Preparation of polyclonal antibodies against chemically synthesized ApxIA and ApxIVA toxins and their diagnostic efficacy in the experimentally injected mice

Abstract

ObjectivesApxIA and ApxIVA are the main virulence factors of Actinobacillus pleuropneumoniae (A. pleuropneumoniae). The preparation of their antibodies is of great significance for diagnosing and treating porcine pleuropneumonia. MethodsThis study used chemically synthesized ApxIA and ApxIVA peptides as immunogens to prepare polyclonal antibodies against ApxIA and ApxIVA. Their titers were determined by ELISA and Dot blotting. Histopathology of apparently infected organs was carried out. Finally, the immunofluorescence method detected the distribution of antigens in the visceral tissues of mice infected with ApxIA and ApxIVA toxins. ResultsThe results showed that ApxIA and ApxIVA polyclonal antibodies with titer as high as 1: 200000 and 1: 50000, respectively, were successfully obtained. The immunofluorescence results showed that these polyclonal antibodies could accurately detect ApxIA and ApxIVA antigens in mouse lungs with strong specificity. Histopathologically, there were perialveolar hemorrhages, pulmonary emphysema, and sloughing of bronchiolar epithelium. There was vacuolation and infiltration of chronic inflammatory cells in the liver parenchymal tissue. Atrophy of intestinal villi and glands and sloughing of villus epithelium, and congestion. There was increased urinary space and congestion in the proximal convoluted tubules. Lymphoid follicles increased in size in the spleen, the germinal center enlarged, and congestion in surrounding lymphoid tissue were observed. ConclusionThis study laid a foundation for the research and development of a rapid detection kit for A. pleuropneumoniae and provided conditions for diagnosing and treating porcine contagious pleuropneumonia.