Mdp. Boyle, VARIATION OF MULTIFUNCTIONAL SURFACE BINDING-PROTEINS - A VIRULENCE STRATEGY FOR GROUP-A STREPTOCOCCI, Journal of theoretical biology, 173(4), 1995, pp. 415-426
Variation in surface antigens has been well recognized as a mechanism
by which pathogenic organisms can avoid elimination and remain as pote
ntial pathogens in immunocompetent individuals. A variety of viral and
parasitic organisms elude the immune system by varying their surface
antigenic structures. Other persistent human pathogens, for example gr
oup A streptococci, are associated with cyclic variation in the severi
ty of infections without any major change in their surface antigenic s
tructures. Recent analysis of group A streptococcal proteins, in parti
cular surface M and M-like proteins, has documented the existence of a
n array of multifunctional surface proteins which have the ability to
bind to a variety of normal human plasma proteins, extracellular matri
x components and human cells. The ability to change the functional act
ivities of these surface molecules by genetic recombination among memb
ers of a closely related M protein supergene family has now been repor
ted. In this paper, the potential importance of generating functional
heterogeneity in surface binding proteins of group A streptococcus is
discussed. The role of these proteins in enabling an organism to sense
its environment and express the appropriate virulence factors is prop
osed as an explanation for the periodic changes in the frequency and s
everity of invasive group A streptococcal infections that can occur in
the absence of a toxic-shock-like syndrome.