Foreyt W J, Silflow R M
Department of Veterinary Microbiology and Pathology, Washington State University, Pullman 99164-7040, USA.
J Wildl Dis. 1996 Apr;32(2):315-21. doi: 10.7589/0090-3558-32.2.315.
Between February and April, 1994, we tested the hypothesis that bighorn sheep (Ovis canadensis canadensis) inoculated with a cytotoxic isolate of Pasteurella haemolytica biotype A, serotype 11 (A11) could withstand challenge inoculation with a cytotoxic strain of P. haemolytica A2 of domestic sheep origin known to cause lethal pneumonia in bighorn sheep. On experimental day O, two bighorn sheep were inoculated intratracheally with 6 x 10(9) colony forming units (cfu) of a cytotoxic strain of P. haemolytica A11 (group 1); two bighorn sheep were inoculated intratracheally with 6 x 10(9) cfu of a noncytotoxic P. haemolytica A11 (group 2), and two control bighorn sheep were inoculated intratracheally with a similar volume of brain heart infusion (BHI) broth (group 3). After inoculation, all bighorn sheep remained healthy. On experimental day 16, group 1 bighorn sheep each were given the same intratracheal inoculation as on day O, and groups 2 and 3 bighorn sheep each were inoculated with BHI broth at the same volume as group 1. All bighorn sheep remained healthy following inoculations. On experimental day 42, bighorn sheep in groups 1 and 3 each were challenged with an intratracheal inoculation of 6 x 10(9) cfu of P. haemolytica A2 of domestic sheep origin known to be lethal in bighorn sheep. Group 2 sheep each were inoculated intratracheally with BHI broth at the same volume as groups 1 and 3. The four bighorn sheep in groups 1 and 3 that received the challenge inoculation died from acute bronchopneumonia within 72 hours after challenge inoculation, and cytotoxic P. haemolytica A2 was isolated from the four dead bighorn sheep. Both cytotoxic or noncytotoxic strains of P. haemolytica A11 were not lethal and did not cause pneumonia in the experimentally inoculated bighorn sheep. However, previous inoculation with cytotoxic P. haemolytica A11 did not protect the bighorn sheep against later experimental challenge inoculation with a known lethal strain of cytotoxic P. haemolytica A2 under the conditions defined in these experiments.
1994年2月至4月期间，我们对以下假设进行了验证：给大角羊（加拿大盘羊指名亚种，Ovis canadensis canadensis）接种溶血性巴氏杆菌生物型A血清型11（A11）的细胞毒性分离株后，其能否抵御接种源自家养绵羊的已知可在大角羊中引发致命性肺炎的溶血性巴氏杆菌A2细胞毒性菌株的攻击。在实验第0天，给两只大角羊经气管内接种6×10⁹集落形成单位（cfu）的溶血性巴氏杆菌A11细胞毒性菌株（第1组）；给两只大角羊经气管内接种6×10⁹ cfu的非细胞毒性溶血性巴氏杆菌A11（第2组），给两只对照大角羊经气管内接种相同体积的脑心浸液（BHI）肉汤（第3组）。接种后，所有大角羊均保持健康。在实验第16天，第1组大角羊每只接受与第0天相同的经气管内接种，第2组和第3组大角羊每只接种与第1组相同体积的BHI肉汤。接种后所有大角羊均保持健康。在实验第42天，第1组和第3组的大角羊每只经气管内接种6×10⁹ cfu源自家养绵羊的已知对大角羊具有致死性的溶血性巴氏杆菌A2进行攻毒。第2组的绵羊每只经气管内接种与第1组和第3组相同体积的BHI肉汤。接受攻毒接种的第1组和第3组中的四只大角羊在攻毒接种后72小时内死于急性支气管肺炎，且从这四只死亡的大角羊中分离出了细胞毒性溶血性巴氏杆菌A2。溶血性巴氏杆菌A11的细胞毒性或非细胞毒性菌株在实验接种的大角羊中均不具有致死性且未引发肺炎。然而，在这些实验所定义的条件下，先前接种细胞毒性溶血性巴氏杆菌A11并不能保护大角羊抵御后来用已知具有致死性的细胞毒性溶血性巴氏杆菌A2进行的实验性攻毒接种。
