Association of Porcine Circovirus Type 2 With Vascular Lesions in Porcine Pneumonia

Abstract

The aim of this study was to evaluate the vasculature in porcine circovirus type 2-infected (PCV2-infected) lungs and to identify the PCV2 subtypes involved in porcine pneumonia. Pulmonary samples from 140 pigs, 2 weeks to 7 months of age, from 36 Hungarian commercial herds with clinical signs of respiratory disease were examined for the presence of respiratory pathogens, with bacterial culture, pathologic evaluation, and immunohistochemistry for PCV2, porcine reproductive respiratory syndrome virus, and swine influenza virus. PCV2 was the most commonly identified pathogen (49 cases) among the 74 of 140 cases (53%) with respiratory pathogens. PCV2 was detected immunohistochemically in the wall of 13% to 100% of pulmonary vessels (mean, 89%) in 38 of 49 cases (78%). Detection of PCV2 antigen was positively correlated with the presence of vascular lesions (P < .001, odds ratio [OR]: 159.54). Other pathogens capable of vascular injury in swine were found in 29 of 49 of the PCV2-positive cases (59%). The probability of detecting vascular lesions in PCV2-infected lung was higher than in infection with porcine reproductive respiratory syndrome virus (P < .002, OR: 14.63), Pasteurella multocida infection (P < .001, OR: 5.75), or Streptococcus spp. infection (not significant, OR: 1.45). Sequence analysis of open reading frame 2 amplicons was possible in 6 PCV2-positive cases, from which 5 cases proved to be PCV2b subtype and 1 case, PCV2a subtype. In conclusion, PCV2 antigen was commonly colocalized with pulmonary vascular lesions in pneumonia in Hungarian swine, and PCV2b was the dominant subtype.

Vascular lesions and pneumonia in a pig fetus infected by porcine circovirus type 2

“…In this study, microscopic lesions were found only in the lungs, where multinucleated giant cells and prominent vascular lesions were detected first, with the parallel presence of nonsuppurative pneumonia. The presence of multinucleated giant cells in pig fetuses has so far been described only in the lymphoid organs (Opriessnig and Langohr, 2012) and vascular lesions have been reported only in growing and adult pigs with PMWS or PRDC (Opriessnig et al, 2006;Correa et al, 2007;Seeliger et al, 2007;Langohr et al, 2010;Szeredi et al, 2012;Resendes and Segalés, 2014). The presence of large amounts of PCV2 antigen in and around the blood vessels of different fetal organs suggests that the vascular system may be important in the pathogenesis of fetal PCV2 infection as well.…”

“…Formalin-fixed and paraffin-embedded tissue sections of 4 μm thickness were stained with haematoxylin and eosin (HE). Serial tissue sections were used for IHC in order to detect PCV2 as described by Szeredi et al (2012).…”

Biology and Diseases of Swine

“…Porcine Respiratory Disease Complex PCV2 was the most commonly identified pathogen in a study that examined porcine pneumonia, and detection of PCV2 positively correlated with vascular lesions, with PCV2b being the dominant subtype (Szeredi et al, 2012).…”

“…Pathogenesis Damage to the lymphoid system after infection is important in the pathogenesis of porcine respiratory disease complex (PRDC) (Szeredi et al, 2012). In vitro, activation of endothelial cells has been shown along with diminished coagulation time in vivo (Szeredi et al, 2012).…”

“…In vitro, activation of endothelial cells has been shown along with diminished coagulation time in vivo (Szeredi et al, 2012). Co-infection of animals with PCV2 and another pathogen occurs in most cases, and pathogenesis is thought to occur from virus-induced damage to the immune system (Szeredi et al, 2012). It is suspected that blood vessels play a role in PCV2 pathogenesis, but exact mechanism is not yet known (Szeredi et al, 2012).…”