Ciszewski D K, Baker J C, Slocombe R F, Reindel J F, Haines D M, Clark E G
College of Veterinary Medicine, College of Veterinary Medicine, Michigan State University, East Lansing 48824-1314.
Vet Microbiol. 1991 Jun;28(1):39-60. doi: 10.1016/0378-1135(91)90098-z.
An experiment was conducted to reproduce respiratory tract disease with bovine respiratory syncytial virus (BRSV) in one-month-old, colostrum-fed calves. The hypothesized role of viral hypersensitivity and persistent infection in the pathogenesis of BRSV pneumonia was also investigated. For BRSV inoculation a field isolate of BRSV, at the fifth passage level in cell culture, was administered by a combined respiratory tract route (intranasal and intratracheal) for four consecutive days. Four groups of calves were utilized as follows: Group I, 6 calves sham inoculated with uninfected tissue culture fluid and necropsied 21 days after the last inoculation; Group II, 6 calves inoculated with BRSV and necropsied at the time of maximal clinical response (4-6 days after the last inoculation); Group III, 6 calves inoculated with BRSV and necropsied at 21 days after the last inoculation; Group IV, 6 calves inoculated with BRSV, rechallenged with BRSV 10 days after initial exposure, and necropsied at 21 days after the initial inoculation. Clinical response was evaluated by daily monitoring of body temperature, heart rate, respiratory rate, arterial blood gas tensions, hematocrit, total protein, white blood cell count, and fibrinogen. Calves were necropsied and pulmonary surface lesions were quantitated by computer digitization. Viral pneumonia was reporduced in each principal group. Lesions were most extensive in Group II. Disease was not apparent in Group I (controls). Significant differences (p less than 0.05) in body temperature, heart rate, respiratory rate, arterial oxygen tension, and pneumonic surface area were demonstrated between control and infected calves. Results indicate that severe disease and lesions can be induced by BRSV in one-month-old calves that were colostrum-fed and seropositive to BRSV. BRSV rechallenge had minimal effect on disease progression. Based on clinical and pathological response, results did not support viral hypersensitivity or persistent infection as pathogenetic mechanisms of BRSV pneumonia.
开展了一项实验，在1月龄初乳喂养的犊牛中用牛呼吸道合胞病毒（BRSV）诱发呼吸道疾病。还研究了病毒超敏反应和持续性感染在BRSV肺炎发病机制中的假定作用。对于BRSV接种，采用细胞培养传代至第5代的BRSV野外分离株，通过联合呼吸道途径（鼻内和气管内）连续4天给药。使用四组犊牛，具体如下：第一组，6头犊牛用未感染的组织培养液进行假接种，并在最后一次接种后21天进行剖检；第二组，6头犊牛接种BRSV，并在出现最大临床反应时（最后一次接种后4 - 6天）进行剖检；第三组，6头犊牛接种BRSV，并在最后一次接种后21天进行剖检；第四组，6头犊牛接种BRSV，在初次接触后10天再次用BRSV攻击，并在初次接种后21天进行剖检。通过每日监测体温、心率、呼吸频率、动脉血气张力、血细胞比容、总蛋白、白细胞计数和纤维蛋白原评估临床反应。对犊牛进行剖检，并通过计算机数字化对肺表面病变进行定量分析。在每个主要组中都再现了病毒性肺炎。第二组的病变最为广泛。第一组（对照组）未出现疾病。对照犊牛和感染犊牛在体温、心率、呼吸频率、动脉血氧张力和肺炎表面积方面存在显著差异（p < 0.05）。结果表明，BRSV可在1月龄初乳喂养且对BRSV血清学阳性的犊牛中诱发严重疾病和病变。再次感染BRSV对疾病进展影响极小。基于临床和病理反应，结果不支持病毒超敏反应或持续性感染作为BRSV肺炎的发病机制。
