Uttenthal A, Le Potier M F, Romero L, De Mia G M, Floegel-Niesmann G
Danish Veterinary Institute for Virus Research, Lindholm, DK-4771, Kalvehave, Denmark.
Vet Microbiol. 2001 Nov 8;83(2):85-106. doi: 10.1016/s0378-1135(01)00409-6.
Two commercial marker vaccines against classical swine fever virus (CSFV) and companion diagnostic tests were examined in 160 conventional pigs. To test the vaccines in a "worst case scenario", group of 10 weaners were vaccinated using a single dose of an E2 (gp55) based vaccine at days -21, -14, -10 or -7, and subsequently challenged at day 0. The challenge virus was CSFV 277, originating from a recent outbreak of classical swine fever (CSF) in Germany. In all groups, only 5 out of 10 pigs were challenged; the remaining 5 pigs served as vaccinated contact controls. Also, three control groups, each consisting of 10 non-vaccinated pigs, were challenged in parallel to the vaccinated animals. CSFV could be isolated from all non-vaccinated pigs. Among these pigs 40% displayed a chronic course of the infection (virus positive for more than 10 days). Pigs vaccinated 21 or 14 days before challenge displayed no clinical signs of CSFV after challenge. However, they were still able to replicate CSFV when challenged, as measured by reisolation of CSFV from leukocytes of the directly challenged pigs. CSFV could be isolated from the leucocytes of 25% of the pigs vaccinated 21 days before challenge and 50% of the pigs vaccinated 14 days before challenge. Chronic infection was not observed, but transmission to one vaccinated contact pig occurred. From all pigs vaccinated 10 or 7 days before challenge, CSFV could be reisolated. We observed a chronic course of infection in 5% of pigs vaccinated 10 days before challenge and in 30% of pigs vaccinated 7 days before challenge. The mortality rate was 20% in the pigs vaccinated 10 days before challenge, and varied between 20 and 80% in pigs vaccinated 7 days prior to challenge. The contact animals had lower mortality (0-20%) than directly challenged pigs, probably mirroring the delayed time point of infection. There was thus some protection against clinical illness by both marker vaccines, but not a solid protection against infection and virus shedding. The efficacy of the vaccine was best if used 3 weeks before challenge and a clear correlation between time interval from vaccination to challenge and the level of virus shedding was observed. Each vaccine had its own accompanying discriminatory ELISA, but 18% of the virus positive pigs never seroconverted in these tests.
在160头常规猪中对两种针对经典猪瘟病毒（CSFV）的商用标记疫苗及配套诊断检测方法进行了检测。为在“最坏情况”下测试疫苗，将10头断奶仔猪分为一组，分别在第-21、-14、-10或-7天使用单剂量基于E2（gp55）的疫苗进行接种，随后在第0天进行攻毒。攻毒病毒为CSFV 277，源自德国近期爆发的经典猪瘟（CSF）疫情。在所有组中，每组仅10头猪中的5头接受攻毒；其余5头猪作为接种疫苗的接触对照。此外，三个对照组，每组由10头未接种疫苗的猪组成，与接种疫苗的动物同时进行攻毒。所有未接种疫苗的猪均能分离出CSFV。在这些猪中，40%呈现慢性感染病程（病毒阳性超过10天）。在攻毒前21天或14天接种疫苗的猪在攻毒后未表现出CSFV的临床症状。然而，通过从直接攻毒猪的白细胞中再次分离出CSFV来衡量，它们在攻毒时仍能够复制CSFV。在攻毒前21天接种疫苗的猪中，25%的猪白细胞中可分离出CSFV，在攻毒前14天接种疫苗的猪中，50%的猪白细胞中可分离出CSFV。未观察到慢性感染，但有一例病毒传播至一头接种疫苗的接触猪。在攻毒前10天或7天接种疫苗的所有猪中均能再次分离出CSFV。在攻毒前10天接种疫苗的猪中，5%呈现慢性感染病程，在攻毒前7天接种疫苗的猪中，30%呈现慢性感染病程。在攻毒前10天接种疫苗的猪中，死亡率为20%，在攻毒前7天接种疫苗的猪中，死亡率在20%至80%之间。接触动物的死亡率（0 - 20%）低于直接攻毒的猪，这可能反映了感染时间点的延迟。因此，两种标记疫苗都提供了一定程度的针对临床疾病的保护，但对感染和病毒排出没有可靠的保护作用。如果在攻毒前3周使用疫苗，疫苗效果最佳，并且观察到从接种疫苗到攻毒的时间间隔与病毒排出水平之间存在明显的相关性。每种疫苗都有其配套的鉴别ELISA，但18%的病毒阳性猪在这些检测中从未发生血清转化。
