Carvalho L F, Segalés J, Pijoan C
UNESP-Departamento de Clínica e Cirurgia, Jaboticabal, Sao Paulo, Brazil.
Vet Microbiol. 1997 Apr;55(1-4):241-6. doi: 10.1016/s0378-1135(96)01324-7.
This trial was conducted to evaluate the effect of Porcine reproductive and respiratory syndrome virus (PRRSv) on a subsequent challenge with Pasteurella multocida in pigs. Sixteen, 3-4 week-old piglets, from a PRRSv and Aujeszky disease virus (ADV) free herd were used. Animals were equally and randomly allocated in four groups which were treated according the following schedule: Group I: negative controls; Group II: inoculation with only PRRSV; Group III: inoculation with PRRSV and P. multocida; Group IV: inoculation with ADV and P. multocida (positive controls). PRRSV and ADV were inoculated intranasally, at the doses of 10(4.6) and 10(4.5) TCID50/ml, respectively. Five days later, pigs from groups III and IV were inoculated intranasally, with two ml of a 10(9) CFU/ml suspension of equal parts of P. multocida, strains A52 and A24. No lesions were observed in piglets of group I. Microscopically, interstitial pneumonia was identified in all piglets of groups II and III and 3/4 piglets from group IV. Bronchopneumonia was detected in 3/4 of the piglets from group III and in all animals of group IV which, additionally, showed meningo-encephalitis and purulent rhinitis. Macroscopically, only piglets of groups III and IV had lung consolidation. However, much lower pneumonic scores (2.3%) were observed in group III, where 3 of 4 piglets were affected. On the other hand, all piglets of group IV showed some degree of pulmonary consolidation, with a mean score of 13.7%. Based on these results, it appears that the role of PRRSV as a initiator of secondary diseases is still undefined, but is probably mild. There was no clear interaction between PRRSv and Pasteurella multocida under the conditions and strains tested here.
本试验旨在评估猪繁殖与呼吸综合征病毒（PRRSv）对猪随后感染多杀性巴氏杆菌的影响。选用了16头3 - 4周龄的仔猪，来自无PRRSv和伪狂犬病病毒（ADV）的猪群。将动物平均随机分为四组，按以下方案进行处理：第一组：阴性对照；第二组：仅接种PRRSV；第三组：接种PRRSV和多杀性巴氏杆菌；第四组：接种ADV和多杀性巴氏杆菌（阳性对照）。PRRSV和ADV分别通过滴鼻接种，剂量分别为10(4.6)和10(4.5) TCID50/ml。五天后，第三组和第四组的猪通过滴鼻接种2ml由多杀性巴氏杆菌A52和A24菌株等量混合制成的10(9) CFU/ml悬液。第一组仔猪未观察到病变。显微镜下，第二组和第三组的所有仔猪以及第四组的3/4仔猪出现间质性肺炎。第三组3/4的仔猪和第四组的所有动物检测到支气管肺炎，此外，第四组动物还出现脑膜脑炎和脓性鼻炎。宏观上，只有第三组和第四组的仔猪出现肺实变。然而第三组肺实变程度低得多（2.3%），该组4头仔猪中有3头受影响。另一方面，第四组所有仔猪均出现一定程度的肺实变，平均评分为13.7%。基于这些结果，PRRSV作为继发性疾病引发剂的作用似乎仍不明确，但可能较轻。在此测试的条件和菌株下，PRRSv与多杀性巴氏杆菌之间没有明显的相互作用。
