Summary
Macrophages are pivotal cells of the immune system and play a key role in the host defence mechanism against pathogens. To date, the importance of macrophages and the role of humoral response in eliciting macrophage activity against Mycoplasma mycoides subsp. mycoides small colony (Mmm‑SC), the causative agent of contagious bovine pleuropneumonia (CBPP), have only been marginally elucidated or are almost unknown. The present study was undertaken to investigate the changes in surface morphology of macrophages after in vitro infection with Mmm‑SC in the presence of bovine immune serum. Morphological analysis was performed on macrophage cultures at 6 h post infection using the three-dimensional vision of scanning electron microscopy. Non-infected macrophages in the presence of negative or immune serum and macro phages infected with Mmm‑SC in the absence of serum showed only minor cell surface changes. In contrast, clear surface modifications, broad veils, fine philopodia highlighting cell activation and small aggregates of mycoplasma closely attached to the macrophage membrane, were observed in infected macrophage cultures in the presence of immune serum. Our results suggest that specific humoral response to Mmm‑SC may contribute and support phagocytic activity of macrophages.

Keywords
Contagious bovine pleuropneumonia, IgG,IgM, Immunoblotting, Macrophage, Mycoplasma, Mycoplasma mycoides subsp. mycoides small colony, Scanning electron microscopy.