Mycoplasma mycoides ssp. mycoides Biotype Small Colony‐Secreted Components Induce Apoptotic Cell Death in Bovine Leucocytes

Abstract

Contagious bovine pleuropneumonia, caused by Mycoplasma mycoides ssp. mycoides biotype small colony (MmmSC), is one of the most serious cattle diseases in Africa. Several observations suggested that MmmSC had evolved an efficient way to escape the bovine immune responses by triggering host-cell cytotoxicity. This study was implemented to determine whether the cytotoxic effect was due to apoptotic cell death. To that end, bovine blood cells were cultured for up to 3 days in the presence of viable or heat-killed MmmSC compared to unstimulated cultures. The findings provided evidence for a viable MmmSC-induced, timedependent apoptosis in bovine blood leucocytes, whereas heat-killed MmmSC had no effect. Morphological and physiological changes (evidenced by TUNEL and annexin V staining) typical of apoptosis were observed in response to viable MmmSC. All the lymphocyte subsets as well as the monocyte/granulocyte subset exhibited extensive apoptosis after exposure to viable MmmSC. Our results demonstrated a potential role for MmmSC-secreted components as pathogenic factors able to induce programmed cell death in bovine blood leucocytes.

Analysis of cellular responses toMycoplasma mycoidessubsp.mycoidessmall colony biotype associated with control of contagious bovine pleuropneumonia

“…Live mycoplasmas have been detected in draining lymph nodes of MmmSC-infected animals [1,23] and have shown, recently, to induce apoptosis of lymphocytes in vitro [9]. In this study, impaired in vitro responses of animals developing acute CBPP was not due to an intrinsic lack of responsiveness of their lymphocytes as indicated by control experiments with the mitogen ConA (not shown).…”

The immune response of bovine mammary epithelial cells to live or heat-inactivated Mycoplasma bovis

“…For Mycoplasma mycoides subsp. mycoides, it was previously shown that heat-inactivation results in impaired cytotoxicity (Dedieu et al, 2005). The main reason for this difference is that cell wall containing bacteria have components like lipoteichoic acid, peptidoglycans, or lipopolysaccharide that are recognized by the host immune system, whereas wall-less mycoplasmas do not have these classical virulence factors.…”

Expression and Immunogenicity of the Mycobacterial Ag85B/ESAT-6 Antigens Produced in Transgenic Plants by Elastin-Like Peptide Fusion Strategy

“…Peripheral blood mononuclear cells (PBMCs) were collected by density gradient centrifugation as previously described [53]. Bovine monocyte-derived dendritic cells (Bo-Mo-DC) were prepared from CD14-expressing cells using 40 ng/mL of both bovine recombinant IL-4 and GM-CSF as described in [54].…”