Gonorrhoea researchers identify innovative vaccine, new antibiotic

By
Maxwell Awumah, GNA

Hohoe, July 07, GNA – Researchers
have identified a protein that powers the virulence of the bacteria that causes
gonorrhoea, opening the possibility of a new target for antibiotics and, even
better, a vaccine.

The findings,
published Friday in PLOS Pathogens, and copied to the Ghana News Agency, are
especially important since the microbe, Neisseria gonorrhoeae, is considered a
“superbug” because of its resistance to all classes of antibiotics
available for treating infections.

Gonorrhoea, a sexually
transmitted disease that results in 78 million new cases worldwide each year,
is highly damaging if untreated or improperly treated.

It can lead to
endometritis, pelvic inflammatory disease, ectopic pregnancy, epididymitis and
infertility. Babies born to infected mothers are at increased risk of
blindness.

“The infections
very often are silent,” said Oregon State University researcher Aleksandra
Sikora.

“Up to 50 percent
of infected women don’t have symptoms, but those asymptomatic cases can still
lead to some severe consequences for the patient’s reproductive health,
miscarriage or premature delivery.”

The need for better
antibiotic therapy, and a vaccine, is pressing. N. gonorrhoeae strains
resistant to the last effective treatment options have emerged, and failures in
treatment are occurring.

Dr Sikora and her
research team at the OSU/OHSU College of Pharmacy and Ann Jerse’s lab at the
Uniformed Services University of the Health Sciences in Bethesda, Maryland,
collaborated to discover a novel lipoprotein that N. gonorrhoeae uses can
defeat the body’s first line of innate immune defence.

It said the body
relied on enzymes known as lysozymes that, as their name suggests, thwart
bacteria by causing their cell wall to lyse, or break apart.

Lysozymes are abundant
both in epithelial cells, which make up the tissue on the outside of organs and
the inside of body cavities, and in the phagocytic cells that protect the body
by ingesting foreign particles and bacteria.

In turn, many
gram-negative bacteria — characterised by their cell envelope that include a
protective outer membrane — have developed ways of defeating lysozymes. Prior
to the work by Dr Sikora’s team, however, only one lysozyme-fighting protein
had been discovered in the Neisseria genus.

Now that new targets
had been identified, they could be explored as bullseye candidates for new
antibiotics or a vaccine — if the lysozyme inhibitor could itself be
inhibited, then the bacteria’s infection-causing ability is greatly reduced.

Dr Sikora and her
collaborators named the new protein SliC, short for surface-exposed lysozyme
inhibitor of c-type lysozyme.

Studying SliC’s
function in culture as well as in a gonorrhoea mouse model — mice were
infected with N. gonorrhoeae, then checked for SliC expression at one, three
and five days — researchers determined the protein was essential to bacterial
colonisation because of its anti-lysozyme role.

“This is the
first time an animal model has been used to demonstrate a lysozyme inhibitor’s
role in gonorrhoea infection,” Dr Sikora said.

“Together, all of
our experiments show how important the lysozyme inhibitor is. This is very
exciting.”

GNA

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