Trivalent M-related protein as a component of next generation group A streptococcal vaccines.
OBJECTIVE
There is a need to broaden protective coverage of M protein-based vaccines against group A streptococci (GAS) because coverage of the current 30-valent M protein vaccine does not extend to allemmtypes. An additional GAS antigen and virulence factor that could potentially extend vaccine coverage is M-related protein (Mrp). Previous work indicated that there are three structurally related families of Mrp (MrpI, MrpII, and MrpIII) and peptides of all three elicited bactericidal antibodies against multipleemmtypes. The purpose of this study was to determine if a recombinant form containing Mrp from the three families would evoke bactericidal antiserum and to determine if this antiserum could enhance the effectiveness of antisera to the 30-valent M protein vaccine.


METHODS
A trivalent recombinant Mrp (trMrp) protein containing N-terminal fragments from the three families (trMrp) was constructed, purified and used to immunize rabbits. Anti-trMrp sera contained high titers of antibodies against the trMrp immunogen and recombinant forms representing MrpI, MrpII, and MrpIII.


RESULTS
The antisera opsonizedemmtypes of GAS representing each Mrp family and also opsonizedemmtypes not covered by the 30-valent M protein-based vaccine. Importantly, a combination of trMrp and 30-valent M protein antiserum resulted in higher levels of opsonization of GAS than either antiserum alone.


CONCLUSIONS
These findings suggest that trMrp may be an effective addition to future constructs of GAS vaccines.
Department of Medicine, Immunology and Biochemistry, The University of Tennessee Health Science Center, Memphis, TN, USA.; Department of Medicine, Veterans Affairs Medical Center, Memphis, TN, USA.
Harry S
0000-0002-6915-5014
HS
Courtney
Department of Medicine, Immunology and Biochemistry, The University of Tennessee Health Science Center, Memphis, TN, USA.; Department of Medicine, Veterans Affairs Medical Center, Memphis, TN, USA.
Shannon E
0000-0003-1804-7125
SE
Niedermeyer
Department of Medicine, Immunology and Biochemistry, The University of Tennessee Health Science Center, Memphis, TN, USA.; Department of Medicine, Veterans Affairs Medical Center, Memphis, TN, USA.
Thomas A
0000-0001-8819-8039
TA
Penfound
Department of Medicine, Immunology and Biochemistry, The University of Tennessee Health Science Center, Memphis, TN, USA.; Department of Medicine, Veterans Affairs Medical Center, Memphis, TN, USA.
Claudia M
0000-0001-9054-6047
CM
Hohn
Department of Medicine, Immunology and Biochemistry, The University of Tennessee Health Science Center, Memphis, TN, USA.; Department of Medicine, Veterans Affairs Medical Center, Memphis, TN, USA.
Adam
0000-0001-5526-0094
A
Greeley
Department of Medicine, Immunology and Biochemistry, The University of Tennessee Health Science Center, Memphis, TN, USA.; Department of Medicine, Veterans Affairs Medical Center, Memphis, TN, USA.; Department of Microbiology, Immunology and Biochemistry, The University of Tennessee Health Science Center, Memphis, TN, USA.
James B
0000-0001-9860-9233
JB
Dale
Streptococcus pyogenes; Vaccines; Virulence factors