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Thursday, July 16, 1998
4:00 PM Eastern Time
Syphilis Genome Sequence Offers
Clues To Better Diagnosis, Prevention
Symptoms can be mild or absent in the early stages, and early symptoms
mimic those of many other diseases. Moreover, interpreting blood tests
can be difficult - the tests can give false negative results for up to
three months after infection - and repeated tests are often needed to
confirm the diagnosis. "For example, with the current screening test,
people who have yaws will test positive for syphilis," says Dr.
Hitchcock. "In addition, we need a specific test that will diagnose
Scientists can use the genetic blueprint for T. pallidum to devise
diagnostic tests that are more specific, more accurate and easier to
Syphilis is treated with injections of penicillin or other antibiotics.
About 10 percent of the population is allergic to penicillin; others do
not respond to the usual doses and may need repeated injections.
Easy-to-administer treatments that do not require an injection are
needed, especially for use in developing countries.
The genetic blueprint for the syphilis bacterium suggests targets for
new, more specific antibiotics.
As for other sexually transmitted diseases, preventing syphilis requires
constant vigilance, such as using condoms during intercourse and
avoiding contact with an infected person's open sores. Moreover, for
syphilis as well as some other sexually transmitted diseases, the male
condom is only partially protective. That is because the sores can be
in places that are not covered by the condom.
Thus preventing syphilis requires extensive screening and treatment. A
vaccine would be the easiest, most practical and effective method of
prevention, and is especially needed to prevent new infections in
high-risk U.S. populations and in developing countries.
The genome sequence for T. pallidum reveals the existence of 12 membrane
(surface) proteins that could be tested in experimental vaccines. One
or more of these surface components might stimulate the immune system to
respond to an invasion of T. pallidum when an uninfected person is
exposed to syphilis.
"The genome sequence represents an encyclopedia of information on this
elusive bacterium," says Dr. Weinstock. "We can now figure out ways to
disarm its defenses through vaccines, identify it quickly through new
diagnostic tests and eliminate it with specific, targeted antibiotics."
NIAID is a component of the National Institutes of Health (NIH). NIAID
conducts and supports research to prevent, diagnose and treat illnesses
such as HIV disease and other sexually transmitted diseases,
tuberculosis, malaria, asthma and allergies. NIH is an agency of the
U.S. Department of Health and Human Services.
Press releases, fact sheets and other NIAID-related materials are
available on the Internet via the NIAID web site at
CM Fraser, et al. Complete genome sequence of Treponema pallidum, the
syphilis spirochete. Science 281:375-387 (1998).