UNASSIGNED: Porcine reproductive and respiratory syndrome (PRRS) continues to be the most economically important disease of @entity1707 worldwide. The appearance of highly pathogenic PRRS virus ( @entity23007 ) strains in Europe and Asia has raised concerns about this disease and initiated increased efforts to understand the pathogenesis. In this study, we have compared the pathology and the virus distribution in tissues of @entity1707 experimentally inoculated with three different genotype 1 @entity23007 isolates. Sixty 5-week-old @entity1707 were inoculated intranasally with a) the Lelystad virus (LV), b) a field strain from the UK causing respiratory clinical signs (UK) or c) a highly pathogenic strain from Belarus (BE). Sixteen animals were mock-infected and used as controls. The animals were euthanized at 3, 7 and 35  days post-infection (dpi), and lung and lymphoid tissues collected for histopathological examination and @entity23007 detection by immunohistochemistry (IHC). Histopathological lesions consisted of interstitial pneumonia with mononuclear cell infiltrates in the lungs, lymphoid depletion, apoptosis and follicular hyperplasia in the spleen, lymph nodes and tonsil and lymphoid depletion in the thymus. @entity23007 was detected mainly in monocytes-macrophages. BE-infected animals showed the highest pathological scores and the highest presence of virus at 3 and 7  dpi, followed by the UK field strain and then LV. Moderate lesions were observed at 35  dpi with lesser detection of @entity23007 by IHC in each infected group. The highly pathogenic BE strain induced more severe pathology in both lungs and lymphoid organs of @entity1707 compared with the classic field isolate and the prototype LV. The increased severity of pathology was in correlation with the presence of a higher number of @entity23007 -infected cells in the tissues.

Pathology and Virus Distribution in the Lung and Lymphoid Tissues of XXXX Experimentally Inoculated with Three Distinct Type 1 PRRS Virus Isolates of Varying Pathogenicity.

@entity1707 :: ('9823', 'Species') :: ['pigs', 'swine'] @entity23007 :: ('28344', 'Species') :: ['PRRSV', 'Porcine reproductive and respiratory syndrome virus']
@entity1707 :: (9823,Species) :: ['Pigs']
