REAL TIME RT-PCR ; A VERY SENSITIVE DIAGNOSTIC TOOL TO DETECT LOW POSITIVES IN A PRRS ERADICATION PROGRAMME.

摘要

A major PRRS outbreak occurred between October 2005 and January 2006 on a one-site, closed, large sow herd in northern Italy. Airborne spread also caused the infection of two neighbouring finishing sites Production was disrupted and returned to normallevels only in late spring 2006. At that time, in order to avoid future problems, it was decided to attempt a PRRS eradication programme using a combination of Herd Closure and Wean & Removal. All the animals on farm were blood sampled in weekly batchesstarting in week 2006-37 through week 2007-13. Based on combined results of PRRS Elisa serology (IDEXX HerdChek~R) and PCR, positive sows were culled either before farrowing (PCR pos.ve) or at weaning (serol. pos.ve with s/p values > 1,3). To save timeand to reduce costs during the 29 weeks of sampling it was decided to pool blood samples for PCR in fives. In order to avoid missing positives it was also decided to deliberately use a “very sensitive” Real Time RT -PCR technique instead of the conventional Onestep-PCR.