Scientists Take One Step Closer in Developing Vaccine Against 'Flesh-Eating Bacteria'

Scientists at the University of California San Diego take one step closer in developing a vaccine against the dreaded bacteria that can cause "flesh-eating" disease and toxic shock syndrome as they uncover a hidden pattern in the outer protein of group A streptococcus.

Their discovery, described in the paper published in the journal Nature Microbiology, could be used to develop a vaccine that will not be limited to one M protein type and one strain of group A Strep, but will extend to most, if not all, M protein types and most, if not all strains, of group A Strep.

The main problem in developing a vaccine against the group A strep bacteria is the "hyper-variability of the M protein, a major surface of protein and virulence factor of the bacteria. Different strains of group A streptococcus have also different M protein. Due to this, our body's immune response can't launch an attack that is specific to the outer protein coat of the invading group A strep bacteria.

"When we become infected with a particular strain of group A Strep, we generally mount an immune response against the particular M protein displayed by that strain," explained Partho Ghosh, chair of UC San Diego's Department of Chemistry and Biochemistry and lead author of the paper, in a statement. "But this immunity works only against the infecting strain. We remain vulnerable to infection by other group A Strep strains that display other types of M proteins on their surfaces."

For the study, the researchers detailed four crystal structures of four different M protein types, each bounded to human protein called C4BP. By doing so, the researchers found the C4BP proteins are being recruited to the surface of group A Strep using common sequence patterns hidden within the differences that linked all these M proteins together.

With their findings, the researchers now are trying to develop a vaccine that will do the same thing as the C4BP, which could recognize many different M protein types. If made, the vaccine could protect humans against most, if not all, strains of group A streptococcus.