Vaccine for Deadly Childhood Infection in the Works
The bacteria, called Neisseria meningitidis group B, is responsible
for most cases in the U.S. of the life-threatening infectious diseases
bacterial meningitis and septicemia, which occur most often in children and
"We have made such tremendous progress in the last year and a half that
we should be able to start testing a vaccine in humans by 2001. The process has
been moving so far, so fast and we want to keep the momentum," vaccine
designer Rino Rappuoli, PhD, says in an interview with WebMD. He and colleagues
from the Chiron Corp. in Siena, Italy, the Institute for Genomic Research in
Rockville, Md., and Oxford University in England described the vaccine
development process in two studies published in the March 10 issue of the
Bacterial meningitis (not to be confused with the less serious viral
meningitis) is an inflammation of the membranes that surround the brain and
spinal cord. It starts as a flu-like infection or sore throat, but within 24-48
hours after the first symptoms appear, it develops into a full-blown disease
with severe headache, a stiff neck, vomiting, fever, mental confusion, and, in
some cases, coma or death.
Septicemia, also called blood poisoning or bacteremia, is the presence of
bacterial infection in the bloodstream, marked by frequent and intermittent
high fever, shaking, and chills. In severe cases, the bloodstream can carry
bacteria to the brain, liver, or other organs. Both bacterial meningitis and
septicemia can be fatal unless patients get immediate hospitalization and
intensive treatment with antibiotics.
Many people (by some estimates, as many as 30%) are infected with the
bacteria that cause meningitis, which live in the throat without harming their
human host. But for unknown reasons, in a small percentage of people who harbor
the bacteria, it enters the bloodstream, crosses the blood-brain barrier that
normally protects the brain from infections, and sets up shop, rapidly
multiplying and causing the body to respond with an immune defense that causes
the severe inflammation and other symptoms associated with the disease.
Although vaccines are available to protect adults -- but not children --
from the devastating effects of meningitis caused by other forms of the
bacteria, group B meningitis strains have proved elusive. Vaccines work by
raising the body's natural antibodies to a protein or other feature that lies
on the surface of the invader (in this case, a bacteria). The antibodies then
move through the bloodstream looking for a specific intruder, using that
identifying protein -- much in the way that a beat cop will memorize the photo
of a wanted criminal. But group B meningitis strains are shape-shifters that
keep changing their appearance to evade capture by the immune system.
"The historical problem with trying to find a vaccine for this
particular strain [of bacteria] is the fact that almost everything on its
surface varies ... and that has made it very difficult to identify good vaccine
targets," researcher Derek W. Hood, PhD, says in an interview with WebMD.
Hood is with the Institute of Molecular Medicine at Oxford University and the
department of pediatrics at John Radcliffe Hospital in Oxford, England.