Similar frequency of Porcine circovirus 3 (PCV‐3) detection in serum samples of pigs affected by digestive or respiratory disorders and age‐matched clinically healthy pigs

Abstract

Porcine circovirus 3 (PCV‐3) has been identified in pigs affected by different disease conditions, although its pathogenicity remains unclear. The objective of the present study was to assess the frequency of PCV‐3 infection in serum samples from animals suffering from post‐weaning respiratory or digestive disorders as well as in healthy animals. A total of 315 swine serum samples were analysed for PCV‐3 DNA detection by conventional PCR; positive samples were further assayed with a quantitative PCR and partially sequenced. Sera were obtained from 4 week‐ to 4 month‐old pigs clinically diagnosed with respiratory (n = 129) or digestive (n = 126) disorders. Serum samples of age‐matched healthy animals (n = 60) served as negative control. Pigs with clinical respiratory signs had a wide variety of pulmonary lesions including suppurative bronchopneumonia, interstitial pneumonia, fibrinous‐necrotizing pneumonia and/or pleuritis. Animals with enteric signs displayed histopathological findings like villus atrophy and fusion, catarrhal enteritis and/or catarrhal colitis. Overall, PCV‐3 DNA was detected in 19 out of 315 analysed samples (6.0%). Among the diseased animals, PCV‐3 was found in 6.2% (8 out of 129) and 5.6% (7 out of 126) of pigs with respiratory and digestive disorders, respectively. The frequency of PCV‐3 PCR positive samples among healthy pigs was 6.7% (4 out of 60). No apparent association was observed between PCR positive cases and any type of histopathological lesion. The phylogenetic analysis of the partial genome sequences obtained showed high identity among viruses from the three groups of animals studied. In conclusion, PCV‐3 was present in the serum of diseased and healthy pigs to similar percentages, suggesting that this virus does not seem to be causally associated with respiratory or enteric disorders.

Lack of Porcine circovirus 4 Genome Detection in Pig Samples from Italy and Spain

“…Particularly, 73 individual swine serum samples were obtained from 4-week-to 4-month-old pigs clinically diagnosed with respiratory signs (including interstitial/necrotizing pneumonia and pleuritis) (n = 30), and animals displaying enteric signs like atrophy-fusion of villi and catarrhal enteritis (n = 30) as well as healthy animals (n = 13). These samples were part of a set processed in a previously published article (Saporiti et al, 2020) [13]. Fifteen fetal tissue samples (eight from brains and seven from lungs) were also analyzed.…”

Genetic diversity and prevalence of porcine circovirus type 3 (PCV3) and type 2 (PCV2) in the Midwest of the USA during 2016–2018

“…Also, higher PCV3 infection rates have been reported in animals with digestive and respiratory diseases (Qi et al, ). However, not all studies support the putative role of PCV3 as a major threat to swine health (Franzo et al, ; Kim et al, ; Saporiti et al, ). Prevalence data presented here do not support the positive association of PCV3 infection with enteric‐disease‐causing or respiratory‐disease‐causing viral infections.…”

Detection of Porcine Circovirus 3 in Wildlife Species in Spain

“…According to previous studies, PCV-3 has been identified in different mammalian wild species such as wild boars and wild ruminants [12][13][14][15]. Interestingly, the frequency of the detection of viral DNA in wild boars originating from different European countries can be even higher (ranging from 23% and 50%) than the one reported in domestic pigs (from 6% to 32%) [2,[7][8][12][13][14][15][16][17]. This high prevalence in wild boars was predictable, since wild boars and domestic pigs pertain to the same species, and most of the infectious agents infecting the domestic pigs are also circulating in the wild boars [18,19].…”

“…DNA extraction was performed from 200 µL of serum sample by using MagMAX™ Pathogen RNA/DNA kit (Applied Biosystem®). The presence of PCV-3 DNA was assessed by means of a conventional PCR assay detecting a 418-bp fragment of replication gene as previously described (Saporiti et al, 2019) [7]. Briefly, the 25 µL reaction volume contained 2.5 µL of extracted DNA, 12.5 µL of Go Taq®G2 Green Master Mix (Promega), 1 µL of each primer (10 µM), and 8 µL of sterile water.…”

“…Porcine circovirus 2 (PCV-2) is the most economically important family member as it can cause the so-called porcine circovirus diseases (PCVD) [4]. Porcine circovirus 3 (PCV-3) has been identified not only in pigs experiencing different pathological conditions, e.g., respiratory and reproductive problems, porcine dermatitis and nephropathy syndrome (PDNS), myocarditis, and congenital tremors, but also in clinically healthy pigs [5][6][7][8]. Finally, the recently described porcine circovirus 4 (PCV-4), so far only in China, was detected in animals with respiratory disease, diarrhea or PDNS-like lesions [9].…”