The acute phase response elicited by a viral-like molecular pattern increases energy expenditure in Artibeus lituratus

Abstract

Assessments of specific virus-host interactions via experimental infection has shown that bats do not show clinical symptoms of disease, including some hallmarks of acute phase response (APR), upon specific viral infections. Despite these findings, the metabolic cost of APR upon viral challenge has not yet been studied in bats. Therefore, we evaluated the energy cost of APR in Artibeus lituratus upon challenge with polyinosinic-polycytidylic acid (Poly(I:C)), a synthetic analog of double-stranded RNA that induces APR in mammals. To do this, we compared the resting metabolic rates of bats before and after the Poly(I:C) challenge and evaluated skin temperature and body mass loss. Our results revealed that the innate immune response elicited by Poly(I:C) involves a resting metabolic rate increase of 20%, equivalent to 0.28 Kj/h, associated with a body temperature increase of 1.2 °C. In principle, this increase is approximately three times lower than that previously reported in bat species challenged with a bacterial molecular pattern and represents 0.25% of the daily energy expenditure calculated for A. lituratus. The reasons underlying the differing APR energy costs induced by bacterial and viral molecular patterns as well as whether this energy investment, which is trivial in appearance, impacts the daily energy expenditure of A. lituratus remain to be determined.