Natures wonders: pathogenic bacteria hide in plain sight (Introduction)

by David Turell @, Wednesday, December 04, 2019, 05:24 (211 days ago) @ David Turell

A. strep can cling to familiar material and the immune system can't find them:

"Much of how group A strep manages to outsmart the body’s defenses remains mysterious. To better understand the bacteria’s elusive ways, Gonzalez and his lab have spent the past few years studying the suite of molecules produced by the pathogen during infection. Some of these molecules stick to red blood cells, including a handful of proteins that can rip the cells to shreds.

"But when the researchers used nanoparticles coated with pieces of blood cells as bait, they snared a new protein called S protein. Instead of tearing blood cells apart, this molecule allowed the bacteria to cling to the pieces left behind.

"At first, the seemingly innocuous stickiness of S protein baffled Gonzalez and his team. But they soon realized it might allow the bacteria to pass as the very cells they’d destroyed—the microscopic equivalent of wolves in sheep’s clothing.

"The deception is an unusual tactic, but an effective one, says co-first author Anaamika Campeau, a biochemist in Gonzalez’s lab. To hide any features that might incriminate group A strep as foreign invaders, the microbes plaster themselves with pieces of cells the immune system sees all the time and knows not to attack, she explains. “Once we kind of came to that idea, it all sort of fell into place.”

"The interaction between group A strep and red blood cells was so strong that the bacteria turned bright crimson when plopped into solutions of human blood. Immune cells, flummoxed by the bloody disguise, largely failed to capture and kill the would-be invaders.

"When the researchers generated a mutant strain of the bacteria that couldn’t make S protein, however, it struggled to disguise itself, turning only faintly pink in the presence of blood. The modified pathogens didn’t fool the immune cells, which quickly gobbled up their targets.


"Microbes mimicking host cells isn’t a new biological trick, says Tiara Pérez Morales, a molecular microbiologist at Benedictine University who wasn’t involved in the study. But the new study puts a plot twist on an old story. “They’re putting on a costume and pretending they’re red blood cells,” she says. “I don’t think I can think of anything else like it.”

"The loss of S protein so severely hamstrings the bacteria that the molecule could be an appealing target for new drugs in the future, Sanderson-Smith says. Blocking the protein’s activity during infection would essentially leave the bacteria in the buff, helping immune cells identify and destroy the pathogens."

Comment: S protein is a great tool for Strep on the attack That bacteria can be this inventive supports Shapiro's findings.

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