Immunohistopathology of Calf Pneumonia Induced by Endobronchial Inoculation with Bovine Adenovirus 3

Abstract

Abstract. Three 1-week-old and three 3-month-old Holstein calves that had received colostrum were inoculated endobronchially with bovine adenovirus 3 (BAV-3). The gross and histologic lesions in these six infected calves were localized mainly in the right caudal lobe of the lung and were closely associated with the site of the deposition of the inoculum. The pneumonic lesions were severe necrotizing bronchitis, bronchiolitis, and alveolitis, accompanied by infiltration of inflammatory cells and proliferation of type 2 pneumocytes. Intranuclear inclusion bodies, BAV-3 antigen, and virus particles were detected in the degenerated epithelial cells in the 1-week-old but not the 3-month-old calves. After infection, the total cell count in the bronchoalveolar lavage (BAL) fluid cells was increased. The results of BAV-3 isolation from BAL fluid were correlated with the detection of intranuclear inclusion bodies in the desquamated epithelial cells in the BAL fluid cells from the right caudal lobe but not in cells from the left caudal lobe. CD8ϩ T lymphocytes in the pneumonic lesion were found only in the 3-month-old infected calves. The difference in the immunopathologic reactions between the 1-week-old and the 3-month-old infected calves may be attributed to differences in immune system development.

Bovine Adenovirus Type 3 Pneumonia in Dexamethasone-treated Calves

“…These results are similar to those found in the case of colostrum-deprived calves infected on the day of birth with BAV-3 and in EB-infected 7-day-old calves. [5][6][7]19 The second type of pneumonic lesions were those associated with intrastitial pneumonia with severe cellular infiltration and were similar to those found in 3-month-old calves EB infected with BAV-3 or colostrum-deprived calves infected with trypsin-treated BAV-3, or both. 5,9,11,19 In recent studies, examination of BAL fluid cells has been used as a technique for understanding the pathophysiology of respiratory diseases.…”

“…[5][6][7]19 The second type of pneumonic lesions were those associated with intrastitial pneumonia with severe cellular infiltration and were similar to those found in 3-month-old calves EB infected with BAV-3 or colostrum-deprived calves infected with trypsin-treated BAV-3, or both. 5,9,11,19 In recent studies, examination of BAL fluid cells has been used as a technique for understanding the pathophysiology of respiratory diseases. [17][18][19] In the present study, the total cell count of BAL fluid cells from the right caudal lobe increased after BAV-3 infection, and the cells consisted of neutrophilic and desquamated epithelial cells containing intranuclear inclusion bodies.…”

“…[3][4][5][6][7]9,19,25 In the present study, pneumonic lesions were divided into two types. The first type was characteristic of severe necrotizing bronchiolitis with numerous intranuclear inclusion bodies and was found in non-DM-treated 7-day-old infected calves and in DM-treated 1.5-month-old infected calves.…”

“…5,9,11,19 In recent studies, examination of BAL fluid cells has been used as a technique for understanding the pathophysiology of respiratory diseases. [17][18][19] In the present study, the total cell count of BAL fluid cells from the right caudal lobe increased after BAV-3 infection, and the cells consisted of neutrophilic and desquamated epithelial cells containing intranuclear inclusion bodies. Detection of BAV-3 antigen was closely associated with the presence of intranuclear inclusion bodies in the degenerated epithelial cells.…”

“…Anti-BAV-3 rabbit serum was used as the primary antibody at a dilution of 1 : 8,000. 19 The presence of antibovine IgG, IgM, and IgA in the pneumonic lesions in paraffin sections was demonstrated using a simple stain MAXPO kit (Nichirei Corp.). Rabbit antibovine IgG-Fab fragment (Bethyl Laboratories Inc., Montgomery, TX), rabbit anti-IgM mu chain specific (Bethyl Laboratories Inc.), and rabbit antibovine IgA-alpha chain specific (Bethyl Laboratories Inc.) were used as the primary antibodies at a dilution of 1 : 2,000 each.…”