Bactericidal activity of M protein conserved region antibodies against group A streptococcal isolates from the Northern Thai population

Background  

Most group A streptococcal (GAS) vaccine strategies have focused on the surface M protein, a major virulence factor of GAS. The amino-terminus of the M protein elicits antibodies, that are both opsonic and protective, but which are type specific. J14, a chimeric peptide that contains 14 amino acids from the M protein conserved C-region at the carboxy-terminus, offers the possibility of a vaccine which will elicit protective opsonic antibodies against multiple different GAS strains. In this study, we searched for J14 and J14-like sequences and the number of their repeats in the C-region of the M protein from GAS strains isolated from the Northern Thai population. Then, we examined the bactericidal activity of J14, J14.1, J14-R1 and J14-R2 antisera against multiple Thai GAS strains.