responseControl pigs were clinically normal following sham challenge.Clinical differences between vaccinated and non-vaccinated chal-lenge groups and among challenge virus groups were observed. Inboth rJXwn06 challenge groups pigs became listless and anorexic1–2 dpc. Acute respiratory distress, characterized by dyspnea,tachypnea and coughing was common in rJXwn06 pigs beginning1–3 dpc. Intermittent erythema of the skin was present in mostof the pigs beginning 2–3 dpc, and several developed cutaneouspetechial hemorrhages and cyanotic extremities (blue ears). Ini-tially, pigs in the vaccinated group developed clinical signs andmortality sooner than the non-vaccinated pigs, but by 5–7 dpcthe groups were indistinguishable and from 8 to 14 dpc theVac/rJXwn06 group began to recover. In contrast, at 14 dpc theremaining rJXwn06 pigs were cachectic with most of them still hav-ing overt respiratory disease. Compared to the rJXwn06 challengedgroups the magnitude of clinical disease was less in the SRV07-challenged pigs with the non-vaccinated more affected than thevaccinated pigs. Moreover, onset of disease for both groups wasdelayed several days and no mortality occurred during the exper-iment although several of the non-vaccinated/rSRV07 challengepigs were moderately affected at the conclusion of the experi-ment suggesting that given time they may have succumbed tothe infection. There was mild disease in the VR2332 challengegroup recognized as increased respiration rates and intermit-tent anorexia beginning 4–5 dpc and lasting for about 7 days.No clinical disease was recognized in the Vac/VR2332 challengegroup.