Detection and phylogenetic analysis of Orf virus in Kashmir Himalayas

Detection and Phylogenetic Analysis of Orf Virus and Muskox Rhadinovirus 1 from Muskoxen (Ovibos moschatus) in the Canadian Arctic

Orf virus (genus Parapoxvirus) has been associated with gross skin lesions on muskoxen (Ovibos moschatus) from Victoria Island, Nunavut, Canada, where muskox populations are experiencing population declines. Orf virus causes painful proliferative and necrotizing dermatitis upon viral replication and shedding, which may lead to animal morbidity or mortality through secondary infections and starvation. Herpesvirus, known to cause gross lesions on skin and mucosa during active viral replication, has also been documented in muskoxen but to date has not been associated with clinical disease. Our objective was to characterize the variation of orf virus and herpesvirus in wild muskoxen of the Canadian Arctic. Tissue samples including gross skin lesions from the nose, lips, and/or legs were opportunistically collected from muskoxen on Victoria Island, Nunavut and Northwest Territories, and mainland Nunavut, Canada, from 2015 to 2017. Sampled muskoxen varied in age, sex, location, hunt type, and body condition. Tissues from 60 muskoxen were tested for genetic evidence of orf virus and herpesvirus infection using PCR targeting key viral genes. Tissues from 38 muskoxen, including 15 with gross lesions, were also examined for histological evidence of orf virus and herpesvirus infection. Eleven muskoxen (10 from Victoria Island and one from mainland Nunavut) with gross lesions had microscopic lesions consistent with orf virus infection. Muskox rhadinovirus 1, a gammaherpesvirus endemic to muskoxen, was detected in 33 (55%) muskoxen including 17 with gross lesions. In all tissues examined, there was no histological evidence of herpesvirus-specific disease. Sequencing and characterization of amplified PCR products using phylogenetic analysis indicated that a strain of orf virus, which appears to be unique, is likely to be endemic in muskoxen from Victoria Island and mainland Nunavut. Many of the muskoxen are also subclinically infected with a known muskox-endemic strain of herpesvirus.

The Global Evolutionary History of Orf Virus in Sheep and Goats Revealed by Whole Genomes Data

Orf virus (ORFV) belongs to the genus Parapoxvirus (Poxviridae family). It is the causative agent of contagious ecthyma (CE) that is an economically detrimental disease affecting small ruminants globally. Contagious ecthyma outbreaks are usually reported in intensive breeding of sheep and goats but they have also been reported in wildlife species. Notably, ORFV can infect humans, leading to a zoonotic disease. This study aims to elucidate the global evolutionary history of ORFV genomes in sheep and goats, including the first genomes from Central America in the analyses. In comparison to the last study on ORFV whole genomes, the database now includes 11 more sheep and goat genomes, representing an increase of 42%. The analysis of such a broader database made it possible to obtain a fine molecular dating of the coalescent time for ORFV S and G genomes, further highlighting the genetic structuring between sheep and goat genomes and corroborating their emergence in the latter half of 20th century.

Genetic Analysis of Orf Virus (ORFV) Strains Isolated from Goats in China: Insights into Epidemiological Characteristics and Evolutionary Patterns

Contagious ecthyma (CE) is an acute infectious zoonosis caused by orf virus (ORFV) that mainly infects sheep and goats and causes obvious lesions and low market value of livestock, resulting in huge economic losses for farmers. In this study, two strains of ORFV were isolated from Shaanxi Province and Yunnan Province in China, named FX and LX. The two ORFVs were located in the major clades of domestic strains respectively, and exhibited distinct sequence homology. We analyzed the genetic data of core genes (B2L, F1L, VIR, ORF109) and variable genes (GIF, ORF125 and vIL-10) of ORFV to investigate its epidemiological and evolutionary characteristics. The sequences from 2007 to 2018 constituted the majority of the viral population, predominantly concentrated in India and China. Most genes were clustered into SA00-like type and IA82-like type, and the hotspots in East and South Asia were identified in the ORFV transmission trajectories. For these genes, VIR had the highest substitution rate of 4.85 × 10-4, both VIR and vIL-10 suffered the positive selection pressure during ORFV evolution. Many motifs associated with viral survival were distributed among ORFVs. In addition, some possible viral epitopes have been predicted, which still require validation in vivo and in vitro. This work gives more insight into the prevalence and phylogenetic relationships of existing orf viruses and facilitate better vaccine design.

Epidemiology, clinical features, and molecular detection of orf virus in Haryana (India) and its adjoining areas

Orf is an acute, highly contagious, and economically important viral disease of small ruminants. In this study, six orf suspected outbreaks among goats and sheep were investigated from Haryana state and adjoining areas of Rajasthan state during the year 2021. The disease was diagnosed on the basis of clinical signs and molecular identification. The causative agent of the disease, orf virus (ORFV), was confirmed using polymerase chain reaction (PCR) targeting immunodominant envelope antigen (B2L) gene and confirmed by sequencing. The morbidity in goats ranged from 8.75 to 100%, whereas in sheep, it ranged from 0 to 8%. The higher mortality was observed among flocks with mixed infections of orf and peste des petits (PPR) or orf and haemonchosis as compared to other outbreaks. The phylogenetic analysis of sequenced PCR products clustered the current study strains in the same clad with Indian as well as strains from other countries with nucleotide identity more than 99%, signifying a close genetic relationship. The study highlighted the circulation of strains of a single cluster among sheep and goats in Haryana and adjoining areas. Prompt diagnosis of the disease is highly important for facilitating the implementation of control measures to minimize the losses suffered by small and marginal farmers in this region. Further detailed studies are required to delineate the molecular details of ORFV for better understanding the dynamics and molecular epidemiology of strains circulating in the country and for designing the effective vaccines against the disease which are currently lacking in the country.

Genomic Features and Evolution of the Parapoxvirus during the Past Two Decades

Parapoxvirus (PPV) has been identified in some mammals and poses a great threat to both the livestock production and public health. However, the prevalence and evolution of this virus are still not fully understood. Here, we performed an in silico analysis to investigate the genomic features and evolution of PPVs. We noticed that although there were significant differences of GC contents between orf virus (ORFV) and other three species of PPVs, all PPVs showed almost identical nucleotide bias, that is GC richness. The structural analysis of PPV genomes showed the divergence of different PPV species, which may be due to the specific adaptation to their natural hosts. Additionally, we estimated the phylogenetic diversity of seven different genes of PPV. According to all available sequences, our results suggested that during 2010-2018, ORFV was the dominant virus species under the selective pressure of the optimal gene patterns. Furthermore, we found the substitution rates ranged from 3.56 × 10-5 to 4.21 × 10-4 in different PPV segments, and the PPV VIR gene evolved at the highest substitution rate. In these seven protein-coding regions, purifying selection was the major evolutionary pressure, while the GIF and VIR genes suffered the greatest positive selection pressure. These results may provide useful knowledge on the virus genetic evolution from a new perspective which could help to create prevention and control strategies.

Identification of strain diversity and phylogenetic analysis based on two major essential proteins of Orf viruses isolated from several clinical cases reported in Malaysia

There is a little information on the characterization of Orf virus strains that are endemic in Malaysia. The relationship between the severity of disease and the molecular genetic profile of Orf virus strains has not been fully elucidated. This study documented the first confirmed report of contagious ecthyma causing by Orf virus in goats from a selected state of eastern peninsular Malaysia. The disease causes significant debilitation due to the inability of affected animals to suckle which brings a great economic loss to the farmers. A total of 504 animals were examined individually to recognize the affected animals with Orf lesion. Skin scrapping was used to collect the scab material from the infected animals. The presence of Orf virus was confirmed by combination of methods including virus isolation on vero cells, identification by Transmission Electron Microscopy (TEM) and molecular technique using PCR and Sanger sequencing. The results showed the successful isolation of four Orf virus strains with a typical cytopathic effects on the cultured vero cells line. The morphology was confirmed to be Orf virus with a distinctive ovoid and criss cross structure. The phylogenetic analysis revealed that these isolated strains were closely related to each other and to other previously isolated Malaysian orf viruses. In addition these Orf virus strains were closely related to Orf viruses from China and India. This study provides more valuable insight in terms of genotype of Orf virus circulating in Malaysia.

Molecular characterization of Orf virus isolates from Kodai hills, Tamil Nadu, India

Aim:

The present study was carried out to find out the causative agent of exanthematous skin lesions in sheep maintained by Southern Regional Research Centre, Mannavanur, Kodai hills, Tamil Nadu.

Materials and Methods:

Polymerase chain reaction (PCR) with Orf virus (ORFV) B2L gene-specific primers was carried out by employing the total genomic DNA isolated from the scabs as the template. The ORFV isolates from Kodai hills were characterized by the use of bioinformatics tools.

Results:

The amino acid identity of ORFV isolate 1 from Kodai hills is having 98.14%, 96.29%, and 83.59% identity with reference strains of ORFV, Pseudocowpox virus, and bovine papular stomatitis virus, respectively. Phylogenetic analysis revealed that ORFV isolates from Kodai hills clustered with the other ORFV isolates from different geographical areas of India.

Conclusion:

The etiological agent of exanthematous skin lesion among sheep of Kodai hills is ORFV.

TaqMan-based real-time quantitative fluorescence PCR for detection of Orf virus

Contagious ecthyma, also known as scabby mouth or Orf, is a zoonosis, which is caused by the Orf virus (ORFV). Human contact with infected animals can cause cutaneous lesions. To prevent and control ORFV effectively, rapid detection method is very important and highly needed. Real-time quantitative fluorescence PCR (qPCR) assay is considered as a rapid techonology to detect ORFV, and has been used for clinical diagnosis and epidemiological investigation. In present study, we developed a TaqMan-based qPCR assay for detection of ORFV. Beacon Designer 7.9 was used to design specific primers and probes were based on the ORFV020 gene sequence of the virus (GenBank Accession No. KF666563.1). The method had no cross-reactions with other common bacteria and viruses, was highly specific; the sensitivity test result showed that it could detect 10 copies of ORFV genomic DNA, and was more sensitive than conventional PCR. Both intra- and inter-variabilities were less than 2%, indicating the high stability and repeatability of the method. Additionally, 99 clinical samples from sheep and goats with suspected contagious ecthyma were tested using the developed assay and conventional PCR. The results showed that the developed assay was more sensitive and faster than conventional PCR. It can be concluded that the assay was suitable for routine detection of the ORFV and the epidemiological investigation.