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

Abstract

Porcine reproductive and respiratory syndrome (PRRS) is difficult to control due to a high mutation rate of the PRRS virus (PRRSV) and the emergence of virulent strains. The objective of this study was to analyse early and late pathological responses in the respiratory tract after infection with the European PRRSV subtype 3 strain Lena in comparison to two European PRRSV subtype 1 strains: Belgium A and Lelystad-Ter Huurne (LV). For each virus strain, groups of twelve pigs were inoculated, and four pigs per group were euthanized at days 3, 7 and 35 post-infection (p.i.) for consecutive examination. Infection with strain Lena resulted in a more severe disease than with the subtype 1 strains, an inflammatory response within the first week of infection with expression of IL-1α in the lung and lymph node, and an influx of neutrophils and monocytes in bronchoalveolar lavage fluid (BALF). Infection with strain Belgium A or LV resulted in mild or no pathology within the first week of infection, but inflammatory cell influx in the lung interstititium was increased at the end of the experiment at day 35 p.i. At five weeks p.i., all strains induced a higher percentage of cytotoxic T cells and higher levels of IFN-γ producing cells in BALF. This might have contributed to clearance of virus. In general, subtype 3 strain Lena induced a stronger early inflammatory response which led to more severe clinical disease and pathology. On the other hand, this may have supported an enhanced or faster clearance of virus in tissues, compared to subtype 1 strains.

Pathogenicity of three genetically diverse strains of PRRSV Type 1 in specific pathogen free pigs

“…In the present study, we compared clinical signs, virological parameters, seroconversion, APP response and histopathological lesions in pigs infected with either the Danish strain 18794 from subtype 1, the Russian strain ILI6 from subtype 2, and the Belarusian strain BOR59 from subtype 2, all belonging to PRRSV-1. The results indicated that BOR59 strain can be considered a highly virulent strain, similarly to subtype 3 strains Lena and SU1-bel (Karniychuk et al, 2010;Morgan et al, 2013;Weesendorp et al, 2013aWeesendorp et al, , 2014.…”

“…It has been shown that, in terms of virulence, antigenic characteristics and immunological responses following experimental infection, the Belarusian Lena subtype 3 strain differed from subtype 1 strains from Western Europe being generally more pathogenic for pigs (Karniychuk et al, 2010;Weesendorp et al, 2013aWeesendorp et al, , 2014. Later, another subtype 3 Belarusian strain SU1-bel, which was characterized in vitro and in in vivo challenge experiments also proved to be significantly more virulent than Western European strains (Morgan et al, 2014(Morgan et al, , 2013Salguero et al, 2015).…”

Heterogeneous antigenic properties of the porcine reproductive and respiratory syndrome virus nucleocapsid

“…SDOW17 is one of the most commonly used anti-N mAb which is considered to recognize N of nearly all European and North American PRRSV isolates except the PrimePac PRRS vaccine virus [31, 34, 40]. Accordingly, the SDOW17 mAb has been widely applied in immunohistochemistry [41, 42], immunofluorescence [43–45], virus titration [46], and flow cytometry [43, 47]. However, SDOW17 failed to detect the virus that caused the short PRRSV outbreak in Switzerland in 2012.…”

Elevated plasma-soluble CD16 levels in porcine reproductive and respiratory syndrome virus-infected pigs: correlation with ADAM17-mediated shedding

“…Although first reported over 25 years ago, PRRS remains a severe disease and causes huge economic losses in pig production worldwide (Meulenberg et al, 1993;Nathues et al, 2014;Tian et al, 2007;Tornimbene et al, 2015;Zhou & Yang, 2010). The most important pathological characteristics of PRRS are lung inflammation, loss of epithelial barrier function, immune cell migration, and increased vascular permeability (Han et al, 2014;Weesendorp et al, 2014). PRRSV mainly replicates in lungs, tonsils and lymphoid organs, and induces a persistent viral infection.…”