Lack of Virus Transmission from Bovine Viral Diarrhoea Virus Infected Calves to Susceptible Peers

Abstract

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 postinfection, with a body temperature of up to 41.6°C, but no medical treatment was required. Seroconversions to BVDV were detected in these calves at 14 to 21 days postinfection. 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.

Sammendrag

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.