Orf: an update on current research and future perspectives

Use of a local anaesthetic and antiseptic wound formulation for the treatment of lambs naturally infected with Orf virus

Contagious ecthyma (CE) is a worldwide highly contagious zoonotic viral skin disease of sheep and goats. Treatment for Orf virus (ORFV) infection usually involves topical and oral antibiotics. An anaesthetic and antiseptic topical gel (Multisolfen® or Tri-Solfen®; MS®, Medical Ethics, Australia) has been documented as an efficacious therapy for lesions from mucosal and epithelial viral infections in ruminants. The present study tested a new treatment protocol of MS® for CE therapy on-farm in 150 lambs naturally infected with ORFV. Lambs were divided into three cohorts of 50 lambs each (C, D and E). Cohort C was treated with MS® 3 times with an interval of 3 days between treatments, cohort D was treated daily with hypochlorous acid, whilst cohort E served as untreated controls. The lambs were examined clinically every two days, weight measured weekly, with whole blood and sterile swabs from ORFV lesions collected for haematological analysis and specific ORFV PCR. Cohort C presented fewer lambs displaying ORFV-associated lesions than other cohorts at different times of the experiment. Further, lesions treated with MS® were milder compared with other cohorts. However, following cessation of therapy, most of the lambs again developed ORFV-associated lesions. No differences between cohorts were observed in weight, haematological and PCR results. These findings suggest that topical treatment with MS® is effective for CE in field conditions, especially in the first stages of the clinical course, although treatment with MS® may need to be extended a minimum of 4 weeks.

Tracing the journey of poxviruses: insights from history

The historical significance of the poxviruses is profound, largely due to the enduring impact left by smallpox virus across many centuries. The elimination of smallpox is a remarkable accomplishment in the history of science and medicine, with centuries of devoted efforts resulting in the development and widespread administration of smallpox vaccines. This review provides insight into the pivotal historical events involving medically significant poxviruses. Understanding the remarkable saga of combatting smallpox is crucial, serving as a guidepost for potential future encounters with poxvirus infections. There is a continual need for vigilant observation of poxvirus evolution and spillover from animals to humans, considering the expansive range of susceptible hosts. The recent occurrence of monkeypox cases in non-endemic countries stands as a stark reminder of the ease with which infections can be disseminated through international travel and trade. This backdrop encourages introspection about our journey and the current status of poxvirus research.

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.

Finger nodules with a papulovesicular hands and feet eruption: a complicated human Orf virus infection

BACKGROUND

Orf virus (ORFV) is the pathogen responsible for Orf, a zoonotic viral infection that can be spread to humans from sheep and goats. Here, we present a case of human Orf complicated by an immune-related reaction, to raise awareness of this under-recognized disease avoiding unnecessary investigations and overtreatment.

CASE REPORT

A 51-year-old woman with no previous medical history presented with a one-week history of three asymptomatic swelling nodules with a grey necrotic center and red outer halo on her index finger. At physical examination there was also a pruritic papulovesicular eruption on her hands and feet. She reported a recent contact with a goat which had a similar nodular lesion in its mouth. A biopsy of the lesions was performed and a diagnosis of Orf complicated by widespread erythema multiforme was made based on the clinical and histopathological features. The lesions spontaneously resolved within the next 2 weeks.

CONCLUSIONS

Orf is not very prevalent in our region, so we performed a biopsy of the lesion to guide us toward a diagnosis. However, we should remember that the diagnosis of ecthyma relies on clinical evaluation and epidemiological criteria.

The cooperation between orf virus and Staphylococcus aureus leads to intractable lesions in skin infection

A large amount of evidence shows that different kinds of microorganisms can jointly cope with environmental pressures including cell hosts. For example, in many cases, it has been found that secondary or mixed infection of animals caused by ORFV (an epitheliophilic Parapoxvirus) and bacteria (such as Staphylococcus aureus or Streptococcus) shows a mutual aid mode that indirectly leads to the deterioration of the disease. However, the lack of research on the co-pathogenic mechanism, including how to hijack and destroy the cell host in the pathological microenvironment, has hindered the in-depth understanding of the pathogenic process and consequences of this complex infection and the development of clinical treatment methods. Here, we summarized the current strategies of trapping cell hosts together, based on the previously defined ORFV-Host (O-H) system. The opportunistic invasion of S. aureus destroyed the delicate dynamic balance of the O-H, thus aggravating tissue damage through bacterial products (mediated by Agr), even causing sepsis or inducing cytokine storms. In fact, the virus products from its adaptive regulatory system (VARS) weaken the immune attacks and block molecular pathways, so that S. aureus can settle there more smoothly, and the toxins can penetrate into local tissues more quickly. This paper focuses on the main challenges faced by cell hosts in dealing with mixed infection, which provides a starting point for us to deal with this disease in the future.

Contagious ecthyma in Egypt: Clinical, virological and molecular explorations

Contagious Ecthyma (CE) is a highly contagious viral disease of sheep and goats with worldwide distribution. The present study aimed to provide a clinical description of contagious ecthyma in four sheep flocks and screen the possible genetic variation in the B2L gene of the detected isolates. Oral lesions were collected and inoculated into chorioallantoic membrane (CAM) of 11 days embryonated chicken eggs. Polymerase chain reaction and direct sequencing of the B2L gene was conducted. Infected sheep exhibited anorexia with a development of nodular lesions evolving in proliferative thick scabs around oral commissures. The inoculated CAM showed small-sized white pock lesions accompanied with thickening of CAM. The partial length of B2L gene (592 bp) was successfully amplified in samples collected from four flocks. The isolated strains belong to genotype I/I and I/II. Sequence and evolutionary analysis illustrate that B2L gene (ORF011) are highly conserved among Orf viruses isolated from different countries.

Dual analysis of wild-type and attenuated Orf virus and host cell transcriptomes revealed novel virus-host cell interactions

IMPORTANCE

Currently, the only available commercial vaccines for Orf virus (ORFV) are live attenuated vaccines, which present a potential risk of reversion to virulence. Therefore, understanding the pathogenic mechanisms of different virulent strains of ORFV and host immune responses triggered by these viruses is crucial for developing new vaccines and interventions. In this study, we found that the attenuated strain downregulates the host innate immune response and antiviral activity. In addition, we noted that the wild-type strain can induce the immune response pattern centered on interferon-stimulated genes and interferon regulatory factor gene family. We predicted that STAT1 and STAT2 are the main transcription factors upstream of target gene promoters through gene regulatory networks and exert significant regulatory effects on co-expressed genes. Our study elucidated the complex interaction between ORFV strains and host cell immune responses, providing new insights into vaccine research for ORFV.

Use of a Local Anaesthetic/Antiseptic Formulation for the Treatment of Lambs Experimentally Infected with Orf Virus

Contagious ecthyma is a highly transmissible eruptive viral disease of the skin and mucosa of sheep and goats distributed worldwide. The treatment of orf lesions is usually based on the use of antiseptics and antibiotics for the management of presumptive secondary infections, increasing risks of antimicrobial resistance. The wound dressing formulation Tri-Solfen® (TS) containing two local anaesthetics (lignocaine and bupivacaine), adrenaline and an antiseptic (cetrimide) in a gel formulation has been demonstrated to reduce suffering and enhance recovery in cattle and buffalo with oral and skin lesions due to foot-and-mouth disease virus infection and reduced the orf viral load in lambs. In the present study, experimental infection with the orf virus was conducted in 50 newborn lambs and 25 animals were treated after the presence of the first lesions with TS and repeated three days later. Daily clinical examination, haematological, serological, biomolecular and post-mortem analyses were conducted during 34 days after treatment. Results indicated that treatment had no effect on weight gain and clinical progression of the lesions. It was determined that seroconversion after experimental infection occurs 34 days after infection and suggested that the deep basal epithelial location of the orf lesions may have prevented the therapy from having altered the clinical course.

Host range, severity and trans boundary transmission of Orf virus (ORFV)

Contagious ecthyma in small ruminants is a zoonotic disease caused by Orf virus (ORFV) in the genus Parapoxvirus that can be deadly to its natural hosts. It causes significant losses worldwide, and commonly infects humans. However, the literature about its comparative severity in sheep and goat hosts is misleading; and while contagious ecthyma has been shown to occur in camels and transmit to humans, there is confusion as to whether ORFV is responsible. Camels are important from a 'One Health' perspective as they have been implicated as a reservoir host for the virus causing Middle East Respiratory Syndrome (MERS), which has a case fatality rate of 35% in humans. We compared ORFV gene sequences and mortality data from the West Bank in Palestine, where ORFV has not been reported previously, with data from the region. Surprisingly, we found that infections of camels that had been attributed to ORFV were more closely related to a different member of the genus Parapoxvirus. Two Middle East ORFVs isolated from humans were unrelated and sat alongside sheep and goat derived sequences on two distinct ORFV lineages of a maximum likelihood B2L gene tree. One of the viral lineages bifurcated to produce a monophyletic group of goat-derived ORFVs characterized uniquely by a glycine at amino acid reside 249. We found that serine is the ancestral allele shared between ORFV infections of sheep and also two closely related Parapoxviruses (PCPV and CCEV), indicating that the glycine allele represents a more recent shift in virus host range adaptation to goats. Furthermore, and contrary to some reports that ORFV is more severe in goats than in sheep, we observed median mortality of up to 24.5% in sheep, but none in goats. We also identified trans-boundary spread of ORFV between the West Bank and Israel.

Construction of a Triple-Gene Deletion Mutant of Orf Virus and Evaluation of Its Safety, Immunogenicity and Protective Efficacy

Contagious ecthyma is a zoonotic disease caused by the orf virus (ORFV). Since there is no specific therapeutic drug available, vaccine immunization is the main tool to prevent and control the disease. Previously, we have reported the construction of a double-gene deletion mutant of ORFV (rGS14ΔCBPΔGIF) and evaluated it as a vaccine candidate. Building on this previous work, the current study reports the construction of a new vaccine candidate, generated by deleting a third gene (gene 121) to generate ORFV rGS14ΔCBPΔGIFΔ121. The in vitro growth characteristics, as well as the in vivo safety, immunogenicity, and protective efficacy, were evaluated. RESULTS: There was a minor difference in viral replication and proliferation between ORFV rGS14ΔCBPΔGIFΔ121 and the other two strains. ORFV rGS14ΔCBPΔGIFΔ121 induced continuous differentiation of PBMC to CD4⁺T cells, CD8⁺T cells and CD80⁺CD86⁺ cells and caused mainly Th1-like cell-mediated immunity. By comparing the triple-gene deletion mutant with the parental strain and the double-gene deletion mutant, we found that the safety of both the triple-gene deletion mutant and the double-gene deletion mutant could reach 100% in goats, while the safety of parental virus was only 50% after continually observing immunized animals for 14 days. A virulent field strain of ORFV from an ORF scab was used in the challenge experiment by inoculating the virus to the hairless area of the inner thigh of immunized animals. The result showed that the immune protection rate of triple-gene deletion mutant, double-gene mutant, and the parental virus was 100%, 66.7%, and 28.6%, respectively. In conclusion, the safety, immunogenicity, and immune-protectivity of the triple-gene deletion mutant were greatly improved to 100%, making it an excellent vaccine candidate.

Human Orf with Immune-Mediated Reactions: A Systematic Review

Background: Orf is a highly contagious zoonosis caused by Orf virus (ORFV), which is endemic in sheep and goats worldwide. Human Orf is usually a self-limiting disease, but potential complications, including immune-mediated reactions, may occur. Methods: We included all articles regarding Orf-associated immunological complications published in peer-reviewed medical journals. We conducted a literature search of the United States National Library of Medicine, PubMed, MEDLINE, PubMed Central, PMC, and the Cochrane Controlled Trials. Results: A total of 16 articles and 44 patients were included, prevalently Caucasian (22, 95.7%) and female (22, 57.9%). The prevailing immunological reaction was erythema multiforme (26, 59.1%), followed by bullous pemphigoid (7, 15.9%). In most cases, the diagnosis was made on the basis of clinical and epidemiological history (29, 65.9%), while a biopsy of secondary lesions was performed in 15 patients (34.1%). A total of 12 (27.3%) patients received a local or systemic treatment for primary lesions. Surgical removal of primary lesion was described in two cases (4.5%). Orf-immune-mediated reactions were treated in 22 cases (50.0%), mostly with topical corticosteroids (12, 70.6%). Clinical improvement was reported for all cases. Conclusions: Orf-related immune reactions can have a varied clinical presentation, and it is important for clinicians to be aware of this in order to make a prompt diagnosis. The main highlight of our work is the presentation of complicated Orf from an infectious diseases specialist's point of view. A better understanding of the disease and its complications is essential to achieve the correct management of cases.

Next-generation sequencing approach to investigate genome variability of Parapoxvirus in Canadian muskoxen (Ovibos moschatus)

In 2016, the first orf virus, a double-stranded DNA (dsDNA) virus of the genus parapoxvirus, from a muskox was isolated on Victoria Island, Nunavut (NU), Canada. We used deep sequencing on DNA extracted from orf virus-positive tissues from wild muskoxen from locations on Victoria Island and the adjacent mainland. Orf virus sequence reads derived from four samples were nearly identical. The consensus sequences generated from pooled reads of MxOV comprises of a large contiguous sequence (contig) of 131,759 bp and a smaller right terminal contig of 3552 bp, containing all coding sequences identified as Parapoxvirus. Individual gene comparisons reveal that MxOV shares genetic characteristics with reference strains from both sheep and goat origin. Recombination analysis using Bootscan, MAXCHI, GENECONV, CHIMAERA, SISCAN, and RDP algorithms within the RDP4 software predicted recombination events in two virulence factors, and a large 3000 bp segment of the MxOV genome. Partial B2L nucleotide sequences from strains around the world and other North American isolates were compared to MxOV using MUSCLE alignments and RAxML phylogenetic trees. MxOV was identical to our previously characterized isolate, and shared similarity with orf virus isolated from sheep and goats. The phylogenetic grouping of partial B2L nucleotide sequences did not follow the sample geographic distribution. More full genomes of orf virus, or at least full B2L gene squences, in wildlife are needed especially in North America to better understand the epidemiology of the disease in muskoxen.

Orf virus induces complete autophagy to promote viral replication via inhibition of AKT/mTOR and activation of the ERK1/2/mTOR signalling pathway in OFTu cells

Orf virus (ORFV) is the causative agent of contagious ecthyma, which is an important zoonotic pathogen with a widespread distribution affecting sheep, goats and humans. Our previous research showed that autophagy can be induced in host cells by ORFV infection. However, the exact mechanism of ORFV-induced autophagy remains unknown. In this study, we investigated the underlying mechanisms of autophagy induced by ORFV in OFTu cells and the impact of autophagy on ORFV replication. By using specific autophagy inhibitors and activators, Western blotting, immunofluorescence and transmission electron microscopy imaging, we confirmed that ORFV infection triggered intracellular autophagosome accumulation and the activation of autophagic flux. Moreover, ORFV-induced autophagic activity was found to rely on an increase in the phosphorylation of tuberous sclerosis complex 2 (TSC2) and a decrease in the phosphorylation of mammalian target of rapamycin (mTOR), which is mediated by the suppression of the PI3K/AKT/mTOR signalling pathway and activation of the ERK1/2/mTOR signalling pathway. Furthermore, we investigated the role of mTOR-mediated autophagy during ORFV replication using pharmacological agents and demonstrated that ORFV-induced autophagy correlated positively with viral replication. Taken together, our data reveal the pathways of ORFV-induced autophagy and the impact of autophagy on ORFV replication, providing new insights into ORFV pathogenesis.

Recent advances in diagnostic approaches for orf virus

Orf virus (ORFV), the prototype species of the Parapoxvirus genus, is an important zoonotic virus, causing great economic losses in livestock production. At present, there are no effective drugs for orf treatment. Therefore, it is crucial to develop accurate and rapid diagnostic approaches for ORFV. Over decades, various diagnostic methods have been established, including conventional methods such as virus isolation and electron microscopy; serological methods such as virus neutralization test (VNT), immunohistochemistry (IHC) assay, immunofluorescence assay (IFA), and enzyme-linked immunosorbent assay (ELISA); and molecular methods such as polymerase chain reaction (PCR), real-time PCR, loop-mediated isothermal amplification (LAMP), recombinase polymerase amplification (RPA), and recombinase-aided amplification (RAA) assay. This review provides an overview of currently available diagnostic approaches for ORFV and discusses their advantages and limitations and future perspectives, which would be significantly helpful for ORFV early diagnosis and surveillance to prevent outbreak of orf. KEY POINTS: • Orf virus emerged and reemerged in past years • Rapid and efficient diagnostic approaches are needed and critical for ORFV detection • Novel and sensitive diagnostic methods are required for ORFV detection.

Rapid Onsite Visual Detection of Orf Virus Using a Recombinase-Aided Amplification Assay

Orf is an important zoonotic disease caused by the Orf virus (ORFV) which can cause contagious pustular dermatitis in goats and sheep. Orf is widespread in most sheep-raising countries in the world, causing huge economic losses. Although diagnostic methods for ORFV infection already exist, it is still necessary to develop a time-saving, labor-saving, specific, low-cost and visual diagnostic method for rapid detection of ORFV in the field and application in grassroots laboratories. This study establishes a DNA extraction-free, real-time, visual recombinase-aided amplification (RAA) method for the rapid detection of ORFV. This method is specific to ORFV and does not cross-react with other common DNA viruses. The detection limits of the real-time RAA and visual judgment of the RAA assay at 95% probability were 13 and 21 copies per reaction for ORFV, respectively. Compared with qPCR, the sensitivity and specificity of the real-time RAA assay were 100%, and those of the visual RAA assay were 92.31% and 100.0%, respectively. The DNA extraction-free visual detection method of RAA established in this study can meet the needs of rapid onsite detection and grassroots laboratories and has important reference value and significance for the early diagnosis of diseased animals.

ORFV can carry TRAP gene expression via intracellular CRISPR/Cas9 gene editing technology

Orf is an acute and highly contracted human and animal infection caused by orf virus (ORFV), which mainly affects sheep, goats, and other species. Clinically, opportunistic or conditional pathogens such as Staphylococcus aureus (S. aureus) are often detected in cases of orf, which greatly increases the risk of disease progression and clinical death. It has been reported that TRAP gene products of S. aureus can broadly influence bacterial life and pathogenicity in vivo, and introduction of exogenous TRAP genes may help to inhibit the proliferation of bacteria. In order to achieve the combined control of ORFV and S. aureus, a novel approach to design a S. aureus TRAP gene vaccine using a live attenuated ORFV vector is proposed. In this study, CRISPR/Cas9 gene editing technology was used to disable vascular endothelial growth factor E of ORFV (VEGF-v) and introduced TRAP gene into this position. TRAP gene expression was detected in keratinocytes infected with recombinant virus. The construction and experimental verification of recombinant ORFV (ORFV-v/TRAP) will provide a reference for in-depth studies on the prevention and control of mixed infectious disease.

Oncolytic Parapoxvirus induces Gasdermin E-mediated pyroptosis and activates antitumor immunity

The advantage of oncolytic viruses (OV) in cancer therapy is their dual effect of directly killing tumours while prompting anti-tumour immune response. Oncolytic parapoxvirus ovis (ORFV) and other OVs are thought to induce apoptosis, but apoptosis, being the immunogenically inert compared to other types of cell death, does not explain the highly inflamed microenvironment in OV-challenged tumors. Here we show that ORFV and its recombinant therapeutic derivatives are able to trigger tumor cell pyroptosis via Gasdermin E (GSDME). This effect is especially prominent in GSDME-low tumor cells, in which ORFV-challenge pre-stabilizes GSDME by decreasing its ubiquitination and subsequently initiates pyroptosis. Consistently, GSDME depletion reduces the proportion of intratumoral cytotoxic T lymphocytes, pyroptotic cell death and the success of tumor ORFV virotherapy. In vivo, the OV preferentially accumulates in the tumour upon systemic delivery and elicits pyroptotic tumor killing. Consequentially, ORFV sensitizes immunologically 'cold' tumors to checkpoint blockade. This study thus highlights the critical role of GSDME-mediated pyroptosis in oncolytic ORFV-based antitumor immunity and identifies combinatorial cancer therapy strategies.

Deletion of gene OV132 attenuates Orf virus more effectively than gene OV112

Orf virus (ORFV), a Parapoxvirus in Poxviridae, infects sheep and goats resulting in contagious pustular dermatitis. ORFV is regarded as a promising viral vector candidate for vaccine development and oncolytic virotherapy. Owing to their potential clinical application, safety concerns have become increasingly important. Deletion of either the OV132 (encoding vascular endothelial growth factor, VEGF) or OV112 (encoding the chemokine binding protein, CBP) genes reduced ORFV infectivity, which has been independently demonstrated in the NZ2 and NZ7 strains, respectively. This study revealed that the VEGF and CBP gene sequences of the local strain (TW/Hoping) shared a similarity of 47.01% with NZ2 and 90.56% with NZ7. Due to the high sequence divergence of these two immunoregulatory genes among orf viral strains, their contribution to the pathogenicity of Taiwanese ORFV isolates was comparatively characterized. Initially, two ORFV recombinants were generated, in which either the VEGF or CBP gene was deleted and replaced with the reporter gene EGFP. In vitro assays indicated that both the VEGF-deletion mutant ORFV-VEGFΔ-EGFP and the CBP deletion mutant ORFV-CBPΔ-EGFP were attenuated in cells. In particular, ORFV-VEGFΔ-EGFP significantly reduced plaque size and virus yield compared to ORFV-CBPΔ-EGFP and the wild-type control. Similarly, in vivo analysis revealed no virus yield in the goat skin biopsy infected by ORFV-VEGFΔ-EGFP, and significantly reduced the virus yield of ORFV-CBPΔ-EGFP relative to the wild-type control. These results confirmed the loss of virulence of both deletion mutants in the Hoping strain, whereas the VEGF-deletion mutant was more attenuated than the CBP deletion strain in both cell and goat models. KEY POINTS: • VEGF and CBP genes are crucial in ORFV pathogenesis in the TW/Hoping strain • The VEGF-deletion mutant virus was severely attenuated in both cell culture and animal models • Deletion mutant viruses are advantageous vectors for the development of vaccines and therapeutic regimens.

Orf virus DNA prime-protein boost strategy is superior to adenovirus-based vaccination in mice and sheep

Contagious ecthyma (Orf), an acute and highly contagious zoonosis, is prevalent worldwide. Orf is caused by Orf virus (ORFV), which mainly infects sheep/goats and humans. Therefore, effective and safe vaccination strategies for Orf prevention are needed. Although immunization with single-type Orf vaccines has been tested, heterologous prime-boost strategies still need to be studied. In the present study, ORFV B2L and F1L were selected as immunogens, based on which DNA, subunit and adenovirus vaccine candidates were generated. Of note, heterologous immunization strategies using DNA prime-protein boost and DNA prime-adenovirus boost in mice were performed, with single-type vaccines as controls. We have found that the DNA prime-protein boost strategy induces stronger humoral and cellular immune responses than DNA prime-adenovirus boost strategy in mice, which was confirmed by the changes in specific antibodies, lymphocyte proliferation and cytokine expression. Importantly, this observation was also confirmed when these heterologous immunization strategies were performed in sheep. In summary, by comparing the two immune strategies, we found that DNA prime-protein boost strategy can induce a better immune response, which provides a new attempt for exploring Orf immunization strategy.

Evaluation of the Immune Response Afforded by Combined Immunization with Orf Virus DNA and Subunit Vaccine in Mice

Contagious ecthyma (Orf) is a highly contagious disease caused by Orf virus (ORFV) infection. Orf is prevalent all over the world and, not only affects the healthy development of sheep husbandry, but also threatens human health. However, there are no safe and effective vaccines or drugs for the prevention and treatment of Orf at present. In this study, we constructed a DNA plasmid expressing ORFV B2L and F1L genes as a DNA vaccine candidate, with purified B2L full-length protein and F1L truncated protein as subunit vaccine candidates. BALB/c mice were immunized with the DNA vaccine, subunit vaccine, as well as DNA prime-protein boost strategies. The results showed that compared with the DNA vaccine and subunit vaccine alone, the DNA prime-protein boost immunization group had a higher level of specific antibodies, stronger lymphocyte proliferation, and higher expression of cytokines such as IL-2, IL-4, IL-6, IFN-γ, and TNF-α, which are considered to cause a Th1/Th2 mixed cytokine response. Our results demonstrated that the DNA prime-protein boost immunization strategy induced stronger humoral and cellular immune responses, which have potential advantages in preventing ORFV infection.

ORFV infection enhances CXCL16 secretion and causes oncolysis of lung cancer cells through immunogenic apoptosis

Oncolytic viruses have been emerging as a promising therapeutic option for cancer patients, including lung cancer. Orf virus (ORFV), a DNA parapoxvirus, can infect its natural ungulate hosts and transmit into humans. Moreover, the ORFV has advantages of low toxicity, high targeted, self-amplification and can induce potent Th1-like immunity. This study explored the therapeutic potential of ORFV infection for human lung cancer therapy and investigated the molecular mechanisms. We used a previously described ORFV NA1/11 strain and tested the oncolysis of ORFV NA1/11 in two lines of lung cancer cells in vitro and in vivo. Treatment of both cell lines with ORFV NA1/11 resulted in a decrease in cell viability by inducing cell cycle arrest in G2/M phase, suppressing cyclin B1 expression and increasing their apoptosis in a caspase-dependent manner. The ORFV NA1/11-infected lung cancer cells were highly immunogenic. Evidently, ORFV NA1/11 infection of lung cancer cells induced oncolysis of tumor cells to release danger-associated molecular patterns, and promoted dendritic cell maturation, and CD8 T cell infiltration in the tumors by enhancing CXCL16 secretion. These findings may help to understand the molecular mechanisms of ORFV oncolysis and aid in the development of novel therapies for lung cancer.

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

Orf virus (ORFV) is distributed worldwide and is the causative agent of contagious ecthyma that mainly occurs in sheep and goats. This disease was reported for the first time at the end of 18th century in Europe but very little is currently known about the temporal and geographic origins of this virus. In the present study, the use of new Italian whole genomes allowed for better inference on the evolutionary history of ORFV. In accordance with previous studies, two genome types (S and G) were described for infection of sheep and goats, respectively. These two well-differentiated groups of genomes originated for evolutive convergence in the late 1800s in two different areas of the world (Europe for S type and Asia for G type), but it was only in the early 1900s that the effective size of ORFV increased among hosts and the virus spread across the whole European continent. The Italian strains which were sequenced in the present study were isolated on the Mediterranean island of Sardinian and showed to be exclusive to this geographic area. One of them is likely representative of the early European forms of ORFV which infected sheep and became extinct about one century ago. Such an ancient Sardinian strain may have reached the island simple by chance, where it quickly adapted to the new habitat.

Preclinical efficacy and involvement of mTOR signaling in the mechanism of Orf virus against nasopharyngeal carcinoma cells

AIMS

Orf virus (ORFV) is a parapoxvirus causing contagious ecthyma in sheep and goats. With inhibitory role of ORFV reported by previous studies, ORFV can be a candidate of oncolytic virus. However, few studies reported the application and mechanism of ORFV in nasopharyngeal carcinoma (NPC). We aimed to elucidate the anti-tumor mechanism of ORFV against NPC cells.

MATERIALS AND METHODS

The anti-tumor effect of ORFV in NPC cells was confirmed by cell counting kit 8 (CCK-8) assay, flow cytometry and Western blot. In vitro and in vivo experiments were adopted to evaluate the inhibitory effect of ORFV in NPC cells. Western blot was used to determine the down-regulation of rapamycin (mTOR) signaling and autophagy enhancement induced by ORFV. To explore the mechanism of ORFV on NPC cells, mTOR signaling agonist and autophagy inhibitors were used to rescue the effects of ORFV.

KEY FINDINGS

The results indicated that ORFV replicates in NPC cells, thus induces the apoptosis of NPC cells. Moreover, ORFV can effectively inhibit NPC cell growth in vivo. ORFV infection in NPC cells leads to the mTOR signaling inhibition and up-regulated autophagy, which might be the specific mechanism of ORFV in killing tumor cells. As to safety confirmation, normal nasopharyngeal epithelial cells NP69 are insensitive to ORFV. More importantly, ORFV would not cause organ damage in vivo.

SIGNIFICANCES

Our data clarified that ORFV induces autophagy of NPC cells via inhibiting mTOR signaling, thus further inducing apoptosis. The anti-tumor role of ORFV might provide a preclinical strategy for NPC treatment.

Orf virus infection of the hand in a Scottish sheep farmer. A case report to increase awareness to avoid misdiagnosis

Awareness of infections which are transmitted between animals and humans have been given prominence following the (COVID-19) pandemic. The Orf infection in humans is rare. Recognition of Orf lesions avoids misdiagnosing and incorrect treatment. We present a case of a Scottish-farmer with pain and discomfort from a lesion on her finger.

Immunomodulatory Strategies for Parapoxvirus: Current Status and Future Approaches for the Development of Vaccines against Orf Virus Infection

Orf virus (ORFV), the prototype species of the parapoxvirus genus, is the causative agent of contagious ecthyma, an extremely devastating skin disease of sheep, goats, and humans that causes enormous economic losses in livestock production. ORFV is known for its ability to repeatedly infect both previously infected and vaccinated sheep due to several immunomodulatory genes encoded by the virus that temporarily suppress host immunity. Therefore, the development of novel, safe and effective vaccines against ORFV infection is an important priority. Although, the commercially licensed live-attenuated vaccines have provided partial protection against ORFV infections, the attenuated viruses have been associated with major safety concerns. In addition to safety issues, the persistent reinfection of vaccinated animals warrants the need to investigate several factors that may affect vaccine efficacy. Perhaps, the reason for the failure of the vaccine is due to the long-term adaptation of the virus in tissue culture. In recent years, the development of vaccines against ORFV infection has achieved great success due to technological advances in recombinant DNA technologies, which have opened a pathway for the development of vaccine candidates that elicit robust immunity. In this review, we present current knowledge on immune responses elicited by ORFV, with particular attention to the effects of the viral immunomodulators on the host immune system. We also discuss the implications of strain variation for the development of rational vaccines. Finally, the review will also aim to demonstrate future strategies for the development of safe and efficient vaccines against ORFV infections.

Acral manifestations associated with infection

Acral lesions are well-known physical findings in various infectious disorders. Although they are often overlooked, they can be the key to the diagnosis of the underlying disease. Considering this, we present an overview of various infectious causes of acral lesions in childhood. In addition, we discuss their characteristic presentation, evolution, and appropriate treatment. To our knowledge, this is the first review covering viral, bacterial and mycotic causes.

Study on the Role of the Common House Fly, Musca domestica, in the Spread of ORF Virus (Poxviridae) DNA under Laboratory Conditions

ORF virus (Poxviridae) is the causative agent of contagious ecthyma (soremouth), a disease primarily affecting sheep and goats worldwide, but also humans exposed to disease-ridden animals. Pathogens are shed with scabs, and infection mainly occurs by direct contact. Although the disease is relatively benign and self-limiting, the morbidity rate is high in livestock with subsequent significant financial and economic impact. The aim of the study was to experimentally investigate the potential for the housefly, Musca domestica, to act as a mechanical vector of the virus. Homogenate of crusted scabs from ORFV-positive sheep (Italy, Apulia) were used to infect laboratory-reared flies. Flies walking on viral mixture and flies inoculated on their wings were individually placed in Falcon tubes and the ORFV DNA was searched by PCR on tube walls; flies were fed on the same homogenized crusts and their crop and spots (vomit and feces) molecularly examined for ORF DNA at 2, 4, and 6 h. All of the flies (100%) used in the experiments were able to pick up and transmit the viral genome to contact surfaces; 60% were found ORF virus (DNA)-positive in both spots and crop. These results suggest that M. domestica could play a role as potential mechanical vector and/or reservoir in the epidemiology of the ORF virus infection. Thus, house fly management should be considered in the measures to control the disease in ovine-caprine farms.

Orf virus ORF120 protein positively regulates the NF-κB pathway by interacting with G3BP1

Orf virus (ORFV) is a highly epitheliotropic parapoxvirus with zoonotic significance that induces proliferative lesions in the skin of sheep, goats, and humans. Several viral proteins carried by ORFV, including nuclear factor-κB (NF-κB) inhibitors, play important roles in hijacking host-associated proteins for viral evasion of the host innate immune response. However, the roles of proteins with unknown functions in viral replication and latent infection remain to be explored. Here, we present data demonstrating that the ORF120, an early-late ORFV-encoded protein, activates the NF-κB pathway in the early phase of infection, which implies that ORFV may regulate NF-κB through a biphasic mechanism. A DUAL membrane yeast two-hybrid system and coimmunoprecipitation experiments revealed that the ORF120 protein interacts with Ras-GTPase-activating protein (SH3 domain) binding protein 1 (G3BP1). The overexpression of the ORF120 protein can efficiently increase the expression of G3BP1 and nuclear translocation of NF-κB-p65 in primary ovine fetal turbinate (OFTu) and HeLa cells. The knockdown of G3BP1 significantly decreased ORF120-induced NF-κB activation, indicating that G3BP1 is involved in ORF120-induced NF-κB pathway activation. A dual-luciferase reporter assay revealed that ORF120 could positively regulate the NF-κB pathway through the full-length G3BP1 or the domain of G3BP1^RRM+RGG. In conclusion, we demonstrate, for the first time, that the ORF120 protein is capable of positively regulating NF-κB signaling by interacting with G3BP1, providing new insights into ORFV pathogenesis and a theoretical basis for antiviral drug design.

IMPORTANCE As part of the host innate response, the nuclear factor-κB (NF-κB) pathway plays a partial antiviral role in nature by regulating the innate immune response. Thus, the NF-κB pathway is probably the most frequently targeted intracellular pathway for subversion by anti-immune modulators that are carried by a wide range of pathogens. Various viruses, including poxviruses, carry several proteins that prepare the host cell for viral replication by inhibiting cytoplasmic events, leading to the initiation of NF-κB transcriptional activity. However, NF-κB activity is hypothesized to facilitate viral replication to a great extent. The significance of our research is in the exploration of the activation mechanism of NF-κB induced by the Orf virus (ORFV) ORF120 protein interacting with G3BP1, which helps not only to explain the ability of ORFV to modulate the immune response through the positive regulation of NF-κB but also to show the mechanism by which the virus evades the host innate immune response.

A Review on Human Orf: A Neglected Viral Zoonosis

Orf virus (ORFV) is the etiologic agent of Orf or ecthyma contagiosum in humans but primarily affects different domestic and wild animals. The disease mostly affects sheep, goats and other small wild ruminants and spreads to humans through direct contact with infected animals or by way of contaminated fomites worldwide. ORFV is taxonomically classified as a member of the genus Parapoxvirus. It is known to have tolerance to inactivation in a drier environment, and it has been recovered from crusts after several months to years. Among immunocompetent people, the lesions usually resolve by its natural course within a maximum of 8 weeks. In immunosuppressed patients, however, it needs the use of various approaches including antiviral, immune modifier or minor surgical excisions. The virus through its association with divergent host ranges helps to develop a mechanism to evade the immune system. The relative emergence of Orf, diagnosed on clinical ground among human cases, in unusual frequencies in southwest Ethiopia between October 2019 and May 2020, was the driver to write this review. The objective was to increase health care providers' diagnostic curiosity and to bring the attentiveness of public health advisors for prevention, control and the development of schemes for surveillance of Orf zoonosis in a similar setting like Ethiopia.

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

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.

Molecular characterization and phylogenetic analysis of orf virus isolated from goats in Sokoto metropolis, Nigeria

Aim:

The aim of this study was to molecularly characterize orf virus isolated from clinical infections in goats in Sokoto metropolis.

Materials & methods:

Embryonated chicken eggs were used to isolate orf virus according to the established protocol. Viral DNA was extracted and full coding region of B2L gene was amplified by polymerase chain reaction, sequenced and blasted for identification and phylogenetically analyzed.

Results and discussion:

The B2L gene sequences of the isolate showed slight variability (96–98.7%) with the reference sequences as it clustered within the same clade with Korean, Zambian and Ethiopian strains, signifying a close genetic relationship. Unique amino acid substitutions were noted. This is the first genetic characterization of B2L gene of orf virus circulating in Nigeria.

Conclusion:

This study has provided in sight into the genetic diversity of orf virus in the study area.

Contagious ecthyma has for long been affecting the goat and sheep population in Nigeria leading to huge economic losses to livestock farmers through death and poor market value of the affected animals. Recently, increased death due to this disease has been reported in north-central Nigeria, but the nature of the disease-causing agent has not been reported yet. It is the aim of this study to understand the nature of the virus causing the disease in goats in Sokoto using molecular biology techniques so as to facilitate better vaccine design for the effective control of the disease in Nigeria.

Viral Infections in Burn Patients: A State-Of-The-Art Review

Infections that are triggered by the accompanying immunosuppression in patients with burn wounds are very common regardless of age. Among burn patients, the most frequently diagnosed infections include the bacterial ones primarily caused by Pseudomonas aeruginosa or Klebsiella pneumonia, as well as fungal infections with the etiology of Candida spp. or Aspergillus spp. Besides, burn wounds are highly susceptible to viral infections mainly due to the impaired immune responses and defective functions of the immune cells within the wound microenvironment. The most prevalent viruses that invade burn wounds include herpes simplex virus (HSV), cytomegalovirus (CMV), human papilloma virus (HPV), and varicella zoster virus (VZV). Likewise, less prevalent infections such as those caused by the orf virus or Epstein-Barr Virus (EBV) might also occur in immunosuppressed burn patients. Viral infections result in increased morbidity and mortality rates in severely burned patients. Additionally, a positive correlation between the hospitalization duration and the severity of the viral infection has been demonstrated. Viral infections trigger the occurrence of various complications, ranging from mild symptoms to even fatal incidents. Accurate detection of viral infection is of great clinical importance because of the possibility for a quicker introduction of proper treatment therapy and shortening of hospitalization time. The aim of this paper is to provide a comprehensive review of the literature and summarize the findings regarding the most common viral infections in immunosuppressed burn patients.

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.

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.

Rescue of a Vaccinia Virus Mutant Lacking IFN Resistance Genes K1L and C7L by the Parapoxvirus Orf Virus

Type 1 interferons induce the upregulation of hundreds of interferon-stimulated genes (ISGs) that combat viral replication. The parapoxvirus orf virus (ORFV) induces acute pustular skin lesions in sheep and goats and can reinfect its host, however, little is known of its ability to resist IFN. Vaccinia virus (VACV) encodes a number of factors that modulate the IFN response including the host-range genes C7L and K1L. A recombinant VACV-Western Reserve (WR) strain in which the K1L and C7L genes have been deleted does not replicate in cells treated with IFN-β nor in HeLa cells in which the IFN response is constitutive and is inhibited at the level of intermediate gene expression. Furthermore C7L is conserved in almost all poxviruses. We provide evidence that shows that although ORFV is more sensitive to IFN-β compared with VACV, and lacks homologues of KIL and C7L, it nevertheless has the ability to rescue a VACV KIL- C7L- gfp+ mutant in which gfp is expressed from a late promoter. Co-infection of HeLa cells with the mutant and ORFV demonstrated that ORFV was able to overcome the block in translation of intermediate transcripts in the mutant virus, allowing it to progress to late gene expression and new viral particles. Our findings strongly suggest that ORFV encodes a factor(s) that, although different in structure to C7L or KIL, targets an anti-viral cellular mechanism that is a highly potent at killing poxviruses.

Inhibition of orf virus replication in goat skin fibroblast cells by the HSPA1B protein, as demonstrated by iTRAQ-based quantitative proteome analysis

Orf virus (ORFV) infects sheep and goat tissues, resulting in severe proliferative lesions. To analyze cellular protein expression in ORFV-infected goat skin fibroblast (GSF) cells, we used two-dimensional liquid chromatography-tandem mass spectrometry coupled with isobaric tags for relative and absolute quantification (iTRAQ). The proteomics approach was used along with quantitative reverse transcription polymerase chain reaction (RT-qPCR) to detect differentially expressed proteins in ORFV-infected GSF cells and mock-infected GSF cells. A total of 282 differentially expressed proteins were identified. It was found that 222 host proteins were upregulated and 60 were downregulated following viral infection. We confirmed that these proteins were differentially expressed and found that heat shock 70-kDa protein 1B (HSPA1B) was differentially expressed and localized in the cytoplasm. It was also noted that HSPA1B caused inhibition of viral proliferation, in the middle and late stages of viral infection. The differentially expressed proteins were associated with the biological processes of viral binding, cell structure, signal transduction, cell adhesion, and cell proliferation.

Comparative analysis, distribution, and characterization of microsatellites in Orf virus genome

Genome-wide in-silico identification of microsatellites or simple sequence repeats (SSRs) in the Orf virus (ORFV), the causative agent of contagious ecthyma has been carried out to investigate the type, distribution and its potential role in the genome evolution. We have investigated eleven ORFV strains, which resulted in the presence of 1,036-1,181 microsatellites per strain. The further screening revealed the presence of 83-107 compound SSRs (cSSRs) per genome. Our analysis indicates the dinucleotide (76.9%) repeats to be the most abundant, followed by trinucleotide (17.7%), mononucleotide (4.9%), tetranucleotide (0.4%) and hexanucleotide (0.2%) repeats. The Relative Abundance (RA) and Relative Density (RD) of these SSRs varied between 7.6-8.4 and 53.0-59.5 bp/kb, respectively. While in the case of cSSRs, the RA and RD ranged from 0.6-0.8 and 12.1-17.0 bp/kb, respectively. Regression analysis of all parameters like the incident of SSRs, RA, and RD significantly correlated with the GC content. But in a case of genome size, except incident SSRs, all other parameters were non-significantly correlated. Nearly all cSSRs were composed of two microsatellites, which showed no biasedness to a particular motif. Motif duplication pattern, such as, (C)-x-(C), (TG)-x-(TG), (AT)-x-(AT), (TC)- x-(TC) and self-complementary motifs, such as (GC)-x-(CG), (TC)-x-(AG), (GT)-x-(CA) and (TC)-x-(AG) were observed in the cSSRs. Finally, in-silico polymorphism was assessed, followed by in-vitro validation using PCR analysis and sequencing. The thirteen polymorphic SSR markers developed in this study were further characterized by mapping with the sequence present in the database. The results of the present study indicate that these SSRs could be a useful tool for identification, analysis of genetic diversity, and understanding the evolutionary status of the virus.

Orf virus infection after Eid al-Adha

Human orf, also called ecthyma contagiosum, is a zoonotic infection that causes self-resolving skin lesions after contact with infected livestock. We present the case of a 45-year-old Moroccan-born man who developed multiple painful erythematous, violaceous plaques on his hands after butchering a sheep to celebrate the Muslim holiday Eid al-Adha. The diagnosis of orf virus infection was established based on exposure history, histopathology, and classic skin lesions. Although orf virus infection is traditionally seen in individuals with frequent animal contact such as farmers and veterinarians, clinicians evaluating suspicious lesions in patients without occupational risk factors should consider additional cultural practices that may expose the patient to orf virus.

Orf Virus VIR Antagonizes p53-Mediated Antiviral Effects to Facilitate Viral Replication

As a zoonotic disease, ovine contagious pustular dermatitis (Orf) is a serious threat to sheep as well as humans. Orf virus (ORFV) interferon resistance protein (VIR) is the principal virulence protein that encodes a dsRNA-binding protein to inhibit host antiviral response. p53 is one of the key proteins of the host antiviral innate immunity. It not only enhances type I interferon secretion but also induces apoptosis in infected cells, and plays a crucial role in the immune response against various viral infections. However, it remains to be elucidated what role p53 plays in ORFV replication and whether ORFV's own protein VIR regulates p53 expression to promote self-replication. In this study, we showed that p53 has an antiviral effect on ORFV and can inhibit ORFV replication. In addition, ORFV nonstructural protein VIR interacts with p53 and degrades p53, which inhibits p53-mediated positive regulation of downstream antiviral genes. This study provides new insight into the immune evasion mediated by ORFV and identifies VIR as an antagonistic factor for ORFV to evade the antiviral response.

Field investigation and phylogenetic characterization of orf virus (ORFV) circulating in small ruminants and Pseudocowpoxvirus (PCPV) in dromedary camels of eastern Sudan

In this study, livestock herders in eastern Sudan were interviewed through structured questionnaire involved 14046 animals in 151 herds (87 camel herds, 51 sheep and 13 goats) from June to September of 2016 in Showak area of Gadarif State to get some epidemiological information on contagious ecthyma (CE) infection. 102 suspected cases of CE were investigated (38 sheep, 22 goats and 42 camels) by a second questionnaire focusing on age and sex of affected animals beside number and localization of the lesions. Representative tissue samples of scab lesion scrapings were collected from a total of 36 suspected sheep, goats and camels for DNA extraction to identify PPV by quantitative real-time PCR and gel-based PCR, then a PCR protocol was used to obtain DNA fragment of B2L gene from six DNAs (2 from each animal species) for sequencing. Phylogenetic tree based on nucleotide sequences was constructed and all data were analyzed statistically. Obtained result has shown morbidity rate of 23.8% and a case fatality rate of 4.7 % in overall investigated animals resulting in a significant economic loss. Within individual herd, the morbidity rate varied from 5.6 to 42.8%, while the case fatality rate ranged between 0 and 33.3%. Camels accounted for the highest case fatality rate with 6.5% compared to sheep and goats which their rates were 2.8% and 1.3%, respectively. 93% of the affected animals were young less than one-year-old. The prevalence of CE was high in the rainy season compared to winter and summer. Out of 36 scab materials collected from sheep, goats, and camels, 24 gave positive specific amplification in real-time PCR and 21 in the gel-based PCR. DNA sequencing confirmed the PCR results. All sequences had a high G + C content of 62.6-63.9%. A BLAST search also revealed that the studied sheep PPV (SPPV) isolates shared 99.08% nucleotide sequence intragroup identity, 96.88-97.27% identity with the goat PPV (GPPV) isolates and together they belong to the Orf virus (ORFV) species, while the camel PPV (CPPV) isolates are close to the Pseudocowpoxvirus (PCPV) species of the PPV genus and share 92.51-93.62 % identity with the GPPV isolates. In conclusion the present study demonstrated that the gross lesion produced by PPV in sheep, goats and camels is generally similar, yet the PPVs circulating in eastern Sudan in camels (PCPV) are genetically distinct from those affecting sheep and goats (ORFV). Contagious ecthyma in eastern Sudan causes significant morbidities and mortalities and control measures, guided by the results of this investigation ought to be implemented.

Integrated Analysis of Differentially Expressed miRNAs and mRNAs in Goat Skin Fibroblast Cells in Response to Orf Virus Infection Reveals That cfa-let-7a Regulates Thrombospondin 1 Expression

Orf is a zoonotic disease that has caused huge economic losses globally. Systematical analysis of dysregulated cellular micro RNAs (miRNAs) in response to Orf virus (ORFV) infection has not been reported. In the current study, miRNA sequencing and RNA sequencing (RNA-seq) were performed in goat skin fibroblast (GSF) cells at 0, 18, and 30 h post infection (h.p.i). We identified 140 and 221 differentially expressed (DE) miRNAs at 18 and 30 h.p.i, respectively. We also identified 729 and 3961 DE genes (DEGs) at 18 and 30 h.p.i, respectively. GO enrichment analysis indicates enrichment of apoptotic regulation, defense response to virus, immune response, and inflammatory response at both time points. DE miRNAs and DEGs with reverse expression were used to construct miRNA-gene networks. Seven DE miRNAs and seven DEGs related to "negative regulation of viral genome replication" were identified. These were validated by RT-qPCR. Cfa-let-7a, a significantly upregulated miRNA, was found to repress Thrombospondin 1 (THBS1) mRNA and protein expression by directly targeting the THBS1 3' untranslated region. THBS1 has been reported to induce apoptosis; therefore, the cfa-let-7a-THBS1 axis may play an important role in cellular apoptosis during ORFV infection. This study provides new insights into ORFV and host cell interaction mechanisms.

Establishment and characterization of transformed goat primary cells by expression of simian virus 40 large T antigen for orf virus propagations

Due to the limited host range of orf virus (ORFV), primary cells derived from its natural hosts, such as goats and sheep, are recommended for isolation and propagation of wild type ORFV. This situation limits the option for the study of virus-host interaction during ORFV infection since primary cells only support a few numbers of passages. SV40 T antigen is a viral oncoprotein that can abrogate replicative senescence, leading to an extended life span of cells. In this study, the transformation of two goat primary cells, fibroblast (FB) and testis (GT) cells, were achieved by stably expressing SV40 T antigen using the lentiviral technique. The presence of the gene encoding SV40 T antigen was validated by polymerase chain reaction (PCR) and western blot analyses. As evidenced by immunofluorescent microscopy, the two types of cells expressing SV40 T antigen (namely, FBT and GTT) were purified to homogeneity. Moreover, faster growth kinetics and a lower serum dependency were noticed in FBT and GTT, as compared with their counterpart parental cells. FBT and GTT remain permissive and can form plaque of ORFV, despite with different profiles; generally speaking, with SV40 T expression, ORFV forms plaques with smaller size and distinct margin. Most importantly, the prolonged life span of goat FBT and GTT serves as an ideal cell culture resource for ORFV isolation from the field, studies of ORFV pathogenesis and efficient vaccine development.

An association of Orf virus infection among sheep and goats with herd health programme in Terengganu state, eastern region of the peninsular Malaysia

BACKGROUND

Orf virus causes a scabby skin lesions which decreases productivity in small ruminants. The unknown status of this disease in the eastern region of Peninsular Malaysia warrants a study to determine sero-prevalence of orf with regards to farmers' compliance level towards the Herd Health Program (HHP) programme.

RESULTS

Out of 504 animals, 115 were positive for Orf-virus antibodies. An overall prevalence rate of 22.8% indicated a high prevalence of orf disease in this region. It was observed that 25.1% (92/367) of goats were positive and 16.8% (23/137) of sheep sero-converted for Orf virus antibody. Several factors were measured for their possible association with prevalence of Orf virus infection. The prevalence was higher in LY farm, JC breed, kid and female animals, and in the presence of disease lesion. Chi-square analysis showed a significant association of three risk factors which are species, age and sex of the animals (P < 0.05). Notwithstanding, all other variables showed no significant difference (P > 0.05). Farms surveyed usually practised intensive management system, keeping animals in the shade at all time, due to limited availability of suitable land as a free-range grazing area. An interview with small holder farmers revealed a lack of awareness of the main goals of herd health programme. An overall compliance level of 42.7% was observed for all HHP parameters. Among the 14 main components of HHP modules, animal identification had recorded highest compliance level (84.62%) while milking management recorded the least compliance (- 82.69%). That explained why there was a high sporadic prevalence of Orf infection in this region.

CONCLUSION

Good herd health supervision is a rehearsal target to prevent an outbreak and the spread of diseases thus reduces economic losses among farmers. Therefore, a good herd health programme should be in place, in order to prevent and control disease transmission as well as to improve herd immunity.

Genomic characterization of two Orf virus isolates from Jilin province in China

Orf virus (ORFV), a typical member of the Parapoxvirus genus within the family Poxviridae, which is the causative agent of Orf, a common epitheliotropic viral disease of sheep, goats, wild ruminants, and humans. In the present study, we sequenced the complete genomic sequences of two ORFV strains (ORFV-SY17, isolated from sheep, and ORFV-NA17, isolated from goat) and conducted the comparative analysis of multiple ORFVs. The complete genomic sequence of ORFV-SY17 was at length of 140,413 bp, including 131 potential open reading frames (ORFs) flanked by inverted terminal repeats (ITRs) of 4267 bp at both ends. The ORFV-NA17 strain displayed the similar genome structure with ORFV-SY17. The whole genomic sequence of ORFV-NA17 strain was 139,287 bp in length and contained 132 ORFs flanked by ITRs of 3974 bp. The overall G+C contents of ORFV-SY17 and ORFV-NA17 genome sequences were about 63.8% and 63.7%, respectively. The ITR sequences analysis showed that ORFV-SY17 and ORFV-NA17 contained the terminal BamHI sites and conserved telomere resolution sequences at both ends of their genome. In addition, comparative analysis of ORFs among ORFV-SY17, ORFV-NA17, and other ORFV strains revealed several sequence variations caused by insertions or deletions, especially in ORFs 005 and 116, which were very likely associated with host species. Phylogenetic analysis based on the complete genome sequences revealed that ORFV-SY17 was genetically closely related to NA1/11 and HN3/12 strains derived from sheep, while ORFV-NA17 was closely related to YX strain derived from goat. The multiple alignment of deduced amino acid sequences further revealed the genetic relationship between host species and genetic variations of ORFV strains. Taken together, the availability of genomic sequences of ORFV-SY17 and ORFV-NA17 strains from Jilin Province will aid in our understanding of the genetic diversity and evolution of ORFV strains in this region and can assist in distinguishing between ORFV strains that originate in sheep and goats.

Orf virus circulation in cattle in Turkey

Orf virus (ORFV) causes contagious skin disease that mainly affects sheep and goats with zoonotic potential. However, there is not enough information about the association between ORFV and occurrence of skin disease in cattle. The present study describes outbreaks of ORFV infection in cattle in different provinces that are located in the Aegean, Central Anatolian and Mediterranean regions of Turkey. During the months of June and August 2017, vesicular fluid and scab samples were collected from cattle which had proliferative skin lesions. First, presence of lumpy skin disease virus (LSDV) and bovine herpesvirus 2 (BoHV-2, known as the causative agent of pseudo-lumpy skin disease) were investigated by real time PCR and PCR, respectively. Then, samples tested for the presence of parapoxviruses by PCR using primers specific to major envelope protein gene (B2L). Parapoxvirus DNA was detected in investigated samples whereas LSDV and BoHV-2 DNA were not detected. The analysis of the B2L gene sequences revealed that cattle were infected with ORFV. The isolates in the present study shared 100% sequence identity at the nucleotide and amino acid level when compared with previously characterised Turkish field ORFV isolates from goats in 2016. Results of the study show unusual infection of cattle with ORFV, and suggest that ORFV jumps the host species barrier from goats to cattle.

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.

Detection and phylogenetic analysis of Orf virus in Kashmir Himalayas

Orf virus (ORFV) is a zoonotic pathogen that primarily infects sheep and goats, and is responsible for significant economic losses. ORFV is endemic in all the major sheep and goat rearing areas of the world including Indian subcontinent. However, the nature of ORFV circulating among sheep and goat in Kashmir Himalayas has not yet been characterized. In the present study, we describe natural outbreaks of ORFV in sheep and goats of Kashmir Himalayas. We detected the presence of ORFV in the scab lesion by PCR amplification of the major envelope protein (B2L) gene. We sequenced the virus interferon resistance (VIR) gene and determined their phylogenetic relationship with that of the published reference sequences. Phylogenetic analysis based on VIR gene revealed that the ORFV isolates from Kashmir Himalayas separated into main two clusters. The sheep isolates showed genetic homology with the sheep strains reported from Greece and Italy, whereas the goat-specific strain show homology with the goat strains reported from China. This study demonstrates the presence of ORFV infection in sheep and goats, and report first phylogenetic analysis of the ORFV strains prevalent in the Kashmir Himalayas.

Orf Virus Encoded Protein ORFV119 Induces Cell Apoptosis Through the Extrinsic and Intrinsic Pathways

Apoptosis, a significant form of cell death, has a leading role in the host cell defense against virus infection. Viruses have evolved a series of strategies that block apoptosis during the early stage of viral infection to enhance viral replication, and induce apoptosis in the late stages to facilitate viral particle release from the cells. Here we show that orf virus (ORFV), the causative agent of orf, encodes an apoptosis-inducing protein ORFV119. ORFV119 targets the mitochondria in host cells, inhibits cell proliferation, and induces cell apoptosis. Protein array data indicated that ORFV119 could induce apoptosis via up-regulation of Smac, Bak, and Bax and down-regulation of anti-apoptotic proteins Bcl-2 and cIAP-2. Activation of caspase-9 and caspase-3, and consequent PARP cleavage, ultimately lead to apoptosis. ORFV119 could also directly activate caspase-8 and induce Bid, involved in the extrinsic pathway, to achieve cell death. Furthermore, sequence analysis and experiments with mutants of ORFV119 introduced revealed that ORFV119 contains a key N-terminal domain that is necessary and sufficient to direct the protein to the mitochondria. Together, we report, for the first time, the identification of the novel apoptosis-inducing protein ORFV119 encoded by a parapoxvirus. This provides an important reference for the study of pathogenesis, identification of immunomodulation mechanisms of ORFV, and may lead to new strategies for orf disease control.