| 1. |
- Stenberg, Hedvig, et al.
(author)
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A review of congenital tremor type A-II in piglets
- 2020
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In: Animal Health Research Reviews. - 1466-2523 .- 1475-2654. ; 21, s. 84-88
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Research review (peer-reviewed)abstract
- Congenital tremor (CT) is a neurological disease that affects new-born piglets. It was described in 1922 and six different forms, designated type AI-V and type B, are described based on the causative agents, as well as specific histological findings in the central nervous system (CNS). The various forms present with identical clinical signs consisting of mild to severe tremor of the head and body, sometimes complicated with ataxia. By definition, all A-forms have hypomyelination of the CNS, whereas there are no histopathological lesions with the B-form. The cause of the A-II form was long unknown, however, at present several different viruses have been proposed as the causative agent: porcine circovirus-II (PCV-II), astrovirus, PCV-like virus P1, and atypical porcine pestivirus (APPV). Currently, APPV is the only virus that has been proven to fulfill Mokili's Metagenomic Koch's Postulates. Following infection of the pregnant sow, the virus passes the placental barrier and infects the fetus. Interestingly, no clinical signs of disease have been associated with APPV in adult pigs. Furthermore, other viruses cannot be ruled out as additional potential causes of CT. Given the increased interest and research in CT type A-II, the aim of this review is to summarize current knowledge.
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| 2. |
- Stenberg, Hedvig, et al.
(author)
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Atypical porcine pestivirus-A widespread virus in the Swedish wild boar population
- 2022
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In: Transboundary and Emerging Diseases. - : Hindawi Limited. - 1865-1674 .- 1865-1682. ; 69, s. 2349-2360
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Journal article (peer-reviewed)abstract
- The recently identified causative agent of congenital tremor in domestic piglets, atypical porcine pestivirus (APPV), was detected in serum from Swedish wild boar. A previous study from Sweden described APPV in domestic piglets suffering from congenital tremor, but the APPV situation in the wild boar population was unknown. In this study, 595 serum samples from wild boar originating from 13 counties in the south and central parts of Sweden, collected between 2000 and 2018, were analysed for the presence of the APPV-genome and for antibodies against the APPV-glycoprotein E-rns. The results revealed that APPV is highly abundant in the Swedish wild boar population; 12% (73/595) were APPV-genome positive in serum and 72% (433/595) of the tested wild boars displayed APPV-specific antibodies. The present study also shows that APPV has been present in the Swedish wild boar population since at least the year 2000. The viral sequences obtained from the wild boars were highly similar to those obtained from Swedish domestic pigs positive for APPV and suffering from congenital tremor, suggesting a viral exchange between wild boars and domestic pigs. The high proportion of viraemic and seropositive wild boar is indicative of wild boar being an important reservoir for APPV.
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| 3. |
- Stenberg, Hedvig, et al.
(author)
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Congenital tremor and splay leg in piglets - insights into the virome, local cytokine response, and histology
- 2022
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In: BMC Veterinary Research. - : Springer Science and Business Media LLC. - 1746-6148. ; 18
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Journal article (peer-reviewed)abstract
- Background: Atypical porcine pestivirus (APPV) is a neurotropic virus associated with congenital tremor type A-II. A few experimental studies also indicate an association between APPV and splay leg. The overarching aim of the present study was to provide insights into the virome, local cytokine response, and histology of the CNS in piglets with signs of congenital tremor or splay leg.Results: Characterization of the cytokine profile and virome of the brain in piglets with signs of congenital tremor revealed an APPV-associated upregulation of Stimulator of interferon genes (STING). The upregulation of STING was associated with an increased expression of the gene encoding IFN-alpha but no differential expression was recorded for the genes encoding CXCL8, IFN-beta, IFN-gamma, IL-1 beta, IL-6, or IL-10. No viral agents or cytokine upregulation could be detected in the spinal cord of piglets with signs of splay leg or in the brain of piglets without an APPV-infection. The histopathological examination showed no lesions in the CNS that could be attributed to the APPV-infection, as no difference between sick and healthy piglets could be seen.Conclusion: The results from this study provide evidence of an APPV-induced antiviral cytokine response but found no lesions related to the infection nor any support for a common causative agent.
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| 4. |
- Stenberg, Hedvig
(author)
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Congenital tremor and splay leg in Swedish piglets : a study of the viral causes and routes of transmission
- 2023
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Doctoral thesis (other academic/artistic)abstract
- Congenital tremor (CT) and splay leg (SL) are diseases regularly seen in new-born piglets in Sweden. They are diagnosed based on the clinical picture, which in CT are tremor and sometimes ataxia, and in SL, a lack of adduction of the hind legs. The cause of the clinical signs is unknown, but impaired nerve function due to myelin damage is a theory. However, the syndromes are transient, and piglets that can nurse often recover within some months. For decades, there has been speculation about the causes of these diseases. Infection in utero with certain viruses, hereditary factors, and drug treatment of pregnant sows may induce the syndromes in the offspring. In Sweden, one type of CT has been described: CT type A-II, a variant that for a long time was suspected to be caused by an unknown virus. Then, in 2015, a new virus named atypical porcine pestivirus (APPV) was discovered, and in 2016, APPV was associated with CT type A-II. There were also indications of an association between APPV and SL. This thesis aimed to investigate viral causes of CT type A-II and SL in Swedish piglets. APPV was detected in brain tissue from piglets with signs of CT type A-II, both in new and historical material. The virus could also be detected in commercial boar semen from a Swedish boar stud and in serum samples from Swedish wild boars. However, the virus was not found in piglets with splay leg or in healthy piglets, and high-throughput sequencing of the material did not reveal any other relevant viruses. Consequently, it seems unlikely that APPV, or any other virus, would be the primary cause of SL in Sweden.
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| 5. |
- Stenberg, Hedvig, et al.
(author)
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Detection of atypical porcine pestivirus in Swedish piglets with congenital tremor type A-II
- 2020
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In: BMC Veterinary Research. - : Springer Science and Business Media LLC. - 1746-6148. ; 16
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Journal article (peer-reviewed)abstract
- BackgroundCongenital tremor (CT) type A-II is a neurological disorder characterized by tremor of the head and body of newborn piglets. The suggested causative agent of the disease is the recently found atypical porcine pestivirus (APPV). The virus has been detected in piglets suffering from congenital tremor in central Europe, South and North America and in China but no studies has so far been performed in the Nordic countries. The overarching goal of this study was to investigate if APPV is present in the brain tissue of Swedish piglets suffering from congenital tremor.From June 2017 - June 2018, 15 piglets from four Swedish farms with ongoing outbreaks of congenital tremor and 13 piglets with splay leg originating from four different farms, were investigated for presence of APPV RNA in brain tissue. Matched healthy control piglets (n=8) were also investigated. Two APPV-specific RT-qPCR methods targeting the NS3 and NS5B region, respectively, were used. A retrospective study was performed on material from Swedish piglets with congenital tremor sampled in 2004 (n=11) and 2011/2012 (n=3) using the described APPV-specific RT-qPCR methods. The total number of piglets with signs of CT in this study was 29.ResultsAtypical porcine pestivirus-RNA was detected in 93% (27/29) of the piglets suffering from congenital tremor. All piglets with congenital tremor from 2004 (n=11) and 2012 (n=3) were PCR-positive with respect to APPV, whereas, all of the healthy controls (n=11) were negative. The piglets with congenital tremor sampled 2017-2018 had an odds ratio of 91.8 (95% CI 3.9128 to 2153.7842, z=2.807, P=0.0050) to test positive for APPV by qRT-PCR compared to the healthy piglets (Fishers exact test p<0.0001). These findings make it interesting to continue investigating APPV in the Swedish pig-population.ConclusionThis is the first description of atypical porcine pestivirus in piglets suffering from congenital tremor type A-II in Sweden and the Nordic countries. The virus has been present in the Swedish pig population since at least 2004.
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| 6. |
- Stenberg, Hedvig, et al.
(author)
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Screening for atypical porcine pestivirus in Swedish boar semen used for artificial insemination and a characterisation of the seminal RNA microbiome including the virome
- 2023
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In: BMC Veterinary Research. - 1746-6148. ; 19
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Journal article (peer-reviewed)abstract
- BackgroundThis study aimed to characterise the RNA microbiome, including the virome of extended semen from Swedish breeding boars, with particular focus on Atypical porcine pestivirus (APPV). This neurotropic virus, associated with congenital tremor type A-II in piglets, was recently demonstrated to induce the disease through insemination with semen from infected boars.ResultsFrom 124 Artificial Insemination (AI) doses from Swedish breeding boars, APPV was detected in one dose in addition to a sparse seminal RNA virome, characterised by retroviruses, phages, and some fecal-associated contaminants. The detected seminal microbiome was large and characterized by Gram-negative bacteria from the phylum Proteobacteria, mainly consisting of apathogenic or opportunistic bacteria. The proportion of bacteria with a pathogenic potential was low, and no antimicrobial resistance genes (ARGs) were detected in the datasets.ConclusionOverall, the results indicate a good health status among Swedish breeding boars. The detection of APPV in semen raises the question of whether routine screening for APPV in breeding boars should be instigated.
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