Reverse vaccinology success story

Courtesy of Rocky Mountain Laboratories, NIAID, NIHIn a finding that further validates an emerging vaccine strategy, researchers in Italy and the United States have worked backward from genome to antigens to identify a protein cocktail that may confer global protection against group B streptococcus (GBS).1This discovery represents "one of the important ways in which the promise of genomics can be harnessed,"

By | August 1, 2005

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Courtesy of Rocky Mountain Laboratories, NIAID, NIH

In a finding that further validates an emerging vaccine strategy, researchers in Italy and the United States have worked backward from genome to antigens to identify a protein cocktail that may confer global protection against group B streptococcus (GBS).1

This discovery represents "one of the important ways in which the promise of genomics can be harnessed," says Victor Nizet of the University of California, San Diego, who did not participate in this study. The researchers compared the genomes of eight bacterial samples representing the five most important disease-causing GBS serotypes. They used a computer algorithm to identify genes coding for surface-exposed proteins and successfully expressed 312 of these in Escherichia coli. They then immunized female mice with these proteins, mated the mice, and challenged their pups with lethal doses of GBS. Four antigens stood out that significantly increased survival.

Only one of the four targets – the previously identified Sip antigen – was found in all the strains. But when all four were used in combination after challenge by strains representing all nine serotypes, 59% to 100% of the pups were protected. "If you want to think about developing a vaccine with global coverage," says study coauthor Lawrence Paoletti of Brigham and Women's Hospital in Boston, "you want to find a set of antigens, like the four we studied, that would give broad coverage."

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