Group A streptococcal antigens and vaccine potential.

Attempts over the past seventy years to produce an effective vaccine to protect humans against group A streptococcal infections and their immunologically mediated sequelae (acute rheumatic fever and post-streptococcal glomerulonephritis) have been frustrated by two basic problems, first, the ability of the highly protective cell-surface M proteins to elicit potentially harmful host reactions and second, the existence of a large number of distinct serovars of M proteins and the fact that human immunity to group A streptococcal infections is predominantly M serovar-specific. In recent years, progress towards overcoming these problems has been greatly facilitated by an increased understanding of the structural and immunological properties of protective group A streptococcal antigens, which has emerged from molecular biology studies. This article reviews these studies and discusses the potential for developing an effective group A streptococcal vaccine.