Highly pathogenic porcine reproductive and respiratory syndrome virus infection results in acute lung injury of the infected pigs

Abstract

Highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) was firstly characterized in 2006 in China. The virus has caused great economic loss to the Chinese swine production during the past years. Herein, we experimentally infected SPF pigs using two strains of PRRSV with different pathogenicity and observed the lung pathological changes looking for new sights on the possible pathogenesis associated with the virulence of HP-PRRSV. The results indicated that the HP-PRRSV-infected pigs died and exhibited severe pathological changes of lungs featuring increased neutrophils, mast cells and mononuclear macrophages, compared with the pigs inoculated with low pathogenic (LP-) PRRSV. Furthermore, the pigs infected with HP-PRRSV showed the higher levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, interleukin (IL)-8 and histamine, leukotriene B4 (LTB4), platelet activation factor (PAF) in sera than those inoculated with LP-PRRSV. Additionally, the fibrosis of lung was observed in the HP-PRRSV-infected pigs. At present, our findings suggest that the aberrant immune responses triggered by HP-PRRSV infection are closely related to acute lung injury (ALI), and especially the pathological changes in lung vascular system are of particular significance. These associated pathological changes of lung are in part responsible for the additional morbidity and mortality observed in HP-PRRSV infection.

Lung pathogenicity of European genotype 3 strain porcine reproductive and respiratory syndrome virus (PRRSV) differs from that of subtype 1 strains

“…The strain Lena-infected pigs induced higher levels of the proinflammatory IL-1b and TNFa mRNA in blood cells (Weesendorp et al, 2013a,b) and a higher level of IL-1b mRNA expression in the lymph node and lung. A correlation between the pathogenicity of the strain and the expression of pro-inflammatory cytokines was also described by other authors (reviewed by Gó mez-Laguna et al, 2013;Han et al, 2014). In pigs infected with highly pathogenic PRRSV strains, clinical disease was related to severe interstitial pneumonia and high expression levels of pro-inflammatory cytokines like IL-1b and TNF-a in the lungs compared to less virulent PRRSV strains.…”

The therapeutic effects of sodium cromoglycate against influenza A virus H5N1 in mice

“…Pathological changes were observed and scored under an Olympus microscope (Olympus Optical Co., Ltd.). Criteria for grading changes were previously reported25 with some modifications: grade 0 = no obvious pathological changes; grades 1–3 = inflammatory cell infiltration, hemorrhage, cell shedding; grades 4–5 = inflammatory cell infiltration, hemorrhage, vasculitis or bronchiolitis, and cell apoptosis and necrosis; grades 6–10 = severe inflammatory cell infiltration, severe hemorrhage, vasculitis or bronchiolitis, obvious edema, cell apoptosis and necrosis, and microthrombosis.…”

An Update on the Epidemiology and Pathology of African Swine Fever

“…Pigs infected with HP-PRRS strains display high mortality accompanied by high fever (body temperature 40e42 C) severe lethargy, anorexia, cough, severe dyspnoea, lameness and cyanosis of the ears, limbs and perineum (Zhou et al, 2009;Han et al, 2014). The main lesions are found in the lungs, which display interstitial pneumonia (Han et al, 2014), and in lymphoid organs, where severe thymic atrophy and swelling and haemorrhage in the tonsils and lymph nodes may be observed (located in the medulla with a cut surface showing a marbled appearance), together with scattered infarcts or white spots on the surface of the spleen.…”

“…The main lesions are found in the lungs, which display interstitial pneumonia (Han et al, 2014), and in lymphoid organs, where severe thymic atrophy and swelling and haemorrhage in the tonsils and lymph nodes may be observed (located in the medulla with a cut surface showing a marbled appearance), together with scattered infarcts or white spots on the surface of the spleen. Petechial haemorrhages may be observed in the renal cortex (Wang et al, 2011).…”