Are adventurous mice more prone to viruses?

Date: 8 November 2017

Introduction: In his new research, Bram Vanden Broecke (UAntwerp) investigated whether mice personality affects the animals' chances to be infected by arenaviruses.

Exploration is an important behaviour that helps animals (and humans) to figure out what’s going on in their environment. Exploration provides information on e.g. food availability and the presence of potential mating partners… but it also comes with potential costs. Explorative animals for example have an increased risk for parasite and virus infection.

Recently, researchers have shown that not all animals live a risky life: some individuals are consistently more inclined to explore than others. Such differences in behaviour are often called “animal personality” and are encountered among a wide variety of animals, from humans to insects. In a new study, Bram Vanden Broecke (Global Change Ecology Centre, Research Group Evolutionary Ecology) investigated the link between animal personality and virus infection in the natal multimammate mice (Mastomys natalensis), a typical host for arenaviruses (which can cause serious health problems in humans also).

The natal multimammate mouse
The natal multimammate mouse

Bram explains: “We quantified the exploration behaviour of 122 individuals and found that there were indeed consistent differences between individuals. To quantify how “adventurous” the mice were, they were released in special arenas. After they entered the arena, we tracked their movement for 5 minutes. Subsequently, we introduced a new object, a blue box, in the arena. By careful observation, we could both quantify how individuals differed in their initial arena exploration, and the reaction to the new object. This gave a good idea of their ‘personality’.”

After quantifying the mice’s personality, Bram and his co-authors linked the personality to the degree of infection with arenaviruses. However, a bit to their surprise, infected individuals were not more explorative than healthy ones. This suggests that, at least for the multimammate mice, exploration does not increase the risk to become infected. This left Bram with a new question to explore: which behaviour can cause the observed variability in virus infection. A question he is now actively exploring. Bram: “We clearly observed that mice have different personalities, which is interesting in itself. However, which unknown aspect of personality potentially causes the risk for arenavirus infection, remains unknown. If we can identify it, this will improve also our ability to reduce virus cross-over from mice to humans, since we can then adapt management plans to this new knowledge.”

The results were published in Current Zoology.

​The mice were observed carefully in arenas specifically designed to investigate exploration activity.