Science: Ants clean their peers to protect them from infection
Ants protect themselves from infections by cleaning their peers, which could otherwise pose a danger to the entire colony. But not the cleaning itself shows the disease-preventing effects, but the minimal absorption of the pathogens during the cleaning process, report the professor Sylvia Cremer from the Institute of Science and Technology Austria (IST) in Klosterneuburg and colleagues.
The social contact with sick ants leads to immune protection for the nest inhabitants, the researchers headed by Prof. Sylvia Cremer from the Institute of Science and Technology in the specialist magazine "PLoS Biology". Ants lick their infected counterparts while cleaning and protect themselves from illness by ingesting minimal doses of pathogens, the researchers write. The cleaning process thus acts as a type of vaccination that prevents the spread of infections in the colony.
Collective hygiene behavior protects ants from infections Like in cramped megacities, infections could spread easily in ant colonies if the small animals did not have a "social immune system" to protect them from the diseases, explained Prof. Sylvia Cremer. The collective hygienic behavior of the ants and the associated recording of small amounts of the pathogens form an efficient method to contain infections, the IST researchers continue. If the animals did not protect themselves from diseases in this way, infections could easily spread in the densely populated ant building and, at worst, could mean the end of the entire colony. By licking off their peers during the cleaning process, the animals are literally vaccinated. The sick animals are not avoided, but licked by their peers "to remove the pathogen from the body of the ants affected", the researchers report to Prof. This "social care behavior" would significantly increase the chances of survival of the infected individuals. But cleaning the sick conspecifics also has advantages for the caring ants, according to the IST researchers.
Risk of infection reduced by cleaning sick companions While caring ants are exposed to an increased risk of infection due to contact with the sick animals, they only consume doses of the pathogen so small that "only sublethal infections" occur, report Prof. Cremer and colleagues in the Article "Social Transfer of Pathogenic Fungus Promotes Active Immunization in Ant Colonies". The scientists had observed the spread of fungal spores in an ant colony and found that there was only a very small "transfer of spores" during the cleaning process. The ingestion of low doses of the infectious spores activated the immune system in the healthy animals and from then on they were protected from disease, according to Cremer and colleagues. In this way, the spread of infections is successfully prevented. Only two percent of the newly infected ants died after contact with the spores of the fungus metarhitic, the remaining animals were immune, the IST researchers explained. Ants' protection against infection works similarly to vaccinations in humans. The "social spread of infectious particles at a low level" offers a kind of "social immunization against fungal diseases in ant colonies", the scientists conclude.
Social immunization as disease protection in humans? A comparable social immunization could also be effective in humans, Simon Babyan from the University of Edinburgh and David Schneider from Stanford write in an accompanying article in the specialist magazine "PLoS Biology". "By studying social immunity in colonies of insects, we may be able to discover emergent traits that we have previously overlooked in another important social animal, humans," Babyan and Schneider emphasize. According to the two commentators, the IST researchers used “a combination of methods to identify the mechanism of social immunization: mathematical models, behavioral, microbiological, immunological and molecular techniques, all of which offer an exciting proof-of-concept that Immunity at group level can be experimentally manipulated and modeled. "(Fp)
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