None of 14 calves not previously exposed to BVDV became infected after being forced to have nose-to-nose contact with a group of 5 calves primarily infected with BVDV. These were 5 male calves primarily infected with a type I BVDV strain, after nose-to-nose contact with a persistently viraemic calf. All 5 became infected and were clinically affected. They were slightly depressed and pyretic at 8-9 days post-infection, with a body temperature of up to 41.6 degrees C, but no medical treatment was required. Seroconversions to BVDV were detected in these calves at 14 to 21 days post-infection. The 14 healthy calves, proved to be free from BVD virus--as well as antibodies, were introduced 2 by 2 into the group of 5 primarily infected calves on days 4, 7, 14, 21, 28, 35 and 42 after the 5 calves had been in contact with the persistently BVDV-infected calf. Each pair of calves stayed within the primarily infected group for 2 days. None of these 14 calves seroconverted to BVDV.
Ingen av 14 seronegativa kalvar, som sattes i kontakt med en grupp kalvar primärinfekterade med BVDV, blev smittade med detta virus. Den primärinfekterade gruppen bestod av 5 jämngamla tjurkalvar som infekterades med BVDV genom art tvingas till nos mot nos kontakt med en persistent viremisk kalv. Samtliga 5 kalvar blev smittade med BVDV De hade 8 till 9 dagar efter smittillfallet lindrigt nedsatta all-mäntillstånd och feber upp till 41.6°C. Dock behövde inga medicinska behandlingar genomföras.
Antikroppar kunde påvisas i serum från och med 14 till 21 dagar efter smittillfället. Fjorton friska BVDV-negativa och seronegativa kalvar introducerades, 2 och 2, in i gruppen av primärinfekterade kalvar dag 4, 7, 14, 21, 28, 35 och 42 efter gruppens kontakt med den persistent viremiska kalven. Varje par kalvar stannade i gruppen 2 dagar och tvingades till nos mot nos kontakt med alla de primärinfekterade kalvarna. Ingen av dessa 14 kalvar serokonverterade mot BVDV.