Topic:M Protein
M protein is a structural component found in certain bacteria, notably Streptococcus species, which can affect horses. It is a surface protein that contributes to the bacterium's virulence by inhibiting phagocytosis, thereby allowing the bacteria to evade the host's immune system. In equine medicine, M protein is particularly relevant in the context of Streptococcus equi subsp. equi, the causative agent of strangles, a contagious upper respiratory tract infection in horses. Research on M protein in horses focuses on its role in pathogenesis, its potential as a target for vaccine development, and its utility in diagnostic testing. This page aggregates peer-reviewed research studies and scholarly articles that explore the molecular characteristics, immune response, and clinical implications of M protein in equine infectious diseases.
Strangles. The etiology, epizootiology, pathogenesis, and clinical presentation of strangles are described. Streptococcus equi, the causative organism, is highly host-adapted to Equidae and shows no antigenic variation. Protective immunity apparently is mediated by a combination of serum opsonic and nasopharyngeal mucosal humoral responses. Vaccines based on M protein or inactivated bacterial suspensions may reduce the clinical attack rate by 50%, a level of protection much lower than that produced during recovery from strangles.
Immunologically reactive proteins of Streptococcus equi. Immunologically reactive proteins in acid extracts and culture supernatants of Streptococcus equi were recognized through a combination of chromatographic and immunologic procedures. Both high- and low-molecular-weight components of each of these protein preparations were protective for mice and were, therefore, presumed to contain a variety of hydrolytic products or fragments of the M protein of S. equi. Convalescent horse sera that exhibited strong bactericidal activity for S. equi always reacted with polypeptides in the molecular weight range of 24,000 to 29,000, whereas preinfection sera d...
Regulation of the synthesis of M protein by sugars, Todd Hewitt broth, and horse serum, in growing cells of Streptococcus pyogenes. Various sugars were tested for their effect on the differential rate of synthesis of M protein during the growth of Streptococcus pyogenes strain 0055 M12T12. In a semisynthetic medium alone, a high rate of M protein synthesis occurred with glucose as a substrate; decreasing rates of synthesis occurred with sucrose and trehalose, in that order, although the rates of growth were approximately equal with all sugars. A period of derepressed synthesis of M protein occurred in the lag phase of growth and in the stationary period as the substrates were being depleted. Although glucose inhibited the ...