Immune response against M protein-conserved region peptides from prevalent group A Streptococcus in a North Indian population.

[acute rheumatic fever]

Group A streptococci (GAS ) cause infections with a high prevalence in most developing countries . A GAS vaccine under trial that is based on the amino-terminus of the M protein provides type -specific immunity , and hence seems ineffective in India because of heterogeneous emm types . However , the conserved C-terminal region of the M protein protects against multiple serotypes . In this paper , the immune response generated against the conserved C-repeat region of the M protein was checked in an Indian population to establish their vaccine candidature .When screened for GAS , patients with pharyngitis , rheumatic fever /rheumatic heart disease (RF /RHD ), and invasive disease showed heterogeneous emm types , out of which five prevalent types (1 -2 , 11 , 49 , 75 and 112 ) were selected for the study . The C-terminal region of their M proteins showed conserved C 1 -, C 2 -, and C 3 -repeats . The C 1 -repeat was more diverse and had two different J 14 -like sequences . Peptides to these C-terminal regions (J 14 .1 and J 14 -R 6 ) were designed . Antibodies against these peptides were analyzed using the sera of 130 GAS -infected volunteers .Serum antibodies were significantly higher in patients with acute rheumatic fever , RHD , and invasive disease than in patients with pharyngitis or the healthy controls . The serum antibodies to these peptides was higher in teenagers and adults than in children .Results showed an association between streptococcal disease progression and the age-related development of immunity to the conserved regions . Hence , these peptides could be considered protective in impeding streptococcal infections worldwide .

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acute rheumatic fever

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