First virological and pathological study of Göttingen Minipigs with Dippity Pig Syndrome (DPS)

Abstract

Dippity Pig Syndrome (DPS) is a well-known but rare complex of clinical signs affecting minipigs, which has not been thoroughly investigated yet. Clinically affected animals show acute appearance of red, exudating lesions across the spine. The lesions are painful, evidenced by arching of the back (dipping), and the onset of clinical signs is generally sudden. In order to understand the pathogenesis, histological and virological investigations were performed in affected and unaffected Göttingen Minipigs (GöMPs). The following DNA viruses were screened for using PCR-based methods: Porcine cytomegalovirus (PCMV), which is a porcine roseolovirus (PCMV/PRV), porcine lymphotropic herpesviruses (PLHV-1, PLHV-2, PLHV-3), porcine circoviruses (PCV1, PCV2, PCV3, PCV4), porcine parvovirus 1 (PPV1), and Torque Teno sus viruses (TTSuV1, TTSuV2). Screening was also performed for integrated porcine endogenous retroviruses (PERV-A, PERV-B, PERV-C) and recombinant PERV-A/C and their expression as well as for the RNA viruses hepatitis E virus (HEV) and SARS-CoV-2. Eight clinically affected and one unaffected GöMPs were analyzed. Additional unaffected minipigs had been analyzed in the past. The analyzed GöMPs contained PERV-A and PERV-B integrated in the genome, which are present in all pigs and PERV-C, which is present in most, but not all pigs. In one affected GöMPs recombinant PERV-A/C was detected in blood. In this animal a very high expression of PERV mRNA was observed. PCMV/PRV was found in three affected animals, PCV1 was found in three animals with DPS and in the unaffected minipig, and PCV3 was detected in two animals with DPS and in the unaffected minipig. Most importantly, in one animal only PLHV-3 was detected. It was found in the affected and unaffected skin, and in other organs. Unfortunately, PLHV-3 could not be studied in all other affected minipigs. None of the other viruses were detected and using electron microscopy, no virus particles were found in the affected skin. No porcine virus RNA with exception of PERV and astrovirus RNA were detected in the affected skin by next generation sequencing. This data identified some virus infections in GöMPs with DPS and assign a special role to PLHV-3. Since PCMV/PRV, PCV1, PCV3 and PLHV-3 were also found in unaffected animals, a multifactorial cause of DPS is suggested. However, elimination of the viruses from GöMPs may prevent DPS.

Screening for Viruses in Indigenous Greek Black Pigs

“…Despite the high prevalence of these viruses, until now, no association between PLHVs and any pig diseases had been described [ 37 ]. However, we recently described the finding of PLHV-3 in pigs with dippity pig syndrome (DPS) [ 16 ] and in Greek pigs with erythema multiforme [ 38 ]. Whether porcine lymphotropic herpesviruses, especially PLHV-3, pose a risk for xenotransplantation is unclear.…”

“…PLHV was also not transmitted to baboons through the hearts of all eight genetically modified pigs used for orthotopic pig heart transplantation which were all positive for PLHV-3 [ 10 ]. As mentioned, PLHV-3 was also found in pigs suffering from DPS [ 16 ] and from erythema multiforme [ 38 ]. However, it remains unclear whether the virus is involved in the corresponding pathogenesis.…”

“…Real-time PCRs were performed to detect PCMV/PRV, PLHV-1, PLHV-2, PLHV-3, PCV2, PCV3, PCV4 and PPV1 as described previously using specific primers and probes ( Table 1 ) [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. All protocols were performed using the SensiFAST Probe No-ROX kit (Meridian Bioscience, Cincinnati, OH, USA) in a reaction volume of 16 µL plus 4 µL (100 ng) of DNA template.…”

“…All real-time PCRs were carried out as duplex PCRs that simultaneously indicate the gene of interest and porcine glyceraldehyde-3-phosphate-dehydrogenase (pGAPDH) as internal control for each sample. Real-time PCR reactions were carried out with a qTOWER3 G qPCR cycler (Analytik Jena, Jena, Germany) and the real-time PCR conditions as previously described [ 16 ].…”

Emergence of novel circoviruses in humans and pigs and their possible importance for xenotransplantation and blood transfusions

“…PCV3 can be found in most pigs on a global basis including wild boars and domestic pigs with or without clinical signs and are often associated with various other coinfections 38 . Interestingly, it has also been associated with unusual syndromes including erythema multiform in a Greek pig 39 and dippity pig syndrome in Göttingen minipigs 40 . It should be mentioned that PCV3 can be found in invertebrates, in ticks and mosquitoes 41,42 which could indicate that these species may serve as a potential transmission vector in the life‐cycle of PCV3.…”