Evaluation of protection against bovine viral diarrhea virus type 2 after vaccination of the calves with bovine viral diarrhea virus type 1 combo inactivated vaccine

ABSTRACT This study was designed to evaluate the extent of the protection for bovine viral diarrhea virus type 2 (BVDV-2) infection, afforded by vaccination with a combo inactivated vaccine, which contains bovine viral diarrhea virus type 1 (BVDV-1) and infectious bovine rhinotracheitis virus (IBRV). Five 3-4-month-old calves were intramuscularly vaccinated with a single dose of the combo vaccine and boosted with same dose three weeks after the first vaccination, with five mock immunized calves serving as a control group. Twenty-one days after the second vaccination, all calves were challenged with BVDV-2 SX08 strain by spray into nostril. The unvaccinated animals developed typical clinical signs of high rectal temperature, diarrhoea with erosions and a dramatic drop in leukocyte counts. These signs occured markedly less in all vaccinated animals, the rectal temperature, leukopenia and virarmia of which, were significantly less than the mock immunized calves. It can be concluded that vaccination with the combo inactivated vaccine affords cross-protection against clinical effects of a challenge-infection with BVDV-2 SX08 strain, although it was part protection.

摘要 本研究旨在评估含牛病毒性腹泻病毒1型（BVDV-1）与牛传染性鼻气管炎病毒（IBRV）的联合灭活疫苗，对牛病毒性腹泻病毒2型（BVDV-2）感染的保护效力。选取5只3~4月龄犊牛，以单剂量肌内接种该联合疫苗，初免后3周以相同剂量加强免疫；另设5只空白免疫犊牛作为对照组。二免后21天，所有犊牛均经鼻腔喷雾接种BVDV-2 SX08毒株进行攻毒。结果显示，未免疫动物出现典型临床症状：直肠体温升高、伴糜烂性腹泻、白细胞计数显著下降；而免疫组动物的上述症状显著减轻，其直肠温度变化、白细胞减少症及病毒血症水平均显著低于空白免疫犊牛。综上，该联合灭活疫苗可对BVDV-2 SX08毒株攻毒后的临床症状提供交叉保护，尽管其仅能提供部分保护。