HISTO-PATHOLOGICAL FINDINGS AS AN AID TO EVALUATE THE EFFICACY OF A PRRS MODIFIED LIVE VIRUS VACCINE (US-STRAIN) AGAINST THE INFECTION BY A VIRULENT PRRS VIRUS (EU-STRAIN)

摘要

Since the initially description of porcine reproductive and respiratory syndrome virus (PRRSV) the pathology of the disease is described in its variety. Gross lesions associated with PRRSV infection vary widely, from none to diffuse tan consolidationand may depend on the virulence of the virus isolate and other factors. Light microscopic lesions in lungs can vary quantitatively in severity but are qualitatively similar. Therefore histo-pathological lung lesions seems to be a parameter which can be used in challenge studies to evaluate the efficacy of a vaccine also if the challenge virus does not induce gross lesions. In the frame of a clinical PRRSV vaccine efficacy study, histo-pathological investigation of the offspring was conducted to test the relevance of such findings for the evaluation of vaccine efficacy.