Whooping cough evolving in a superbacterium

Australia needs a new pertussis vaccine to ensure that our most vulnerable are protected from the emergence of strains of superbugs, as demonstrated by new UNSW research.

The current vaccine, widely used since 2000, targets three antigens in the highly contagious respiratory disease bacteria that can be fatal to babies.

All infants under six months, in particular, newborns who are not protected by maternal immunization, are at risk of getting the vaccine-preventable disease because they are too small to get vaccinated or have not completed the primary vaccine cycle. three doses .

The Australian whooping cough epidemic from 2008 to 2012 saw more than 140,000 cases, with a peak of almost 40,000 in 2011, and revealed the increase in evolving strains capable of evading the immunity generated by the vaccine.

In a series of UNSW studies, with the latest published today in VaccineThe UNSW researchers took this knowledge further and demonstrated, in a world-class discovery, that the evolving strains made additional changes to better survive in their host, regardless of that person’s vaccination status. They also identified new antigens as possible vaccine targets.

The first author and microbiologist, Dr. Laurence Luu, who led the team of researchers with Professor Ruiting Lan, said that the ability of whooping cough to adapt to vaccines and survival in humans could be the answer to its surprising resurgence despite high vaccination rates in Australia.

“We discovered that whooping cough strains were evolving to improve their survival, regardless of whether a person was vaccinated or not, by producing more binding and nutrient transport proteins, and less immunogenic proteins that are not the target of the vaccine.” said Dr. Luu.

“This allows pertussis bacteria to more efficiently eliminate host nutrients during infection, as well as evade the body’s natural immune system because bacteria are producing less protein than our body recognizes.”

“In a nutshell, the bacteria that cause whooping cough are becoming better for hiding and for feeding, they are transforming into a superbug.”

Dr. Luu said that, therefore, it was possible for a vaccinated person to contract pertussis bacteria without the symptoms materializing.

“Then, the bacteria could still colonize you and survive without causing the disease; you probably wouldn’t know that you are infected with whooping cough bacteria because you don’t have the symptoms,” he said.

“Another problem with the vaccine is that immunity decreases rapidly, so we need a new vaccine that can better protect against evolving strains, stop disease transmission and provide more lasting immunity.”

Vaccination is still key, but a new vaccine is needed

Professor Lan said that although he would like to see a new vaccine developed and introduced in the next five to 10 years, the important discovery of the research team did not make Australia’s pertussis vaccine redundant.

“It is essential that people get vaccinated to prevent the spread of whooping cough (the current vaccine is still effective in protecting against the disease), but new vaccines must be developed in the long term,” said Professor Lan.

“We need more research to better understand the biology of pertussis bacteria, how they cause diseases and what proteins are essential for bacteria to cause infection, so that we can focus these proteins on a new and improved vaccine.”

“All this will help prepare new future-proof vaccines against evolving pertussis strains.”

Dr. Luu agreed that it was crucial that Australia maintain its high pertussis vaccination coverage.

“Although the number of cases of pertussis has increased over the past decade, it is still not as high as before the introduction of pertussis vaccines,” said Dr. Luu.

“Therefore, we emphasize that Australia must maintain its high vaccination coverage to protect vulnerable newborns who are not protected by maternal immunity and cannot complete the three-dose primary vaccine cycle until they are six months old “.

“Therefore, vaccination is especially important for children, people who are in contact with children and pregnant women who need the vaccine to produce antibodies to protect their newborns from developing pertussis in the first weeks of life.” .

In addition to babies under six months who have a high risk of contracting the disease, the elderly, people who live with someone who has pertussis, and people who have not had a booster in the last 10 years, are also older risk.

Pertussis is characterized by a “pertussis” sound and patients have difficulty breathing.

The disease is more common during spring and spreads when an infected person coughs or sneezes and other people breathe the bacteria.

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