Identification and molecular characterization of Orf virus in Argentina

Contagious ecthyma in small ruminants: from etiology to vaccine challenges - a review

Orf virus (ORFV) is an epitheliotropic, double-stranded DNA pathogen belonging to the genus Parapoxvirus, and it is the causative agent of contagious ecthyma (CE) in small ruminants. It is an endemic disease on goat and sheep herds around the world. It is often a neglected disease, with impacts on herd health and productivity, while also being an occupational zoonosis. This review explores the causative agent of ovine ecthyma, its epidemiology, and clinical manifestations, with a particular emphasis on its interaction with the host's immune system and the development of ORFV vaccines. Like other members of the Poxviridae family, ORFV expresses numerous immunomodulatory genes, which complicate vaccination efforts and disease management. This review highlights the challenges posed by ORFV in achieving effective immunization and discusses potential vaccine strategies to overcome these obstacles.

Effects of chemokine-binding protein in visceral ovine aphthae on immune regulation response

ORFV of the family poxvirus，which produces a pustular dermatitis both in humans and animals.,Previous studies have found an fatal case caused by the infection of ORFV in the viscera. However, the mechanisms of ORFV how to infect the viscera remain unknown. Our sequencing results revealed that the CBP of the visceral infection strain lacked a 24-base pair segment at position 217 comparison to the oral infection strain. Subsequently, we successfully packaged the recombinant adenoviruses pAd-CBP-K and pAd-CBP-N in HEK-293A cells and carried it to infect lymphocytes. RT-PCR analysis showed that the CBP protein was expressed in lymphocytes, and pAd-CBP-N group exhibited a significantly higher CBP expression level compared to the pAd-CBP-K group. At 4, 8, and 12 hours post-infection, both pAd-CBP-K and pAd-CBP-N were found to downregulate the expression of MIP-1 and CCL-5 in the supernatant of lymphocytes. However, the expression of IL-2, IL-6, IL-8, IL-12, INF-γ, and TNF-α showed a significant up-regulation. Furthermore, the inflammatory factors relative expression levels of IL-2, IL-6, IL-8, IL-8, IL-12, IFN-γ and TNF-α were significantly up-regulated in the both group. Interestingly, a significant increase in the expression of IL-6, IL-8 and TNF-α were detected in the pAd-CBP-N group at both 8 and 12 hours compared to pAd-CBP-N. Taken together, these findings showed that CBP can regulate the expression of free chemokines and activate the expression of inflammatory factors, and provide a basis for follow-up 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.

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.

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.

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.

Poxviral E3L ortholog (Viral Interferon resistance gene) of orf viruses of sheep and goats indicates species-specific clustering with heterogeneity among parapoxviruses

Orf is a contagious disease posing a serious threat to animal and human health. E3L is one of the evolutionarily acquired immunomodulatory proteins present in orf virus (ORFV) and is responsible for conferring resistance to interferons among poxviruses. Genetic analysis of ORFV isolates of different geographical regions including Indian subcontinent targeting viral interferon resistance (VIR) gene (a homolog of vaccinia virus E3L gene) revealed a high percentage of identity among themselves and other ORFV isolates at both nt and aa levels as compared to low identity among parapoxviruses (PPVs). Phylogenetic analysis showed species-specific clustering among PPVs along with sub-clusters based on host species of origin among ORFVs infecting sheep and goats. Conserved amino acids in N-terminal Z-DNA binding domain and C-terminal ds RNA binding domain of VIR proteins of PPVs corresponding to ORFV VIR positions namely N37, Y41, P57, and W59 (necessary for Z-DNA binding) and E116, F127, F141, and K160 (necessary for dsRNA binding) were found. Further, the predicted protein characteristics and homology model of VIR protein of ORFV showed high structural conservation among poxviruses. This study on E3L genetic analysis of ORFV isolates may provide a better understanding of the molecular epidemiology of circulating strains in India and neighboring countries. Also, E3L deleted or mutated ORFV may be an as vaccine candidate and/or compounds blocking E3L may prove as an effective method for treating broad spectrum poxviral infections, suggesting a wider application in control of poxvirus infections.

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.

Dermatopathology of Orf Virus (Malaysian Isolates) in Mice Experimentally Inoculated at Different Sites with and without Dexamethasone Administration

Orf is a clinical manifestation of parapoxvirus infection often fatal in goats and sheep especially when they are under stress or influenced by unfavorable environment. This study investigated the pathogenicity of two Orf virus isolates (ORFV UPM1/14 and UPM2/14) and host response in mouse model by using different inoculation sites with/without prior exposure to dexamethasone. Treatments with dexamethasone served as an immunosuppressant that may mimic stress situation in affected animals. Groups of five mice were given intradermal injection of 0.2 mL of tissue culture infective dose 50 (TCID₅₀) of UPM1/14 (Group 1) and UPM2/14 (Group 2) at the dorsum (Group 1A; Group 2A), ear pinna (Group 1B; Group 2B), and labial commissure (Group 1C; Group 2C). An inoculum 0.2 mL of UPM1/14 was administered to animals treated with dexamethasone (n=5; 5 mg/kg/day intraperitoneally) and nondexamethasone (n=5) groups at the dorsum, ear pinna, and labial commissure. No significant difference (p>0.05) was observed in the mean lesion scores among the groups of different inoculation sites or between dexamethasone-treated and nontreated groups. However, there was a significant difference (p<0.05) in the mean stratum thickness of affected skin following inoculation with UPM2/14 isolate at the ear pinna and labial commissure. Histopathology examination revealed keratosis, acanthosis, and ballooning degeneration in the skin of affected mice. Orf virus DNA was detected in the skin samples by targeting F1L and B2L virus-specific genes in polymerase chain reaction (PCR) assay. Intradermal inoculation with UPM1/14 or UPM2/14 isolate produced a mild skin lesion in mice, and there was no significant difference in orf disease manifestation despite variation of inoculation sites. Similarly, short-term dexamethasone administration gave no adverse effects on pathogenicity of orf virus isolates.

Phylogenetic Analysis of ORF Viruses From Five Contagious Ecthyma Outbreaks in Argentinian Goats

Orf virus (ORFV) is the etiological agent of Contagious Ecthyma (CE) disease that mainly affects sheep, goats, wild ruminants, and humans with a worldwide distribution. To date, only two strains from Argentinian sheep have been characterized at the molecular level and there is little information on ORFV strains circulating in Argentina. Here we describe and analyze five outbreaks of CE in goats in three geographic regions of the country: Northwest, Center, and Southwest. The phylogenetic analysis based on four molecular markers of ORFV (orf011 partial sequence and orf020, orf109, and orf127 complete sequence genes) revealed that there are different strains circulating in Argentina and pointed out the importance of knowing the health status of animals traded between farms.

The re-emerging of orf virus infection: A call for surveillance, vaccination and effective control measures

Orf disease is known to be enzootic among small ruminants in Asia, Africa, and some other parts of the world. The disease caused by orf virus is highly contagious among small ruminant species. Unfortunately, it has been neglected for decades because of the general belief that it only causes a self-limiting disease. On the other hand, in the past it has been reported to cause huge cumulative financial losses in livestock farming. Orf disease is characterized by localized proliferative and persistent skin nodule lesions that can be classified into three forms: generalized, labial and mammary or genitals. It can manifest as benign or malignant types. The later type of orf can remain persistent, often fatal and usually causes a serious outbreak among small ruminant population. Morbidity and mortality rates of orf are higher especially in newly infected kids and lambs. Application of antibiotics together with antipyretic and/or analgesic is highly recommended as a supportive disease management strategy for prevention of subsequent secondary microbial invasion. The presence of various exotic orf virus strains of different origin has been reported in many countries mostly due to poorly controlled cross-border virus transmission. There have been several efforts to develop orf virus vaccines and it was with variable success. The use of conventional vaccines to control orf is a debatable topic due to the concern of short term immunity development. Following re-infection in previously vaccinated animals, it is uncommon to observe the farms involved to experience rapid virus spread and disease outbreak. Meanwhile, cases of zoonosis from infected animals to animal handler are not uncommon. Despite failures to contain the spread of orf virus by the use of conventional vaccines, vaccination of animals with live orf virus is still considered as one of the best choice. The review herein described pertinent issues with regard to the development and use of potential effective vaccines as a control measure against orf virus infection.

Genetic variation and diversity in 199 Melilotus accessions based on a combination of 5 DNA sequences

Melilotus is an important genus of legume plants and an herbage with excellent nitrogen fixation; it can tolerate extreme environmental conditions and possesses important medicinal value. However, there is limited genetic information about the genus; thus, we analysed four chloroplast loci (rbcL, matK, psbA-trnH and trnL-F) and one nuclear region (ITS) to determine the genetic diversity of 199 accessions from 18 Melilotus species. The rbcL and matK sequences were highly conserved, whereas the trnL-F and ITS sequences contained variable and parsimony-informative sites. In our analyses of the single and combined regions, we calculated the pairwise distance, haplotype and nucleotide diversity and gaps and then constructed phylogenetic trees to assess the genetic diversity, and our results revealed significant variations among the different accessions. The genetic distance values were between zero and nine, and based on the combined regions, the highest frequency value was approximately four. Melilotus showed high haplotype and nucleotide diversity, particularly in the ITS sequences, with values of 0.86 and 0.0087, respectively. The single ITS sequence, psbA-trnH, and the combined matK+rbcL+trnL-F (MRT) and matK+rbcL+psbA-trnH+trnL-F+ITS (MRPTI) regions showed interspecific variation in the gap analysis. Phylogenetic trees calculated using ITS, psbA-trnH and MRPTI sequences indicated distinct genetic relationship in 18 species, and these species could be divided into two groups. By determining the genetic diversity of plants, we can evaluate the genetic relationships among species and accessions, providing a basis for preserving and utilizing the genetic resources of Melilotus.

Genetic diversity of Orf virus isolated from sheep in Uruguay

Orf virus (ORFV) is the etiological agent of contagious ecthyma, a disease widely spread in the world that occasionally causes zoonotic infections. This work is the first molecular characterization of ORFV in Uruguay, where we analyzed twenty-one sheep samples, eighteen of which were recovered from thirteen ORFV outbreaks that occurred during 2004 to 2011 as well as three strains from a national vaccine. Phylogenetic analysis and the derived amino acid sequences from the B2L gene suggest that the Uruguayan virus do not form a unique cluster, with most of them displaying similarities with worldwide ORFV isolates as well as our vaccine strains.

Molecular identification and investigations of contagious ecthyma (Orf virus) in small ruminants, North west Ethiopia

Background

Orf virus, the prototype of parapoxvirus, is the main causative agent of contagious ecthyma. Little is known about the status of the disease in Ethiopia and this study was aimed at determining its status using PCR as a confirmatory tool.

Methods

a total of 400 randomly selected sheep and goat was screened for the identification of the virus using amplification of B2L gene and transfection of mammalian cells (VERO cells).

Results

Out of 400 animals screened for infection of the virus, 48 animals were found positive to PCR and revealed an overall incidence of 12%. Different epidemiological parameters were considered to look at the association with incidence of the disease and of which, only species of the animal(sheep), non-vaccinated and non-treated animals, nursing animals, poor body condition animals, extensively managed animals, animals having mouth lesion, and study areas having outbreak history showed higher prevalence. A univariate logistic regression analysis showed statistically significant difference in all variables (P < 0.05). Whereas, age and sex of animals showed no significant difference (P < 0.05).

Conclusion

The result of the present finding showed high incidence of Orf virus in the region as confirmed through PCR.

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.