Investigation of surfactant apoproteins and Brucella sp. antigens in the lungs of aborted bovine fetuses and neonatal calves delivered weak

Abstract

The main objectives of this study were to investigate surfactant apoprotein expression (SP) and to detect Brucella sp. antigens in the lungs of aborted bovine fetuses and neonatal calves delivered weak. The Avidin-Biotin-Peroxidase Complex (ABC) and the indirect immunofluorescence (IF) techniques were applied, using antibodies to the lung surfactant apoproteins (SP-A, SP-B, SP-C) and Brucella sp. antigens. Hyperplasia of type II cells was also assessed by evaluating Thyroid Transcription Factor-1 (TTF-1), Proliferating Cell Nuclear Antigen (PCNA), and Cytokeratin Pan Type I/II (CK-P) markers. The study materials were the lungs of 46 aborted bovine fetuses and 20 neonatal calves delivered weak. Brucella sp.-positive fetal lungs displayed bronchopneumonia in 24 cases. The lungs of the weak-delivered neonates which were positive for Brucella sp. also showed pneumonia. Bacterial culture detected positivity in 11 of 46 fetuses and two neonates. IHC for Brucella sp. antigens found positivity in 22 of 46 fetuses and four neonates. Thus, our research revealed that the IHC technique using anti-Brucella sp. antibodies was useful for detecting Brucella sp. in autolytic and culture-negative fetuses. The study also found that surfactant synthesis begins close to the 7th month of gestation in bovine fetuses. Immunolabeling to SPs occurred in the cytoplasm of both type II and Clara cells, along with SP-C only in type II pneumocytes. The IF yielded dense labeling for Brucella sp. antigens, SP-B, and CK-P, respectively, in the phagocytic cells and epithelium of the airways. Also, pneumonia in newborn calves indicates an intrauterine infection by Brucella sp.