No, bats “are not virus sacs”. Dominique Pontier insists on breaking the neck of clichés. Researcher, professor at Lyon-1 University, she has been working since 2010 on these small mammals which she has studied in Gabon, Guyana, metropolitan France and even very close to Reunion. Admittedly, bats do not develop any symptoms, unlike humans. They have this amazing ability to resist microbes, but “that doesn’t mean they are calm,” she points out. Quite the contrary. When they are “in a state of torpor” and their body temperature drops to 6°C, their immune system is completely at rest. Viruses can have a field day, except bats are tough types. In the end, they rarely get sick.
Several scientists, including Dominique Pontier and Stéphanie Jacquet, post-doctoral student at the Laboratory of Biometrics and Evolutionary Biology (LBBE) and at the International Center for Research in Infectiology (CIRI), have studied the genome of bats at length to understand where their incredible immunity. The results of their research just published in the review Science Advances.
A body temperature that rises to 41°C in mid-flight
“The bat is the only mammal that flies. And that changes everything,” smiles Dominique Pontier. Moving through the air requires “considerable energy”, fifteen to sixteen times greater than that of a bird. “The effort they provide increases their metabolism considerably. This energy generates toxic oxidative stress, which is very harmful to their cells, but bats have developed a powerful antioxidant system to defend themselves,” she explains. In full flight, their body temperature can rise to 41°C, as if they were seized with a very high fever. “This limits virus replication and helps control inflammation,” continues the researcher.
But this is not the only explanation. Exposed “for millions of years” to viruses of all kinds, sometimes harmful to their survival, bats have been able to “adapt” to resist. They managed to duplicate the PKR gene within their genome, whereas other mammals – including humans – have only one copy of this gene. “To better understand, let’s take the example of a war,” suggests Stéphanie Jacquet. You go into battle, all armed with a sword except that the bats have several, very different from each other. This gives them an advantage because, by developing and diversifying the number of weapons at their disposal, they increase their resistance capacity. »
Indispensable to the ecosystem, bats, great mosquito eaters, definitely never cease to amaze. Recently, another study revealed that they could produce “grunts”, very low frequency sounds using their “false vocal cords”, which only death metal singers manage to activate!