Surveillance of parapoxvirus among ruminants in Virginia and Connecticut

Cross-species transmission and host range genes in poxviruses

The persistent epidemic of human mpox, caused by mpox virus (MPXV), raises concerns about the future spread of MPXV and other poxviruses. MPXV is a typical zoonotic virus which can infect human and cause smallpox-like symptoms. MPXV belongs to the Poxviridae family, which has a relatively broad host range from arthropods to vertebrates. Cross-species transmission of poxviruses among different hosts has been frequently reported and resulted in numerous epidemics. Poxviruses have a complex linear double-strand DNA genome that encodes hundreds of proteins. Genes related to the host range of poxvirus are called host range genes (HRGs). This review briefly introduces the taxonomy, phylogeny and hosts of poxviruses, and then comprehensively summarizes the current knowledge about the cross-species transmission of poxviruses. In particular, the HRGs of poxvirus are described and their impacts on viral host range are discussed in depth. We hope that this review will provide a comprehensive perspective about the current progress of researches on cross-species transmission and HRG variation of poxviruses, serving as a valuable reference for academic studies and disease control in the future.

Bovine papular stomatitis virus as a vaccine vector for cattle

Virus vectored vaccines are not available commercially for cattle even though compelling potential applications exist. Bovine papular stomatitis virus (BPSV), a highly prevalent parapoxvirus, causes self-limited oral lesions in cattle. Ability of virus to accommodate large amounts of foreign DNA, induce low level of antiviral immunity, and circulate and likely persist in cattle populations, make BPSV an attractive candidate viral vector. Here, recombinant BPSV were constructed expressing either Bovine herpesvirus 1 (BoHV-1) glycoprotein gD (BPSVgD), or gD and gB (BPSVgD/gB). Immunization of BPSV serologically-positive calves with BPSVgD or BPSVgD/gB induced BoHV-1 neutralization antibodies and provided protection for three of four animals following a high dose BoHV-1 challenge at day 70 pi. Results indicate BPSV suitability as a candidate virus vector for cattle vaccines.

Possibility of mechanical transmission of parapoxvirus by houseflies (Musca domestica) on cattle and sheep farms

Parapoxvirus (PPV) causes papular stomatitis and contagious pustular dermatitis in ruminants worldwide. The virus is generally transmitted through close contact with skin lesions containing PPV in infected animals and indirectly through PPV-contaminated materials. PPV-infected animals frequently do not show clinical signs and the route of PPV transmission is sometimes unclear. In this study, the possibility of mechanical transmission of PPV by houseflies (Musca domestica) was investigated using polymerase chain reaction (PCR) gene surveillance. Samples were collected from cattle, sheep, barn environments, direct wash solution of the body surface of houseflies, and indirect wash solution of the body surface and feces of the flies. Bovine papular stomatitis virus, pseudocowpox virus, and orf virus were detected in the oral cavity and body surface of cattle and sheep without clinical signs of PPV infection or barn environments; PPV was considered to have been retained on the farm. PPVs were also detected in the direct wash solution of the body surface of houseflies, and the indirect wash solution of the body surface and feces of the flies. The viral sequence determined from the indirect wash solution of the body surface and feces of the flies was identical to that determined from the body surface of cattle and barns. These results suggested that houseflies may mechanically transmit PPV to both cattle and sheep.

Food Safety Considerations Related to the Consumption and Handling of Game Meat in North America

Emerging foodborne pathogens present a threat to public health. It is now recognized that several foodborne pathogens originate from wildlife as demonstrated by recent global disease outbreaks. Zoonotic spillover events are closely related to the ubiquity of parasitic, bacterial, and viral pathogens present within human and animal populations and their surrounding environment. Foodborne diseases have economic and international trade impacts, incentivizing effective wildlife disease management. In North America, there are no food safety standards for handling and consumption of free-ranging game meat. Game meat consumption continues to rise in North America; however, this growing practice could place recreational hunters and game meat consumers at increased risk of foodborne diseases. Recreational hunters should follow effective game meat food hygiene practices from harvest to storage and consumption. Here, we provide a synthesis review that evaluates the ecological and epidemiological drivers of foodborne disease risk in North American hunter populations that are associated with the harvest and consumption of terrestrial mammal game meat. We anticipate this work could serve as a foundation of preventive measures that mitigate foodborne disease transmission between free-ranging mammalian and human populations.

qPCR assay for the detection of pseudocowpox virus

Pseudocowpox is a zoonosis caused by pseudocowpox virus (PCPV), which mainly affects cows but can be an occupational disease of humans. The aim of the study was to validate a quantitative polymerase chain reaction (qPCR) assay for the detection of PCPV. The assay was able to detect up to 1000 copies of PCPV per µL in field samples, with a sensitivity of 80% and a specificity of 100%. We did not observe any cross-reactivity between PCPV-positive samples and samples that were positive for other genetically similar viruses. The repeatability and reproducibility were adequate according to parameters preestablished in official test validation manuals.

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.

First detection and molecular characterisation of pseudocowpox virus in a cattle herd in Zambia

Background

Pseudocowpox virus (PCPV) of the genus Parapoxvirus in the family Poxviridae causes pseudocowpox in cattle worldwide and presents a zoonotic concern. Most poxviruses produce diseases of similar clinical signs in affected animals, which are impossible to differentiate clinically or by serology. It is, therefore, vital to use molecular assays to rapidly identify the causative agents of poxvirus infections. This study aimed to detect, diagnose, and characterize the causative agent of pox-like skin lesions in a cattle herd in Zambia, initially suspected to be infected with Lumpy Skin Disease virus.

Methods

We used a High-Resolution Melting (HRM) analysis assay to detect the PCPV genome and sequenced the major envelope protein (B2L gene) for comparative sequence and phylogenetic analysis.

Results

Our field investigations showed cattle presenting atypical skin lesions and high morbidity within the herd. The laboratory diagnosis, based on the HRM assay revealed PCPV DNA in the samples. Phylogenetic and comparative sequence analyses confirmed PCPV in the samples and revealed genomic differences between samples collected in 2017 and 2018 from the same farm.

Conclusion

Our work is the first documented report of PCPV in Zambia. It shows the strength of molecular methods to diagnose pox-like infections in cattle and discriminate between diseases causing similar clinical signs. This rapid and accurate diagnosis improves the response time for more accurate veterinary interventions.

Epitheliotropic Infections in Wildlife Ruminants From the Central Alps and Stelvio National Park

The mountain chain of the Alps, represents the habitat of alpine fauna where the red deer (Cervus elaphus) population is the outmost numerous, followed by the chamois (Rupicapra rupicapra) and the alpine ibex (Capra ibex) at higher altitudes. Previous reports showed the circulation of epitheliotropic viruses, belonging to the families Papillomaviridae and Poxviridae, causing skin and mucosal lesions in wild ruminants of the Stelvio National Park, situated in the area. To deepen our knowledge on the natural dynamics of the infections, a passive surveillance on all the cases of proliferative skin and mucosal lesions in wild ruminants was performed. Twenty-seven samples (11 chamois, 10 red deer and 6 ibex) collected from 2008 to 2018 were analyzed by negative staining electron microscopy, histology, and PCR followed by genome sequencing and phylogenetic analyses. Results confirmed the spread of Parapoxvirus of Red Deer in New Zealand (PVNZ) in Italy, and its ability to cause severe lesions i.e., erosions and ulcers in the mouth. We showed for the first time a PVNZ/CePV1v (C. elaphus papillomavirus 1 variant) co-infection identified in one red deer. This result supports previous evidence on the ability of papillomavirus and parapoxvirus to mutually infect the same host tissue. Interestingly two ibex and one chamois showing orf virus (OV) skin lesions were shown to be co-infected with bovine papillomavirus type 1 and 2. The presence of bovine papillomavirus, in orf virus induced lesions of chamois and ibex raises the question of its pathogenetic role in these animal species. For the first time, OV/CePV1v co-infection was demonstrated in another chamois. CePV1v is sporadically reported in red deer throughout Europe and is considered species specific, its identification in a chamois suggests its ability of cross-infecting different animal species. Poxviruses and papillomavirus have been simultaneously detected also in the skin lesions of cattle, bird and human suggesting a possible advantageous interaction between these viruses. Taken together, our findings add further information on the epidemiology and pathogenetic role of epitheliotropic viruses in wild ruminants living in the central Alps and in Stelvio National Park.

Late development of pustular, erosive lesions in the muzzle of calves inoculated with Pseudocowpox virus

We studied the pathogenesis of Pseudocowpox virus (PCPV), a zoonotic parapoxvirus associated with mucocutaneous lesions in cattle. Inoculation of calves with PCPV isolate SD 76-65 intranasally (n = 6) or transdermally in the muzzle (n = 2) resulted in virus replication and shedding up to day 13 post-infection (pi). No local or systemic signs were observed in inoculated calves up to day 20pi, when the clinical monitoring was discontinued. However, from days 28-34 pi, seven (7/8) inoculated calves underwent an asynchronous clinical course characterized by development of a few (one or two) to countless papulo-pustular, erosive-fibrinous and scabby lesions in the muzzle, in some cases extending to the lips and gingiva. In some animals, the lesions coalesced, forming extensive fibrinotic/necrotic and scabby plaques covering almost entirely the muzzle. The clinical course lasted 8-15 days and spontaneously subsided after day 42pi. Infectious virus and/or viral DNA were detected in swabs collected from lesions of 5/8 animals between days 34 and 42pi. Histological examination of fragments collected from the muzzle lesions of two affected calves (day 36pi) revealed marked epidermal hyperplasia and severe orthokeratotic and parakeratotic hyperkeratosis, covered by thick scabs. The epidermis showed multifocal areas of keratinocyte coalescing necrosis and mild multifocal vacuolar degeneration. Sera of inoculated calves at 50pi showed partial virus neutralization at low dilutions, demonstrating seroconversion. The delayed and severe clinical course associated with virus persistence in lesions are novel findings and contribute for the understanding of PCPV pathogenesis.

Putative parapoxvirus-associated foot disease in the endangered huemul deer (Hippocamelus bisulcus) in Bernardo O'Higgins National Park, Chile

The huemul (Hippocamelus bisulcus) is an endangered cervid endemic to southern Argentina and Chile. Here we report foot lesions in 24 huemul from Bernardo O’Higgins National Park, Chile, between 2005 and 2010. Affected deer displayed variably severe clinical signs, including lameness and soft tissue swelling of the limbs proximal to the hoof or in the interdigital space, ulceration of the swollen tissues, and some developed severe proliferative tissue changes that caused various types of abnormal wear, entrapment, and/or displacement of the hooves and/or dewclaws. Animals showed signs of intense pain and reduced mobility followed by loss of body condition and recumbency, which often preceded death. The disease affected both genders and all age categories. Morbidity and mortality reached 80% and 40%, respectively. Diagnostics were restricted to a limited number of cases from which samples were available. Histology revealed severe papillomatous epidermal hyperplasia and superficial dermatitis. Electron microscopy identified viral particles consistent with viruses in the Chordopoxvirinae subfamily. The presence of parapoxvirus DNA was confirmed by a pan-poxvirus PCR assay, showing high identity (98%) with bovine papular stomatitis virus and pseudocowpoxvirus. This is the first report of foot disease in huemul deer in Chile, putatively attributed to poxvirus. Given the high morbidity and mortality observed, this virus might pose a considerable conservation threat to huemul deer in Chilean Patagonia. Moreover, this report highlights a need for improved monitoring of huemul populations and synergistic, rapid response efforts to adequately address disease events that threaten the species.

Development and validation of a highly sensitive real-time PCR assay for rapid detection of parapoxviruses

Parapoxviruses (PaPVs) cause widespread infections in ruminants worldwide. All PaPVs are zoonotic and may infect humans after direct or indirect contact with infected animals. Herein we report the development and validation of a highly sensitive real-time PCR assay for rapid detection of PaPVs. The new assay (referred to as the RVSS assay) was specific for PaPVs only and had no cross-reactivity against other pox viruses. Using a recombinant plasmid as positive control, the analytical sensitivity of the assay was determined to be 16 genome copies of PaPV per assay. The amplification efficiency estimate (91–99%), the intra- and interassay variability estimate (standard deviation [SD]: 0.28–1.06 and 0.01–0.14, respectively), and the operator variability estimate (SD: 0.78 between laboratories and 0.28 between operators within a laboratory) were within the acceptable range. The diagnostic specificity was assessed on 100 specimens from healthy normal animals and all but 1 tested negative (99%). The diagnostic sensitivity (DSe) was assessed on 77 clinical specimens (skin/scab) from infected sheep, goats, and cattle, and all tested positive (100%). The assay was multiplexed with beta-actin as an internal positive control, and the multiplex assay exhibited the same DSe as the singleplex assay. Further characterization of the PaPV specimens by species-specific real-time PCR and nucleotide sequencing of the PCR products following conventional PCR showed the presence of Orf virus not only in sheep and goats but also in 1 bovid. The validated RVSS assay demonstrated high specificity, sensitivity, reproducibility, and ruggedness, which are critical for laboratory detection of PaPVs.

Detection and quantification of parapoxvirus DNA by use of a quantitative real-time polymerase chain reaction assay in calves without clinical signs of parapoxvirus infection

OBJECTIVE

To investigate the presence of parapoxvirus (PPV) in cattle without clinical signs of infection and in farm environments of PPV-infected cattle.

ANIMALS

28 calves without clinical signs of PPV infection on 2 farms and 11 clinically affected calves on 6 farms.

PROCEDURES

164 oral swab samples were collected at regular intervals from 28 calves without clinical signs of PPV infection, and 11 swab samples were collected from 11 clinically affected calves. Viral DNA load was quantified by use of a PPV-specific quantitative real-time PCR (qRT-PCR) assay. RESULTS Of 28 calves without clinical signs of PPV infection, 12 had positive results for PPV DNA by use of the qRT-PCR assay. Viral DNA was detected continuously over a period of 2 to 5 months from 9 of these 12 calves, particularly from calves with dermatomycosis or respiratory tract disease. The PPV DNA loads in 32 oral swab samples from these 12 calves were significantly lower (median, 3.2 copies/mg) than those in samples collected from the 11 clinically affected calves (median, 3.2 × 10(4) copies/mg). Moreover, PPV DNA was detected in the residual feed and drinking water on both farms that housed the calves without clinical signs of PPV infection.

CONCLUSIONS AND CLINICAL RELEVANCE

PPV in cattle without clinical signs of infection and in the environments of these cattle may represent sources of PPV transmission to susceptible cattle.

IMPACT FOR HUMAN MEDICINE

Humans should wear gloves to prevent zoonotic disease transmission when handling cattle with or without clinical signs of PPV infection.

A Broad-Spectrum Chemokine-Binding Protein of Bovine Papular Stomatitis Virus Inhibits Neutrophil and Monocyte Infiltration in Inflammatory and Wound Models of Mouse Skin

Bovine papular stomatitis virus (BPSV) is a Parapoxvirus that induces acute pustular skin lesions in cattle and is transmissible to humans. Previous studies have shown that BPSV encodes a distinctive chemokine-binding protein (CBP). Chemokines are critically involved in the trafficking of immune cells to sites of inflammation and infected tissue, suggesting that the CBP plays a role in immune evasion by preventing immune cells reaching sites of infection. We hypothesised that the BPSV-CBP binds a wide range of inflammatory chemokines particularly those involved in BPSV skin infection, and inhibits the recruitment of immune cells from the blood into inflamed skin. Molecular analysis of the purified protein revealed that the BPSV-CBP is a homodimeric polypeptide with a MW of 82.4 kDa whilst a comprehensive screen of inflammatory chemokines by surface plasmon resonance showed high-affinity binding to a range of chemokines within the CXC, CC and XC subfamilies. Structural analysis of BPSV-CBP, based on the crystal structure of orf virus CBP, provided a probable explanation for these chemokine specificities at a molecular level. Functional analysis of the BPSV-CBP using transwell migration assays demonstrated that it potently inhibited chemotaxis of murine neutrophils and monocytes in response to CXCL1, CXCL2 as well as CCL2, CCL3 and CCL5 chemokines. In order to examine the effects of CBP in vivo, we used murine skin models to determine its impact on inflammatory cell recruitment such as that observed during BPSV infection. Intradermal injection of BPSV-CBP blocked the influx of neutrophils and monocytes in murine skin in which inflammation was induced with lipopolysaccharide. Furthermore, intradermal injection of BPSV-CBP into injured skin, which more closely mimics BPSV lesions, delayed the influx of neutrophils and reduced the recruitment of MHC-II+ immune cells to the wound bed. Our findings suggest that the CBP could be important in pathogenesis of BPSV infections.

Coinfection with multiple strains of bovine papular stomatitis virus

Bovine papular stomatitis virus (BPSV) infects cattle and, occupationally, humans. Prevalent subclinical infections, frequent reinfections, and virus persistence in healthy animals compound a poorly understood, but likely complex, scenario of BPSV perpetuation and transmission in nature. Here, we report the isolation of multiple BPSV strains coinfecting a single animal. Whole-genome analysis of isolated BPSV strains revealed genomic variability likely affecting virus virulence and infectivity. Further, incongruent phylogenetic relationships between viruses suggested genomic recombination. These results have significant implications for parapoxvirus infection biology and virus evolution in nature.

Zoonotic parapoxviruses detected in symptomatic cattle in Bangladesh

Background

Application of molecular diagnostic methods to the determination of etiology in suspected poxvirus-associated infections of bovines is important both for the diagnosis of the individual case and to form a more complete understanding of patterns of strain occurrence and spread. The objective of this study was to identify and characterize bovine-associated zoonotic poxviruses in Bangladesh which are relevant to animal and human health.

Findings

Investigators from the International Center Diarrhoeal Disease Research (icddr,b), the US Centers for Disease Control and Prevention (CDC), and the Bangladesh Department of Livestock Services traveled to three districts in Bangladesh—Siranjganj, Rangpur and Bhola–to collect diagnostic specimens from dairy cattle and buffalo that had symptoms consistent with poxvirus-associated infections. Bovine papular stomatitis virus (BPSV) DNA was obtained from lesion material (teat) and an oral swab collected from an adult cow and calf (respectively) from a dairy production farm in Siranjganj. Pseudocowpox virus (PCPV) DNA signatures were obtained from a scab and oral swab collected from a second dairy cow and her calf from Rangpur.

Conclusions

We report the first detection of zoonotic poxviruses from Bangladesh and show phylogenetic comparisons between the Bangladesh viruses and reference strains based on analyses of the B2L and J6R loci (vaccinia orthologs). Understanding the range and diversity of different species and strains of parapoxvirus will help to spotlight unusual patterns of occurrence that could signal events of significance to the agricultural and public health sectors.