A novel RNA-based in situ hybridization to detect Seneca Valley virus in neonatal piglets and sows affected with vesicular disease

Experimental Seneca Valley virus infection in sows and their offspring

Neonatal mortality has been increasingly reported on swine breeding farms experiencing swine idiopathic vesicular disease (SIVD) outbreaks, which can be accompanied by lethargy, diarrhea, and neurologic signs in neonates. Seneca Valley Virus (SVV), or Senecavirus A, has been detected in clinical samples taken from pigs with SIVD. Experimental SVV inoculation has caused vesicular disease in pigs, particularly during the stages from weaning to finishing. However, it remains crucial to investigate whether SVV directly contributes to the increase in neonatal mortality rates. The following study was conducted to chronicle the pathogenesis of SVV infection in sows and their offspring. Ten sows were intranasally inoculated with 4.75 × 107 plaque-forming units of the virus per sow either late in gestation (n = 5) or within fourteen days of farrowing (n = 5). Each sow replicated SVV following intranasal inoculation, but only one out of ten sows developed a vesicular lesion on the snout. Evidence of transplacental infection was observed in two litters, and an additional two litters became infected following parturition out of five litters from sows inoculated in late gestation. No clinical signs were observed in the infected neonates. Likewise, no clinical signs were observed in the other five litters inoculated after farrowing, although each piglet did replicate the challenge virus. In this study, the experimental challenge of SVV did not result in neonatal mortality in contrast to observations in the field; however, it has shed light on the pathogenesis of the virus, the transmission of SVV between sows and their offspring, and host immune response that can help shape control measures in the field.

First assessment of weeks-to-negative processing fluids in breeding herds after a Senecavirus A outbreak

Senecavirus A (SVA) causes vesicular disease in swine and has been responsible for a rampant increase in the yearly number of foreign animal disease investigations conducted in the United States. Diagnostic investigations for SVA are typically performed by sampling animals individually, which is labor-intensive and stressful. Developing an alternative aggregate sampling method would facilitate the detection of this virus at the population level. In a preliminary study, SVA was detected in processing fluids (PF) collected in a breeding herd before and after outbreak detection. The objective of this study was to estimate the average number of weeks PF remain SVA-positive after an SVA outbreak. Ten farrow-to-wean breeding herds volunteered to participate in this studyby longitudinally collecting PF samples after an SVA outbreak was detected and submitting samples for RT-rtPCR testing. The PF samples from the 10 farms were SVA-positive for an average of 11.8 weeks after the outbreak. Here, we show that testing of PF may be a cost-effective method to detect SVA and help halt its spread in SVA-endemic regions.

Prevalence of Senecavirus A in pigs from 2014 to 2020: a global systematic review and meta-analysis

BACKGROUND

Senecavirus A (SVA), a member of the family Picornaviridae, is newly discovered, which causes vesicular lesions, lameness in swine, and even death in neonatal piglets. SVA has rapidly spread worldwide in recent years, especially in Asia.

OBJECTIVES

We conducted a global meta-analysis and systematic review to determine the status of SVA infection in pigs.

METHODS

Through PubMed, VIP Chinese Journals Database, China National Knowledge Infrastructure, and Wanfang Data search data from 2014 to July 26, 2020, a total of 34 articles were included in this analysis based on our inclusion criteria. We estimated the pooled prevalence of SVA in pigs by the random effects model. A risk of bias assessment of the studies and subgroup analysis to explain heterogeneity was undertaken.

RESULTS

We estimated the SVA prevalence to be 15.90% (1,564/9,839; 95% confidence interval [CI], 44.75-65.89) globally. The prevalence decreased to 11.06% (945/8,542; 95% CI, 28.25-50.64) after 2016. The highest SVA prevalence with the VP1-based RT-PCR and immunohistochemistry assay was 58.52% (594/1,015; 95% CI, 59.90-83.96) and 85.54% (71/83; 95% CI, 76.68-100.00), respectively. Besides, the SVA prevalence in piglet herds was the highest at 71.69% (119/166; 95% CI, 68.61-98.43) (p < 0.05). Moreover, our analysis confirmed that the subgroups, including country, sampling year, sampling position, detected gene, detection method, season, age, and climate, could be the heterogeneous factors associated with SVA prevalence.

CONCLUSIONS

The results indicated that SVA widely exists in various countries currently. Therefore, more prevention and control policies should be proposed to enhance the management of pig farms and improve breeding conditions and the environment to reduce the spread of SVA.

A Review on Pathological and Diagnostic Aspects of Emerging Viruses—Senecavirus A, Torque teno sus virus and Linda Virus—In Swine

Simple Summary

Worldwide demand for food is expected to increase due to population growth and swine accounts for more than one-third of meat produced worldwide. Several factors affect the success of livestock production systems, including animal disease control. Despite the importance of infectious diseases to animal health and the productivity of the global swine industry, pathogens of swine, in particular emerging viruses, such as Senecavirus A, Torque teno sus virus, and Linda virus, have gained limited interest. We performed a systematic analysis of the literature, with a focus on the main macroscopical and histological findings related to those viruses to fill the gap and highpoint these potentially hazardous pathogens.

Abstract

Swine production represents a significant component in agricultural economies as it occupies over 30% of global meat demand. Infectious diseases could constrain the swine health and productivity of the global swine industry. In particular, emerging swine viral diseases are omnipresent in swine populations, but the limited knowledge of the pathogenesis and the scarce information related to associated lesions restrict the development of data-based control strategies aimed to reduce the potentially great impact on the swine industry. In this paper, we reviewed and summarized the main pathological findings related to emerging viruses, such as Senecavirus A, Torque teno sus virus, and Linda virus, suggesting a call for further multidisciplinary studies aimed to fill this lack of knowledge and better clarify the potential role of those viral diseases in swine pathology.

Persistence and shedding of senecavirus A in naturally infected boars

Senecavirus A (SVA) infection in pigs causes vesicular disease and results in a short viremia and transient shedding of the virus, mainly in oral fluids and feces. Here we describe the consistent prolonged shedding of SVA in the semen of 2 boars, and persistence of SVA within the tonsils and testes of 3 adult boars. Two SVA-infected boars that were identified on a Minnesota sow farm in 2017 shed SVA RNA in semen for >3 mo after an outbreak of vesicular disease had occurred on the farm. SVA was isolated from 1 semen sample collected 9 d after clinical disease began on the farm. The third SVA-infected boar was identified on an Indiana sow farm in 2020. All boars had SVA RNA detected in the testes and tonsils by RT-rtPCR, with lower Ct values obtained for the testes than from the tonsils. All boars had multifocal lymphocytic orchitis with segmental degeneration and atrophy of the germinal epithelium within the seminiferous tubules. One boar also had areas of seminiferous tubule collapse and interstitial fibrosis within the testes. In all boars, in situ hybridization demonstrated the presence of SVA mRNA within cells located basally in the seminiferous tubules of the testes, and within the basal surface epithelial cells, crypt epithelial cells, and subepithelial and parafollicular lymphocytes and histiocytes of the tonsil.

Development of a VP2-based real-time fluorescent reverse transcription recombinase-aided amplification assay to rapidly detect Senecavirus A

Senecavirus A (SVA), a newly emergent picornavirus correlated with sudden neonatal mortality and vesicular lesions in pigs, has had a considerable impact on the global pig farming industry. Timely and dependable detection of SVA is helpful in preventing the further spread of this pathogenic virus. In the current study, a real-time fluorescent reverse transcription recombinase-aided amplification (rRT-RAA) assay, which targets the most conserved region within the VP2 gene of SVA, was developed and evaluated for SVA detection. The detection limit for this assay was tested to be 1.185 50% tissue culture infective dose (TCID₅₀ ) of SVA RNA per reaction at a 95% confidence interval, which is comparable to that of a previously published rRT-PCR assay for SVA. The testing results of the rRT-RAA assay were very reproducible and repeatable, with inter- and intra-assay coefficient of variation values less than 7.0%. In addition, the established rRT-RAA assay displayed excellent specificity for SVA detection without cross-reaction with other clinically important swine pathogenic viruses. The diagnostic performance of rRT-RAA was evaluated using 189 clinical swine samples, which were detected in parallel using the reference rRT-PCR assay. The results showed that 146 and 151 samples tested positive for SVA by rRT-RAA and rRT-PCR, respectively. The overall agreement between both assays was 97.4% (184/189) with a kappa value of 0.927 (p < .001). Further linear regression analysis demonstrated that the detection results between the two assays were significantly correlated (R² = 0.9192, p < .0001). Taken together, our newly established rRT-RAA assay is a powerful and time-saving diagnostic tool for SVA detection in clinical samples. This article is protected by copyright. All rights reserved.

In Situ Hybridization of PRRSV-1 Combined with Digital Image Analysis in Lung Tissues of Pigs Challenged with PRRSV-1

Betaarterivirus suid 1 and 2 are the causative agents of porcine reproductive and respiratory syndrome (PRRS), which is one of the most significant diseases of the swine industry, causing significant economic losses in the main pig producing countries. Here, we report the development of a novel, RNA-based in situ hybridization technique (RNAscope) to detect PRRS virus (PRRSV) RNA in lung tissues of experimentally infected animals. The technique was applied to lung tissues of 20 piglets, which had been inoculated with a wild-type, highly pathogenic PRRSV-1 strain. To determine the RNAscope's applicability as a semi-quantitative method, we analysed the association between the proportion of the virus-infected cells measured with an image analysis software (QuPath) and the outcome of the real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) tests performed in parallel. The results of the quantitative approach of these two molecular biological methods show significant association (pseudo R2 = 0.3894, p = 0.004). This is the first time RNAscope assay has been implemented for the detection of PRRSV-1 in experimental animals.

Histological Lesions and Replication Sites of PCV3 in Naturally Infected Pigs

Simple Summary

Diagnosing porcine circovirus type 3 (PCV3) is a challenge in pig production. Although the virus has been recently isolated, the patterns of PCV3-associated histological lesions are still to be elucidated. The present study describes the association of PCV3 mRNA by in situ hybridization within histological lesions and PCV3 DNA detected by real-time PCR in naturally infected pigs. The main histologic lesions associated with PCV3 mRNA detection were lymphoplasmacytic myocarditis and lymphoplasmacytic interstitial pneumonia, in heart and lung, respectively. Our findings offer robust guidance of microscopic lesions associated with PCV3, which may have a key role in PCV3 diagnosis.

Abstract

Porcine circovirus type 3 (PCV3) has been recently described as a potential cause of abortions and systemic vasculitis in pigs. Although the virus has been detected by real-time PCR in several porcine tissues from countries worldwide, PCV3-associated diseases have not been satisfactorily clarified. The objective of this study was to investigate the association between the presence of PCV3 mRNA detected by in situ hybridization (ISH) within histological lesions and PCV3 DNA detected by real-time PCR in naturally infected pigs. A total of 25 PCV3 PCR-positive cases were analyzed. Formalin-fixed tissues from these cases were evaluated for histologic lesions and for ISH-RNA positive signals for PCV3. The most frequent tissue type with histopathologic lesions was heart, 76.2%, with lymphoplasmacytic myocarditis and epicarditis as the most frequent lesions observed. Lymphoplasmacytic interstitial pneumonia was also a frequent finding, 47.6%. There were also lesions in kidney, liver, spleen and lymph nodes. PCV3-ISH-RNA positive signals were mostly observed in association with lymphoplasmacytic inflammatory infiltrate in various tissues, including arteries. Based on our results, the minimum set of specimens to be submitted for histopathology and mRNA in situ hybridization to confirm or exclude a diagnosis of PCV3 are heart, lung and lymphoid tissues (i.e., spleen and lymph nodes), especially for differential diagnosis related with PCV2-associated diseases.

N-Linked Glycosylation on Anthrax Toxin Receptor 1 Is Essential for Seneca Valley Virus Infection

Seneca Valley virus (SVV) is a picornavirus with potency in selectively infecting and lysing cancerous cells. The cellular receptor for SVV mediating the selective tropism for tumors is anthrax toxin receptor 1 (ANTXR1), a type I transmembrane protein expressed in tumors. Similar to other mammalian receptors, ANTXR1 has been shown to harbor N-linked glycosylation sites in its extracellular vWA domain. However, the exact role of ANTXR1 glycosylation on SVV attachment and cellular entry was unknown. Here we show that N-linked glycosylation in the ANTXR1 vWA domain is necessary for SVV attachment and entry. In our study, tandem mass spectrometry analysis of recombinant ANTXR1-Fc revealed the presence of complex glycans at N166, N184 in the vWA domain, and N81 in the Fc domain. Symmetry-expanded cryo-EM reconstruction of SVV-ANTXR1-Fc further validated the presence of N166 and N184 in the vWA domain. Cell blocking, co-immunoprecipitation, and plaque formation assays confirmed that deglycosylation of ANTXR1 prevents SVV attachment and subsequent entry. Overall, our results identified N-glycosylation in ANTXR1 as a necessary post-translational modification for establishing stable interactions with SVV. We anticipate our findings will aid in selecting patients for future cancer therapeutics, where screening for both ANTXR1 and its glycosylation could lead to an improved outcome from SVV therapy.

Comprehensive review on immunopathogenesis, diagnostic and epidemiology of Senecavirus A

Senecavirus A (SVA), formerly known as Seneca Valley virus, is a single-strand, positive-sense RNA virus in the family Picornaviridae. This virus has been associated with recent outbreaks of vesicular disease (SVA-VD) and epidemic transient neonatal losses (ETNL) in several swine-producing countries. The clinical manifestation of and lesion caused by SVA are indistinguishable from other vesicular diseases. Pathogenicity studies indicate that SVA could regulate the host innate immune response to facilitate virus replication and the spread of the virus to bystander cells. SVA infection can induce specific humoral and cellular responses that can be detected within the first week of infection. However, SVA seems to produce persistent infection, and the virus can be shed in oral fluids for a month and detected in tissues for approximately two months after experimental infection. SVA transmission could be horizontal or vertical in infected herds of swine, while positive animals can also remain subclinical. In addition, mice seem to act as reservoirs, and the virus can persist in feed and feed ingredients, increasing the risk of introduction into naïve farms. Besides the pathological effects in swine, SVA possesses cytolytic activity, especially in neoplastic cells. Thus, SVA has been evaluated in phase II clinical trials as a virotherapy for neuroendocrine tumors. The goal of this review is summarize the current SVA-related research in pathogenesis, immunity, epidemiology and advances in diagnosis as well as discuses current challenges with subclinical/persistent presentation.

Next-Generation Sequencing Coupled With in situ Hybridization: A Novel Diagnostic Platform to Investigate Swine Emerging Pathogens and New Variants of Endemic Viruses

Next generation sequencing (NGS) can be applied to identify and characterize the entire set of microbes within a sample. However, this platform does not provide a morphological context or specific association between the viral or bacterial sequences detected and the histological lesions. This limitation has generated uncertainty whether the sequences identified by NGS are actually contributing or not for the clinical outcome. Although in situ hybridization (ISH) and immunohistochemistry (IHC) can be used to detect pathogens in tissue samples, only ISH has the advantage of being rapidly developed in a context of an emerging disease, especially because it does not require development of specific primary antibodies against the target pathogen. Based on the sequence information provided by NGS, ISH is able to check the presence of a certain pathogen within histological lesions, by targeting its specific messenger RNA, helping to build the relationship between the pathogen and the clinical outcome. In this mini review we have compiled results of the application of NGS-ISH to the investigation of challenging diagnostic cases or emerging pathogens in pigs, that resulted in the detection of porcine circovirus type 3, porcine parvovirus type 2, Senecavirus A, and Mycoplasma hyorhinis.

Persistent Infection and Transmission of Senecavirus A from Carrier Sows to Contact Piglets

Senecavirus A (SVA) is a picornavirus that causes acute vesicular disease (VD), that is clinically indistinguishable from foot-and-mouth disease (FMD), in pigs. Notably, SVA RNA has been detected in lymphoid tissues of infected animals several weeks following resolution of the clinical disease, suggesting that the virus may persist in select host tissues. Here, we investigated the occurrence of persistent SVA infection and the contribution of stressors (transportation, immunosuppression, or parturition) to acute disease and recrudescence from persistent SVA infection. Our results show that transportation stress leads to a slight increase in disease severity following infection. During persistence, transportation, immunosuppression, and parturition stressors did not lead to overt/recrudescent clinical disease, but intermittent viremia and virus shedding were detected up to day 60 postinfection (p.i.) in all treatment groups following stress stimulation. Notably, real-time PCR and in situ hybridization (ISH) assays confirmed that the tonsil harbors SVA RNA during the persistent phase of infection. Immunofluorescence assays (IFA) specific for double-stranded RNA (dsRNA) demonstrated the presence of double-stranded viral RNA in tonsillar cells. Most importantly, infectious SVA was isolated from the tonsil of two animals on day 60 p.i., confirming the occurrence of carrier animals following SVA infection. These findings were supported by the fact that contact piglets (11/44) born to persistently infected sows were infected by SVA, demonstrating successful transmission of the virus from carrier sows to contact piglets. Results here confirm the establishment of persistent infection by SVA and demonstrate successful transmission of the virus from persistently infected animals.IMPORTANCE Persistent viral infections have significant implications for disease control strategies. Previous studies demonstrated the persistence of SVA RNA in the tonsil of experimentally or naturally infected animals long after resolution of the clinical disease. Here, we showed that SVA establishes persistent infection in SVA-infected animals, with the tonsil serving as one of the sites of virus persistence. Importantly, persistently infected carrier animals shedding SVA in oral and nasal secretions or feces can serve as sources of infection to other susceptible animals, as evidenced by successful transmission of SVA from persistently infected sows to contact piglets. These findings unveil an important aspect of SVA infection biology, suggesting that persistently infected pigs may function as reservoirs for SVA.

Rapid and sensitive detection of Senecavirus A by reverse transcription loop-mediated isothermal amplification combined with a lateral flow dipstick method

Senecavirus A (SVA) is a critical pathogen causing vesicular lesions in sows and acute death of newborn piglets, resulting in very large economic losses in the pig industry. To restrict the transmission of SVA, an establishment of an effective diagnostic method is crucial for the prevention and control of the disease. However, traditional detection methods often have many drawbacks. In this study, reverse transcription loop-mediated isothermal amplification (RT-LAMP) was combined with a lateral flow dipstick (LFD) to detect SVA. The resulting RT-LAMP-LFD assay was performed at 60°C for 50 min and then directly judged on an LFD visualization strip. This method shows high specificity and sensitivity to SVA. The detection limit of RT-LAMP was 4.56x10^-8 ng/μL RNA, approximately 11 copies/μL RNA, and it was 10 times more sensitive than RT-PCR. This detection method’s positive rate for clinical samples is comparable to that of RT-PCR. This method is time saving and highly efficient and is thus expected to be used to diagnose SVA infections in this field.

Reverse transcriptase droplet digital PCR to identify the emerging vesicular virus Senecavirus A in biological samples

Senecavirus A (SVA) belonging to the family Picornaviridae, genus Senecavirus was incidentally isolated in 2002 from the PER.C6 (transformed foetal retinoblast) cell line. However, currently, this virus is associated with vesicular disease in swine and it has been reported in countries such as the United States of America, Canada, China, Thailand and Colombia. In Brazil, the SVA was firstly reported in 2015 in outbreaks of vesicular disease in swine, clinically indistinguishable of Foot-and-mouth disease, a contagious viral disease that generates substantial economic losses. In the present work, it was standardized a diagnostic tool for SVA based on RNA reverse transcriptase droplet digital PCR (RT-ddPCR) using one-step and two-step approaches. Analytical sensitivity and specificity were done in parallel with real-time PCR, RT-qPCR (one-step and two-step) for comparison of sensitivity and specificity of both methods. In the standardization of RT-ddPCR, the double-quenched probe and the temperature gradient were crucial to reduce background and improve amplitude between positive and negative droplets. The limit of detection and analytical specificity of techniques of one-step techniques showed superior performance than two-step methods described here. Additionally, the results showed 94.2% concordance (p < 0.001) for RT-ddPCR and RT-qPCR using the one-step assay approach and biological samples from Brazilian outbreaks of Senecavirus A. However, ddRT-PCR had a better performance than RT-PCR when swine serum pools were tested. According to the results, the one-step RT-ddPCR and RT-qPCR is highlighted to be used as an auxiliary diagnostic tool for Senecavirus A and for viral RNA absolute quantification in biological samples (RT-ddPCR), being a useful tool for vesicular diseases control programs.

Senecavirus A 3C Protease Mediates Host Cell Apoptosis Late in Infection

Senecavirus A (SVA), an oncolytic picornavirus used for cancer treatment in humans, has recently emerged as a vesicular disease (VD)-causing agent in swine worldwide. Notably, SVA-induced VD is indistinguishable from foot-and-mouth disease (FMD) and other high-consequence VDs of pigs. Here we investigated the role of apoptosis on infection and replication of SVA. Given the critical role of the nuclear factor-kappa B (NF-κB) signaling pathway on modulation of cell death, we first assessed activation of NF-κB during SVA infection. Results here show that while early during infection SVA induces activation of NF-κB, as evidenced by nuclear translocation of NF-κB-p65 and NF-κB-mediated transcription, late in infection a cleaved product corresponding to the C-terminus of NF-κB-p65 is detected in infected cells, resulting in lower NF-κB transcriptional activity. Additionally, we assessed the potential role of SVA 3C protease (3Cpro) in SVA-induced host-cell apoptosis and cleavage of NF-κB-p65. Transient expression of SVA 3Cpro was associated with cleavage of NF-κB-p65 and Poly (ADP-ribose) polymerase (PARP), suggesting its involvement in virus-induced apoptosis. Most importantly, we showed that while cleavage of NF-κB-p65 is secondary to caspase activation, the proteolytic activity of SVA 3Cpro is essential for induction of apoptosis. Experiments using the pan-caspase inhibitor Z-VAD-FMK confirmed the relevance of late apoptosis for SVA infection, indicating that SVA induces apoptosis, presumably, as a mechanism to facilitate virus release and/or spread from infected cells. Together, these results suggest an important role of apoptosis for SVA infection biology.

Seroprevalence of Senecavirus A in sows and grower-finisher pigs in major swine producing-states in the United States

Senecavirus A (SVA) is a single-stranded RNA virus in the family Picornaviridae. Recently, SVA has been associated with idiopathic vesicular disease and increased neonate mortality outbreaks in the United States, Brazil, China, Colombia, and Thailand, with increasing incidence since 2014. Indirect detection by antibody detection methods, including indirect immunofluorescence assay (IFA), virus neutralization assay, and competitive or indirect enzyme-linked immunosorbent assays (ELISAs), have been reported in clinical and experimental trials. The objective of this study was to determine the seroprevalence of SVA in nonclinical affected herds in the United States. Individual samples were collected from 3654 and 2433 clinically healthy grower-finisher pigs and sows, respectively, from 219 unique commercial swine production sites. SVA seroprevalence was evaluated by SVA rVP1 ELISA and SVA IFA. The estimated seroprevalence for grower-finisher pigs and sows was 12.2% and 34.0%, respectively. The herd prevalence was 42.7% for grower-finisher farms and 75.8% for sow farms. The SVA rVP1 ELISA and SVA IFA exhibited a fair (sows) and moderate (grower-finisher) agreement at the herd level, while a fair agreement was observed at the individual level for both pig categories evaluated. The McNemar's test was significant at the individual and herd level (p <  0.05). In this study, we demonstrated the presence of SVA IgG antibodies in pigs from clinically healthy grower-finisher and sow herds. These results suggest that SVA is circulating subclinically in sow farms and grower-finisher pig farms in major swine producing-states in the United States.

In situ hybridization detection and subtyping of rotaviruses in swine samples

Rotavirus groups A, B, and C (RVA, RVB, and RVC, respectively) have been the most prevalent and pathogenic in pigs. To date, immunohistochemistry is only available for RVA because of the lack of commercial antibodies for RVB and RVC. We developed a novel in situ hybridization RNA-based chromogenic technique (ISH-RNA) to detect and subtype RVA, RVB, and RVC. We evaluated 33 samples that were reverse-transcription PCR positive for RVA, RVB, and/or RVC. ISH-RNA was able to detect as few as 10³ RV RNA copies/mL. The new ISH-RNA test can be useful for routine investigation of rotavirus enteritis in order to guide strategies for control of the infection in pigs, but a full validation study needs to be completed. Pathogenesis studies may be conducted using ISH-RNA based on the identification of replicating virus.

Development of a real time loop-mediated isothermal amplification method for detection of Senecavirus A

Senecavirus A (SVA), formerly known as Seneca Valley Virus (SVV), is one of causative agents of vesicular diseases in swine. Recently, the outbreaks associated with vesicular disease caused by SVA infection in pig herds have been reported in Brazil, USA, China, Thailand and Canada. Several molecular detection methods have been established to determine the infection of SVA, including real time reverse transcription PCR assay, nested PCR, a TaqMan-based qRT-PCR assay and RNA-based in situ hybridization method. In our study, an assay for the identification of SVA in pig herds using real time reverse transcription loop-mediated isothermal amplification (real time RT-LAMP) was developed. The limit of detection for the assay was 1 TCID₅₀/ml. One hundred and eighteen field samples from pigs were used to validate the assay for clinical application. Our result demonstrated that real time RT-LAMP assay is a cost-effective and highly specific and sensitive alternative for the rapid detection of SVA in clinical samples.

Review of Seneca Valley Virus: A Call for Increased Surveillance and Research

Seneca Valley virus (SVV) has recently caused many vesicular diseases in pigs in different regions and countries. As a newly causative agent of porcine vesicular disease, SVV has evolved and spread quickly. It causes clinical signs similar to those of foot-and-mouth disease and results in significant economic losses. An increasing number of SVV outbreaks were reported in 2016 and 2017 in Brazil, United States, and China. However, few diagnostic methods have been established and no commercial vaccine has been available until now. Therefore, more attention needs to be paid to SVV, and urgent surveillance should be performed to prevent the spread of this virus. Although recent research has shed some light on SVV, there are still many aspects of the virus and the disease that are not yet fully understood, and many questions need to be resolved. This review presents current knowledge concerning SVV infection, epidemiology, pathogenicity, immune response, and diagnostic methods. This information will aid the design and adoption of effective prevention and control strategies to counter this viral pathogen.

Histopathological, immunohistochemical, and ultrastructural evidence of spontaneous Senecavirus A-induced lesions at the choroid plexus of newborn piglets

Epidemic Transient Neonatal Losses (ETNL) is a disease of piglets caused by Senecavirus A (SVA) in which the method of dissemination and associated lesions are not well-defined. This study investigated the possible SVA-induced lesions by examining spontaneous infections in newborn piglets. Histopathology revealed ballooning degeneration of transitional epithelium, nonsuppurative meningoencephalitis, plexus choroiditis, and atrophic enteritis. RT-PCR identified SVA in all tissues evaluated and sequencing confirmed these results. Positive immunoreactivity to SVA was observed in endothelial and epithelial tissues of all organs evaluated. Semithin analysis revealed vacuolization of apical enterocytes of the small intestine, balloon degeneration and necrosis of endothelial cells of the choroid plexus (CP) and nonsuppurative choroid plexitis. Ultrathin evaluation demonstrated hydropic degeneration of apical enterocytes, degeneration and necrosis of endothelium of CP fenestrated capillaries, degeneration of ependymocytes associated with intralesional viral particles. It is proposed that SVA initially infects apical enterocytes of newborn piglets and probably enters the circulatory system with entry to the brain via the CP, by first producing an initial inflammatory reaction, with subsequent encephalitic dissemination. Consequently, SVA probably uses an enteric-neurological method of dissemination.

The Scope of Big Data in One Medicine: Unprecedented Opportunities and Challenges

Advances in high-throughput molecular biology and electronic health records (EHR), coupled with increasing computer capabilities have resulted in an increased interest in the use of big data in health care. Big data require collection and analysis of data at an unprecedented scale and represents a paradigm shift in health care, offering (1) the capacity to generate new knowledge more quickly than traditional scientific approaches; (2) unbiased collection and analysis of data; and (3) a holistic understanding of biology and pathophysiology. Big data promises more personalized and precision medicine for patients with improved accuracy and earlier diagnosis, and therapy tailored to an individual’s unique combination of genes, environmental risk, and precise disease phenotype. This promise comes from data collected from numerous sources, ranging from molecules to cells, to tissues, to individuals and populations—and the integration of these data into networks that improve understanding of heath and disease. Big data-driven science should play a role in propelling comparative medicine and “one medicine” (i.e., the shared physiology, pathophysiology, and disease risk factors across species) forward. Merging of data from EHR across institutions will give access to patient data on a scale previously unimaginable, allowing for precise phenotype definition and objective evaluation of risk factors and response to therapy. High-throughput molecular data will give insight into previously unexplored molecular pathophysiology and disease etiology. Investigation and integration of big data from a variety of sources will result in stronger parallels drawn at the molecular level between human and animal disease, allow for predictive modeling of infectious disease and identification of key areas of intervention, and facilitate step-changes in our understanding of disease that can make a substantial impact on animal and human health. However, the use of big data comes with significant challenges. Here we explore the scope of “big data,” including its opportunities, its limitations, and what is needed capitalize on big data in one medicine.

Update on Senecavirus Infection in Pigs

Senecavirus A (SVA) is a positive-sense single-stranded RNA virus that belongs to the Senecavirus genus within the Picornaviridae family. The virus has been silently circulating in pig herds of the USA since 1988. However, cases of senecavirus-associated vesicular disease were reported in Canada in 2007 and in the USA in 2012. Since late 2014 and early 2015, an increasing number of senecavirus outbreaks have been reported in pigs in different producing categories, with this virus being detected in Brazil, China, and Thailand. Considering the novel available data on senecavirus infection and disease, 2015 may be a divisor in the epidemiology of the virus. Among the aspects that reinforce this hypothesis are the geographical distribution of the virus, the affected pig-producing categories, clinical signs associated with the infection, and disease severity. This review presents the current knowledge regarding the senecavirus infection and disease, especially in the last two years. Senecavirus epidemiology, pathogenic potential, host immunological response, diagnosis, and prophylaxis and control measures are addressed. Perspectives are focused on the need for complete evolutionary, epidemiological and pathogenic data and the capability for an immediate diagnosis of senecavirus infection. The health risks inherent in the swine industry cannot be neglected.