Dr. Pier and his colleagues purified the elusive molecule and injected it into rabbits. The rabbits produced large amounts of PNSG antibodies that persisted for at least eight months. The researchers then injected the PNSG antibodies into mice and exposed them to eight different strains of S. aureus, including strains resistant to the antibiotic methicillin and partially resistant to vancomycin. None of the animals developed an infection.
"Our findings suggest that this vaccine has the potential to provide immunity to the multi-drug resistant S. aureus 'superbug' that we have heard alarming reports of in the last year or so," says Dr. Pier.
"I think this work has a very good chance of being a major advance," says Stephen Heyse, M.D., medical bacteriology and antibacterial resistance program officer at NIAID. "It looks like a great vaccine candidate for Staphylococci, in general, both S. aureus and S. epidermidis."
Dr. Pier and his colleagues note that in addition to S. aureus, other bacterial species classified as coagulase-negative staphylococci, or CoNS, also produce PNSG.
"Together, S. aureus and CoNS account for 40 percent to 60 percent of bacterial blood isolates from hospitalized patients," says Dr. Pier. "Therefore, an additional potential advantage of a PNSG vaccine might be protection against the spectrum of clinically important CoNS."
Dr. Pier adds that he and his colleagues hope to move the PNSG vaccine into human trials soon, but predicts that such trials are one to two years away. They currently are negotiating licensing rights for the vaccine.
Other Ongoing NIAID S. Aureus Research
NIAID recently awarded a seven-year contract to MRL Pharmaceutical Services of
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Contact: John Bowersox
jbowersox@nih.gov
301-402-1663
NIH/National Institute of Allergy and Infectious Diseases
28-May-1999