotic potential of this disease has gained recent attention owing to the re-emergence of disease in several parts of the world. Increased public health concern emphasizes the need for a predictive understanding of the geographic distributional potential of Orf virus. Here, we mapped the current distribution using occurrence records, and estimated the ecological niche in both geographical and environmental spaces. Twenty modeling experiments, resulting from two- and three-partition models, were performed to choose the candidate models that best represent the geographic distributional potential of Orf virus. For all of our models, it was possible to reject the null hypothesis of predictive performance no better than random expectations. However, statistical significance must be accompanied by sufficiently good predictive performance if a model is to be useful. In our case, omission of known distribution of the virus was noticed in all Maxent models, indicating inferior quality of our models. This conclusion was further confirmed by the independent final evaluation, using occurrence records sourced from the Centre for Agriculture and Bioscience International. Minimum volume ellipsoid (MVE) models indicated the broad range of environmental conditions under which Orf virus infections are found. The excluded climatic conditions from MVEs could not be considered as unsuitable owing to the broad distribution of Orf virus. These results suggest two possibilities: that the niche models fail to identify niche limits that constrain the virus, or that the virus has no detectable niche, as it can be found throughout the geographic distributions of its hosts. This potential limitation of component-based pathogen-only ENMs is discussed in detail.

Recombinant Orf virus induced antibody production against capsid protein of porcine circovirus type 3 in mice

The emerging worldwide distributed porcine circovirus type 3 (PCV3) infection poses a serious threat to swine herds. An important means of preventing and controlling PCV3 infection is the development of the vaccine, while, the inability to cultivate in vitro has become the biggest obstacle. Orf virus (ORFV), the prototypic member of the Parapoxviridae, has been proven to be a novel valid vaccine vector for preparing various candidate vaccines. Here, recombinant ORFV expressing capsid protein (Cap) of PCV3 was obtained and proved its favorable immunogenicity inducing antibody against Cap in BALB/c mice. Based on the enhanced green fluorescent protein (EGFP) as a selectable marker, the recombinant rORFVΔ132-PCV3Cap-EGFP was generated. Then, recombinant ORFV expressing Cap only, rORFVΔ132-PCV3Cap, was obtained based on rORFVΔ132-PCV3Cap-EGFP using a double homologous recombination method by screening single non-fluorescent virus plaque. Results of the western blot showed that the Cap can be detected in rORFVΔ132-PCV3Cap infected OFTu cells. The results of immune experiments in BALB/c mice indicated that a specific antibody against Cap of PCV3 in serum was induced by rORFVΔ132-PCV3Cap infection. The results presented here provide a candidate vaccine against PCV3 and a feasible technical platform for vaccine development based on ORFV.

Contagious ecthyma: how serious is the disease worldwide?

Contagious ecthyma (CE) is an infectious disease of small ruminants caused by a parapoxvirus of family Poxviridae subfamily Chordopoxvirinae. The disease is obviously distinguished by an establishment of scabby lesions and ulcerative formation on less hairy areas including muzzle, ears, nostril, and sometimes on genitalia. The disease is endemic in sheep and goats. The virus is transmissible to other ruminants and is a public health concern in humans. Although the disease is known as self-limiting, it may cause a significant economic threat and financial losses due to lower productivity in livestock production. Information with regard to the risk of the disease and epidemiology in most parts of the world is underreported. This paper aims to provide relevant information about the epidemiology of CE in selected regions of Europe, South America, North America, Asia, Africa, and Australia. An in-depth comprehension of virus infection, diagnoses, and management of the disease will enable farmers, researchers, veterinarians, abattoir workers, health personnel, and border controllers to improve their measures, skills, and effectiveness toward disease prevention and control, toward reducing unnecessary economic loss among farmers. A herd health program for significant improvement in management and productivity of livestock demands a well planned extension program that ought to encourage farmers to equip themselves with adequate skills for animal healthcare.

Laboratory Diagnosis of a NZ7-like Orf Virus Infection and Pathogen Genetic Characterization, Particularly in the VEGF Gene

Orf is a widespread contagious epithelial viral disease found particularly in most sheep breeding countries in the world. Recently, an orf virus (ORFV) strain OV-HLJ05 was isolated from an outbreak in northeast China. Three genes of interest including ORFV011 (B2L), ORFV059 (F1L), and ORFV132 (VEGF) of ORFV, were recruited to identify and genetically characterize this newly isolated virus. Amino acid (aa) sequence compared with the ORFV references listed in GenBank, both B2L and F1L of OV-HLJ05 showed less microheterogeneity from their references. In contrast, the VEGF gene was included in the NZ7-VEGF like group as previously considered by Mercer in 2002. Unexpectedly, further multiple VEGF matches were made, using 34 published sequences from China and India, resulting in 27 strains of the NZ7 members. Based on Karki's report in 2020, NZ7-VEGF like viruses are emerging more and more frequently in these two countries, damaging the Asian sheep industry. Obvious heterogeneity with the NZ2, insertion of two oligopeptides TATI(L)QVVVAI(L) and SSSS(S) motif were found in the NZ7-like VEGF protein. These VEGFs are divided mainly into two types and a significant increase in the number of hydrogen bonds within the NZ7-like VEGF dimers was observed. The NZ7-like ORFV apparently favors the goat as a host and an emphasis on this in future epidemiological and pathological studies should be considered, focusing on the NZ7-like virus.

Pathogenicity of blood orf virus isolates in the development of dairy goat contagious pustular dermatitis

Contagious pustular dermatitis is an exanthematous zoonotic disease caused by the orf virus. Pandemic outbreaks of this disease cause great economic losses, while the pathogenesis of this disease still remains obscure. In this study, blood samples were collected from 628 asymptomatic goats across China for PCR-based virus detection. We detected the orf virus in the blood of asymptomatic goats. Moreover, the orf virus obtained from the blood of infected goats was infectious and induced typical symptoms of contagious pustular dermatitis after inoculation of uninfected dairy goats. In summary, our data provide evidence that asymptomatic animals may be carriers of orf virus. Our findings should contribute to elucidating the details underlying the pathogenesis of contagious pustular dermatitis.

The whole genomic analysis of orf virus strain HN3/12 isolated from Henan province, central China

Background

The Orf virus (ORFV) is the causative agent of orf, a globally-occurring, acute, pustular, contagious disease affecting sheep, goats and humans with a worldwide distribution. Currently, the genomic analysis of four ORFV strains from the Fujian province in southern China and a NA1/11 strain isolated from the Jilin province in northeast China have been reported. However, little is known about the genomic information of ORFV strains from central China.

Results

From a recent outbreak in a sheep herd in the Henan province of central China, a novel ORFV strain (HN3/12) was isolated and cultured in ovine fetal turbinate (OFTu) cells. The strain was identified as HN3/12 and verified by PCR based on the DNA sequences of 011 and 059 genes. The whole genomic sequence of this isolate was determined by Next Generation Sequencing technology. To determine the genetic characteristics of the HN3/12 strain, phylogenetic analysis of the 011 and 059 genes and amino acid sequence alignment of the HN3/12 strain were performed and compared with reference parapoxvirus strains.

Conclusions

The HN3/12 genome is 136,643 bp in length, contains 63.67% G + C and encodes 132 putative genes. Phylogenetic analysis of the 011 and 059 nucleotide sequences showed that this viral strain was similar to the NA1/11 isolate. The homology analysis indicates that HN3/12 has 93% to 98% identity with published ORFV strains at amino acid level. When open reading frames (ORFs) were aligned among the HN3/12 and four Fujian ORFV strains, most of them have identities greater than 90% and only a few less than 60%. The availability of the whole genomic sequence of HN3/12 aids in our understanding of, and provides new insights into, the genetic diversity of ORFV.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-017-1178-1) contains supplementary material, which is available to authorized users.

Diagnosis and phylogenetic analysis of a multifocal cutaneous orf virus with mixed bacterial infection outbreak in goats in Fujian province, China

Outbreaks of orf virus on goat farms are common in China. In this study, we investigated a severe multifocal cutaneous orf virus outbreak with a correlative mixed bacterial infection which persisted for up to 6 months, and which had a high morbidity (93.7%) and mortality (15%) among kids in a herd of crossbreed goats in Fujian province in China. The disease was diagnosed as an orf virus (ORFV XD strain) infection associating with Streptococcus pluranimalium and Staphylococcus, identified using standard virological and bacteriological techniques. Multiple sequence alignments and phylogenetic analyses of the whole ORFV 011 (B2L), 059 (F1L), 032 and 080 genes revealed that the even though the virus phylogeny was clustered in branches of conventional orf virus strains, it nonetheless evidenced high variation within this subset. Furthermore, the sequences from the ORFV 080 gene allowed us to distinguish between the different strains at a higher resolution and these observations afforded us a comparative view of the ORFV 080 gene. This is the first report describing an outbreak of severe multifocal cutaneous orf virus with associated bacterial infection in China.