Swinepox Research Articles

Swinepox virus: an unusual outbreak in free-range pig farms in Sicily (Italy)

BackgroundTwo outbreaks of swinepox were investigated in free-range domestic pig farms located in the northeastern side of Sicily, Italy. The disease is generally self-limiting with a low mortality rate, but morbidity can reach high rates in case of poor sanitary conditions, improper husbandry practices and ectoparasitic infestation. The presented cases are the first ever reported on the island and part of the few cases reported in domestic pigs.Case presentationCarcasses condemned at the slaughterhouse and deceased pigs from Farm A and Farm B respectively, were referred for post-mortem examination and further investigations, with a strong suspect of SwinePox virus (SWPV) infection. Twelve deceased pigs were examined in total, showing poor body condition and pustular lesions scattered all over the cutaneous surfaces. Moreover, pigs from Farm B showed ocular lesions classified from Grade I to IV (from mild conjunctivitis to severe keratoconjunctivitis with corneal oedema, opacity, and ulcers). Final diagnosis was pursued by the microscopic assessment of skin lesions in both farms, which revealed the typical SWPV-lesion appearance, such as severe and disseminated ulcerative dermatitis and suspected inclusion bodies multifocally observed in the epidermis. Moreover, negative staining Electron Microscopy (nsEM) was performed on skin lesions and ocular swabs from Farm B, revealing in two samples the presence of brick-shaped viral particles, 220 nm long and 160 nm wide, with irregularly arranged surface tubules, identified as SWPV. The gene encoding the 482-bp fragment of the virus late transcription factor–3 was detected by PCR and sequencing revealed 99.79% identity and 100% query-cover with a strain previously isolated in Germany. Field clinical assessment was then performed in Farm B, revealing high overcrowding, poor sanitary conditions and improper husbandry practices, which are relevant risk factors for SWPV transmission.ConclusionsThe present is the first case report of SWPV in free-range pigs raised in Sicily, an island of the Southern coast of Italy, and wants to raise awareness on a neglected disease, and cause of animal health and welfare issues.

Co-Circulating Monkeypox and Swinepox Viruses, Democratic Republic of the Congo, 2022

Co-Circulating Monkeypox and Swinepox Viruses, Democratic Republic of the Congo, 2022

Construction and identification of recombinant swinepox virus expressing p72 protein of African swine fever virus

Construction and identification of recombinant swinepox virus expressing p72 protein of African swine fever virus

Viability of Veterinary-Relevant Viruses in Decomposing Tissues over a 90-Day Period Using an In-Vitro System.

Depopulation is frequently employed during outbreaks of high-impact animal diseases. Security breaches in sites managing mortality may jeopardize pathogen control efforts as infected carcasses can serve as an infection source. This study evaluated the viability and nucleic acid detection of veterinary-relevant viruses or their surrogates in decomposing tissues. The used viruses were: Senecavirus A1 (SVA), feline calicivirus (FCV), bovine viral diarrhea virus (BVDV), porcine epidemic diarrhea virus (PEDV), bovine alphaherpesvirus 1 (BoHV-1), and swinepox virus (SwPV). Viruses were spiked in three decomposing tissues (swine bone marrow and spleen, and bovine bone marrow) and maintained for 90 days. Samples were kept under two temperature conditions resembling the average soil temperature in central Oklahoma, US, during the winter and summer (5.5 °C and 29.4 °C). At 5.5 °C, SVA and FCV remained viable over the 90 days of the study, followed by BVDV (75 days), BoHV-1 and SwPV (60 days), and PEDV (10 days). At 29.4 °C, SVA remained viable for 45 days, followed by BVDV and BoHV-1 (14 days). SwPV was viable for 10 days, whereas FCV and PEDV were viable for 5 days. Overall, viral nucleic acid detection was not significantly altered during the study. These findings support decision-making and risk management in sites overseeing animal mortality.

Isolation and Characterization of Swinepox Virus from Outbreak in Russia.

Swinepox virus (SWPV) is the only member of the Suipoxvirus genus of the Poxviridae family and is an etiologic agent of a worldwide disease specific for domestic and wild pigs. SWPV outbreaks are sporadically recorded in different regions of Russia. In 2013, an outbreak of the disease causing skin lesions was registered on a pig farm in Russia. The presence of SWPV in the scab samples was assessed by in-house real-time PCR, reference PCR amplification, and nucleotide sequencing of the viral late transcription factor-3 (VLTF-3) gene and was then confirmed by virus isolation. Thus, the in-house real-time PCR proposed in this study could serve as a useful tool for the rapid specific detection of the swinepox virus. In the study, it has been demonstrated for the first time that nasal and oral swabs can be used for PCR diagnosis of the disease and for swinepox virus isolation. Phylogenetic analysis revealed that the isolated virus was closely related to SWPV isolates registered in Germany, USA, and Brazil, and slightly differed from the Indian isolates. During experimental infection of pigs, a low pathogenicity of the Russian isolate was observed. Our data provides the first report on the isolation and characterization of swinepox virus in Russia.

First Report of Swinepox in a Wild Boar in Italy: Pathologic and Molecular Findings.

Swinepox virus (SWPV) is responsible for sporadic acute poxvirus infections in swine worldwide, causing a pathognomonic eruptive proliferative dermatitis. Beside direct and congenital transmission, the pig louse Haematopinus suis acts as a mechanical vector and favors virus infection through skin lesions. Infections are generally described in domestic pigs, while only a few cases have been reported in wild boars, in Austria and Germany. In September 2022, SWPV infection was suspected at post-mortem examination of a wild boar piglet with characteristic lesions in Liguria, Northwest Italy. The piglet was heavily parasitized by swine lice (H. suis). SWPV was then confirmed by histological and molecular analyses. Possible viral co-infections were also investigated (African swine fever virus, classical swine fever virus, parvovirus, circovirus, Aujeszky's disease virus and hepatitis E virus). This article describes gross and histopathologic features of SWPV infection, differential diagnosis, and potential vector-borne transmission to domestic pigs, presenting a brief review of the literature on the topic. SWPV infection is reported in wild boars in Italy for the first time. The finding of SWPV in a wild boar in an area with a very limited pig population may suggest the existence of a "wildlife cycle" in the area. Further investigations are needed to understand the real risk of transmission of SWPV to domestic pigs as well as the role of other arthropod vectors.

‘NanoViroSan’ antimicrobial composite, designed for emergency epizootic situations and safe usage in ecological pig farming

Analytical data of preclinical and clinical trials of the experimental veterinary composite drug ‘NanoViroSan’ (containing Methisazone, Silgeran and magnesium nanooxide) on laboratory models of Aujeszky’s (AD) and Teschen (TD) diseases, circovirus infections (PCV 2) and actinobacillary pleuropneumonia (APP) as well as in enzootic foci of mixed infection of AD-PCV-APP and swine pox, are presented, respectively. At the level of statistical probability p ≤ 0.01–0.03 (n = 88), the absence of cytotoxic (n = 40, cultures of pig testicle cells and pig alveolar macrophages) and biotoxic effects (n = 48 guinea pigs) was proven, as well as high antimicrobial (viro- and bacteriostatic) activity of the drug in the concentration range (by Methisazone) of 1.0–4.0 mg/cm3. Intramuscular administration of the drug to male pedigree piglets in doses of 0.5 cm3/20 kg and 1.5 cm3/20 kg three times with an interval of a day made it possible to stop the carriage of the causative agents of mixed infection in the conditions of pig-breeding (n = 26, p ≤ 0.02). Similar treatment with the drug in a dose of 2 cm3/20 kg (by Methisazone) of a boar and five sows in another commodity farm made it possible to break the chain of vertical transmission of the causative agent of swine pox from the nucleus to offspring of the herd (n = 227, p ≤ 0.03). There conclusion was made regarding the perspective of experimental drug for bioprotection of pig farming in the conditions of martial law, as well, if additional research will be positive — as for the development of permaculture (‘green technologies’) in the field of pig breeding

The recombinant swinepox virus expressing sseB could provide piglets with strong protection against Salmonella typhimurium challenge

Salmonella spp. poses a great threat to the livestock, food safety and public health. A recombinant swinepox virus expressing a protective antigen sseB was constructed by homologous recombination to develop a vaccine against Salmonella infection. The rSPV-sseB was verified using PCR, Western blot and indirect immunofluorescence assay. The immune responses and protective efficacy of rSPV-sseB were assessed in piglets. Forty piglets were immunized with rSPV-sseB, inactive Salmonella vaccine, wild-type SPV (wtSPV), or PBS. The results showed that the level of the sseB-specific antibody of the rSPV-sseB-vaccinated piglets was significantly higher at all time points post-vaccination than those of the inactivated Salmonella vaccine (P < 0.05), wtSPV (P < 0.001) or mock treated piglets (P < 0.001). The IL-4 and IFN-γ in the rSPV-sseB group were significantly higher than the other three groups at all post-infection time points. rSPV-sseB provided piglets with strong protection against the challenge of S. typhimurium with lethal dose. These results suggest the possibility of using recombinant swinepox virus rSPV-sseB as a promising vaccine to prevent Salmonella infection.

Rabbit hemorrhagic disease virus VP60 protein expressed in recombinant swinepox virus self-assembles into virus-like particles with strong immunogenicity in rabbits.

Rabbit Hemorrhagic Disease (RHD) is an economically significant infectious disease of rabbits, and its infection causes severe losses in the meat and fur industry. RHD Virus (RHDV) is difficult to proliferate in cell lines in vitro, which has greatly impeded the progress of investigating its replication mechanism and production of inactivated virus vaccines. RHDV VP60 protein is a major antigen for developing RHD subunit vaccines. Herein, we constructed a TK-deactivated recombinant Swinepox virus (rSWPV) expressing VP60 protein and VP60 protein coupled with His-tag respectively, and the expression of foreign proteins was confirmed using immunofluorescence assay and western blotting. Transmission electron microscopy showed that the recombinant VP60, with or without His-tag, self-assembled into virus-like particles (VLPs). Its efficacy was evaluated by comparison with available commercial vaccines in rabbits. ELISA and HI titer assays showed that high levels of neutralizing antibodies were induced at the first week after immunization with the recombinant strain and were maintained during the ongoing monitoring for the following 13 weeks. Challenge experiments showed that a single immunization with 106 PFU of the recombinant strain protected rabbits from lethal RHDV infection, and no histopathological changes or antigenic staining was found in the vaccine and rSWPV groups. These results suggest that rSWPV expressing RHDV VP60 could be an efficient candidate vaccine against RHDV in rabbits.

Evaluation of Ultraviolet Type C Radiation in Inactivating Relevant Veterinary Viruses on Experimentally Contaminated Surfaces.

Many swine farms employ UVC treatment in employees’ personal belongings and small tools entering farms as part of the biosecurity protocol to decrease the risk of pathogen introduction into the operation. However, the UVC efficacy in some veterinary viruses is not fully evaluated. This study evaluated the efficacy of ultraviolet type C (UVC) radiation in inactivating seven relevant veterinary viruses: Swine Poxvirus (SwPV), Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), Porcine Epidemic Diarrhea Virus (PEDV), Swine Influenza Virus (SIV), Bovine Viral Diarrhea Virus (BVDV), Porcine Parvovirus (PPV), and Senecavirus A (SVA). The experimentally contaminated materials included polystyrene and filter paper. The samples were exposed to UVC for 5 min (total dose of 360 mJ/cm2). The UVC treatment caused a decrease over 4 log10 in SwPV titer on the polystyrene surface, whereas it consistently reduced about 5 log10 in PPV and SVA samples. No viable virus was recovered from PRRSV, PEDV, SIV, and BVDV samples. In filter paper, conversely, the efficacy was reduced. This study provides essential information on the inactivation effectiveness of a specific dose of UVC on important veterinary viruses, further supporting the rational application and strategic guidance for UVC radiation use to disinfect materials.

Development of Indirect and Sandwich ELISA for Sero-surveillance and Detection of Swinepox Virus

Background: Swinepox is an economically important, classical pox disease of piglets. The present study was undertaken with a view to develop rapid serological tests to diagnose the disease. Methods: During the study period, 25 suspected swinepox outbreaks in Assam were confirmed by polymerase chain reaction with sequencing and phylogenetic analysis, further the outbreaks were confirmed by transmission electron microscopy (TEM) for identification of swinepox positive samples. The positive samples were used to isolate the virus in PK-15 cell line and develop indirect and sandwich ELISA. Result: The cell culture-based indirect ELISA was developed that demonstrated an accuracy of 88.8% compare to VNT and 100% sensitivity with 66.67% specificity, could identify 61.71% seroprevalence of swinepox in random pig serum samples. A sandwich ELISA was also developed with polyclonal sera raised in rabbits as coating antibody and swinepox positive pig serum as tracing antibody. The sandwich ELISA detected 77.78% positive cases compared to PCR. Swinepox is an emerging disease in North-eastern region with high sero-positivity observed during random sampling. This is the first report of using immune sorbent assays to detect swinepox.

Virus viability in spiked swine bone marrow tissue during above-ground burial method and under in vitro conditions.

The emergence of high consequence animal diseases usually requires managing significant mortality. A desirable aspect of any carcass management method is the ability to contain and inactivate the target pathogen. The above-ground burial (AGB) technique was recently developed and proposed as an alternative carcass management method. Here, we investigate the tenacity of swinepox virus (SwPV), as a surrogate model for African swine fever virus (ASFV) in swine carcasses during the AGB process. For this, SwPV was inoculated intrafemorally in 90 adult swine carcasses, which were subsequently disposed under AGB conditions. Bone marrow samples were recovered periodically throughout 12 months and virus viability was assessed by virus isolation (VI), whereas the presence of SwPV DNA was evaluated by quantitative polymerase chain reaction (qPCR). Additionally, an in vitro study assessed the inactivation rate of SwPV, Senecavirus A (SVA), and bovine viral diarrhoea virus (BVDV). Viral suspensions were mixed with bone marrow material and maintained at 21-23°C for 30 days. Virus viability was assessed by VI and viral titration. In the field study, SwPV remained viable only in 11 (55%) bone marrow samples collected on day 7; only viral DNA (and not infectivity) was detected afterwards. SwPV inactivation was estimated to have occurred by day 11. The in vitro testing revealed a variable tenacity of the studied viruses. The viability period was estimated in 28, 80, and 118 days, respectively, for BVDV, SwPV, and SVA. Overall, these findings indicate that the AGB technique was effective in quickly inactivating SwPV. Additionally, the SwPV inactivation rate is comparable to ASFV under field studies and poses a potential model for preliminary ASFV inactivation studies with reduced biosecurity requirements. Moreover, this study contributes to understanding the inactivation kinetics of viruses under specific conditions, which is critical when designing and applying countermeasures in case of biosecurity breaches in sites managing animal mortality.

Prolonged Viability of Senecavirus A in Exposed House Flies (Musca domestica).

House flies (Musca domestica) are often present in swine farms worldwide. These flies utilize animal secretions and waste as a food source. House flies may harbor and transport microbes and pathogens acting as mechanical vectors for diseases. Senecavirus A (SVA) infection in pigs occurs via oronasal route, and animals shed high virus titers to the environment. Additionally, SVA possesses increased environmental resistance. Due to these reasons, we investigated the tenacity of SVA in house flies. Five groups of flies, each composed of ten females and ten males, were exposed to SVA, titer of 109.3 tissue culture infectious dose (TCID50/mL). Groups of male and female flies were collected at 0, 6, 12, 24, and 48 h post-exposure. For comparison purposes, groups of flies were exposed to Swinepox virus (SwPV). Infectious SVA was identified in all tested groups. Successful isolation of SVA demonstrated the titers varied between 106.8 and 102.8 TCID50/mL in female groups and varied from 105.85 to 103.8 TCID50/mL in male groups. In contrast, infectious SwPV was only detected in the female group at 6 h. The significant SVA infectious titer for prolonged periods of time, up to 48 h, indicates a potential role of flies in SVA transmission.

Pathology and Occurrence of Swine Pox in an Organized Swine Farm-Bareilly, Uttar Pradesh

A swine pox outbreak occurred in April 2017 at Bareilly, Uttar Pradesh based organized swine production farm with roughly 200 animals. Twelve growing crossbred (Large White Yorkshire and local) animals were found to have skin lesions, which varied in size and were found on the face, ears, periorbital region, legs, ventral abdomen, inguinal region, dorsal and lateral sides, etc. The lesions ranged from papules and pustules that turned into crusty lesions that looked like brownish scabs. Microscopically, infected cells showed ballooning degeneration of epidermal and follicular epithelial cells, mild epidermal hyperplasia, nuclear vacuolation, and margination of chromatin. Multiple typical eosinophilic intracytoplasmic inclusion bodies were also seen in the epidermal cells, and inflammatory cells were infiltrating the dermis.

Swinepox Virus Strains Isolated from Domestic Pigs and Wild Boar in Germany Display Altered Coding Capacity in the Terminal Genome Region Encoding for Species-Specific Genes.

Swinepox virus (SWPV) is a globally distributed swine pathogen that causes sporadic cases of an acute poxvirus infection in domesticated pigs, characterized by the development of a pathognomonic proliferative dermatitis and secondary ulcerations. More severe disease with higher levels of morbidity and mortality is observed in congenitally SWPV-infected neonatal piglets. In this study, we investigated the evolutionary origins of SWPV strains isolated from domestic pigs and wild boar. Analysis of whole genome sequences of SWPV showed that at least two different virus strains are currently circulating in Germany. These were more closely related to a previously characterized North American SWPV strain than to a more recent Indian SWPV strain and showed a variation in the SWPV-specific genome region. A single nucleotide deletion in the wild boar (wb) SWPV strain leads to the fusion of the SPV019 and SPV020 open reading frames (ORFs) and encodes a new hypothetical 113 aa protein (SPVwb020-019). In addition, the domestic pig (dp) SWPV genome contained a novel ORF downstream of SPVdp020, which encodes a new hypothetical 71aa protein (SPVdp020a). In summary, we show that SWPV strains with altered coding capacity in the SWPV specific genome region are circulating in domestic pig and wild boar populations in Germany.

First complete genome characterization of swinepox virus directly from a clinical sample indicates divergence of a Eurasian-lineage virus.

In this study, we report the complete genome sequence of swinepox virus from a clinical sample from a naturally occurring infection in India. The sequencing was done on a Nanopore MinION sequencer from Oxford Nanopore Technologies. Two new annotations were added to the genome. Three of the genes were found to have frameshifts, which might be of importance in relation to infection. When compared to the only other reported whole genome sequence of swinepox virus, which was obtained from an isolate from America in 1999, our sequence is only 98.19% identical at the nucleotide level. The average amino acid sequence identity of the viral proteins, based on the common 149 annotations, is also 98.19%, demonstrating that these viruses are distinctly divergent. Owing to the fact that swinepox virus infects only swine, it could not have entered America until the introduction of swine in the 16th century from Europe. The swinepox viruses in both continents have continued to evolve independently. The sequence divergence identified here indicates a Eurasian-lineage virus that is geographically distinct from the American-lineage swinepox virus.

Poxvirus encoded eIF2α homolog, K3 family proteins, is a key determinant of poxvirus host species specificity

Protein kinase R plays a key role in innate antiviral immune responses of vertebrate animals. Most mammalian poxviruses encode two PKR antagonists, E3 (dsRNA binding) and K3 (eIF2α homolog) proteins. In this study, the role of K3 family proteins from poxviruses with distinct host tropisms in determining the virus host range was examined in a vaccinia E3L deletion mutant virus. It was found that K3 orthologs from the species-specific poxviruses (taterapox virus, sheeppox virus, myxoma virus, swinepox virus and yaba monkey tumor virus) restored the virus replication competency in cells derived from their natural hosts or related animal species. Further, it was found that the residues located in the helix insert region of the protein, K45 of vaccinia K3 and Y47 of the sheep poxvirus ortholog 011, are critical for the virus host species specificity. These observations demonstrate that poxvirus K3 proteins are major determinants of the virus host specificity.

Изучение культуральных и вирулентных свойств вируса оспы свиней, выделенного в Российской Федерации

Изучение культуральных и вирулентных свойств вируса оспы свиней, выделенного в Российской Федерации

Validation of a real-time PCR assay for detection of swinepox virus.

Swine are the only known hosts of swinepox virus (SWPV), the sole member of the genus Suipoxvirus, family Poxviridae. Rapid diagnosis is recommended for appropriate interventions because of the high morbidity associated with this virus. This study describes a real-time quantitative PCR (qPCR) assay for rapid detection and quantification of SWPV. The detection limit, repeatability, reproducibility, and specificity of this assay were determined. The efficiency was 96%, and the R2 value was 0.996. The detection limit was 1 fg or 10-0.5 TCID50/50 μL. Tests showed that the greatest source of error in the SWPV qPCR assay was variation between analysts rather than different qPCR kits or equipment. All nucleic acids from other viruses or samples collected from swine were negative in the specificity test. qPCR for SWPV is a new method with tested variables that allows main sources of error in laboratory diagnosis and viral quantification to be identified.

High diversity and potential translocation of DNA viruses in ballast water

Ballast water is a common vector for the transport of invasive species to new marine and aquatic environments. We used a metagenomics approach to examine the composition and diversity of viral communities in ballast water from ships originating in Mexico, Saudi Arabia, New York, and Panama, and in water from the port of their destination in Busan, Korea. Myoviridae was the most abundant virus family in ballast water, followed Podoviridae and Siphoviridae. We also identified viruses that infect invertebrates, amoebas, and algae in ballast water and in the Busan port water. Interestingly, there were several viruses that infect humans or other animals (Swinepox virus, Raccoonpox virus, Suid herpesvirus, and Human endogenous retrovirus) in the samples from New York and Panama. In addition, there were giant viruses in all the ballast water samples, especially, identified Megavirus chilensis in New York and Panama, and Pandoravirus salinus in Mexico and Saudi Arabia. These results provide detailed descriptions of the characteristics of the viruses present in ballast water, document significant viral diversity, and indicate the potential translocation of viruses via ballast water.