// UC Riverside; ktsdesign / Depositphotos
When we talk about cholera, most think of contaminated water and tragic outbreaks in vulnerable regions, but behind the scenes, the bacteria of cholera are involved in a microscopic war that can shape the pandemic course.
We had the news for days that, according to WHO, in Africa, with more than 157 thousand cases and 2,148 deaths between January and April.
But what explains the resilience of this disease, which insists on devastating the African continent, year after year?
According to a new study, conducted by EPFL researchers, It has a secret: it is smarter than viruses.
The bacteria of cholera are not just fighting against antibiotics and the measures of public healththey are also constantly to be attacked by bacteriophages (faros), viruses that infect and kill bacteria.
These viruses not only influence individual infections, can create or destroy epidemics whole. It is thought that certain bacteriophages limit the size and duration of cholera outbreaks, killing Vibrio choleraethe bacteria responsible for the disease.
The current anger pandemic, the seventh since the 1960s, has been driven by the V. cholerae known as “seventh pandemia the tor”(7pet), which spread around the world.
In this authentic evolutionary race, bacteria adapted to develop mechanisms of defense against these phagos – For example, many bacterial strains carry mobile genetic elements that equip them with tools anti-viral.
So why are certain variants of cholera so successful to escape the attacks of the phagos? Does this allow or increase the devastating effect of the pathogenic agent on human populations?
There is a fact that stands out: at the beginning of 90’san outbreak of cholera in Peru and much of Latin America infected More than 1 million people and caused thousands of deaths.
The responsible strains belonged to the South American line of West Africa (WASA) V. cholerae. The reason these Wasa variants have caused such a large outbreak in Latin America is not yet fully understood.
A new study, conducted by Melanie Blokeschresearcher at the EPFL Global Health Institute, has now discovered a Secret behind these variants.
O, published last week in the magazine Nature Microbiologyshows that the WASA lineage acquired multiple distinct bacterial immune systems that protected it from various types of phagos, and this defense may have contributed to the Disease proliferation.
The researchers analyzed the variants of Peruvian cholera of the 1990s, through testing to their resistance against key phagos, especially the ICP1-dominant viruses that has been the focus of study in Bangladesh’s endemic area, which sees in Fago a way to restrict cholera outbreaks.
Surprisingly, the Peruvian variants were immune to ICP1.
A better immune system
When deleting specific sections of the DNA of the cholera variant and by inserting these genes in other bacterial variants to test, the team identified two large Defense regions in the genome of the Wasa variantnamely inside the so -called Profago Play-1 and in the skeleton of the genre of the II (VSP-II).
Is GENOYIC REGIONS They encode specialized anti-Fag systems that work together to create a bacterial immune system capable of defending themselves against phagos infections.
One of these systems, the WonABtriggers an answer from “abortive infection”That kills infected cells before phagos can be reproduced, sacrificing some bacteria to save the majority of the population.
This strategy is different from classical bacterial immune systems, such as restriction modification systems that erase phago DNA as it enters cells.
David Adamsthe first author of the study, says that “instead, it prevents the phage from replicating, but only after already kidnapped the cellular machinery of the cholera bacteria, effectively blocking the bacteria infected in a impasse – but,, At least, Fago does not propagate”.
According to, two other systems, Grwab e VcSduAcontribute to different protection functions.
GRWAB targets phagos with chemically modified DNA, a strategy used by phagos to camouflage their genomes and escape other bacterial immune systems.
To you, on the other hand, Acts against different virus familiesincluding another “VibriophagusCommon, offering layers protection that widens the spectrum of resistance.
Essentially, the WASA lineage of the cholera bacteria houses an extended arsenal of anti-fan defense systems, which allows it neutralize A wide range of bacteriophages, in addition to protection against its main predator phagus, the ICP1.
Understanding how bacteria resist phagos is crucialespecially since the interest in phagos therapy has resurfaced as an alternative to antibiotic treatment.
If bacteria like the V. cholerae They can acquire greater transmission potential by obtaining viral defenses, this can reformulate the way we approach control, monitoring and treatment of cholera.
