Abstract
The acute phase response (APR) is the first line of defense of the vertebrate immune system against pathogens. Mounting an immune response is believed to be energetically costly but direct measures of metabolic rate during immune challenges contradict this assumption. The energetic cost of APR for birds is higher than for rodents, suggesting that this response is less expensive for mammals. However, the particularly large increase in metabolic rate after APR activation for a piscivorous bat (Myotis vivesi) suggests that immune response might be unusually costly for bats. Here we quantified the energetic cost and body mass change associated with APR for the nectarivorous Pallas’s long-tongued bat (Glossophaga soricina). Activation of the APR resulted in a short-term decrease in body mass and an increase in resting metabolic rate (RMR) with a total energy cost of only 2% of the total energy expenditure estimated for G. soricina. This increase in RMR was far from the large increase measured for piscivorous bats; rather, it was similar to the highest values reported for birds. Overall, our results suggest that the costs of APR for bats may vary interspecifically. Measurement of the energy cost of vertebrate immune response is limited to a few species and further work is warranted to evaluate its significance for an animal’s energy budget.
Highlights
Mounting an immune response is believed to be energetically costly, requiring trade-offs with other important biological functions (Sheldon & Verhulst, 1996)
The first direct measurements of the energy cost of acute phase response (APR) activation in wild vertebrates were made for birds and were higher than for laboratory rodents suggesting that this response is less expensive for mammals (Marais, Maloney & Gray, 2011)
The large increase in resting metabolic rate (RMR) recently measured for the fish-eating Myotis (Otálora-Ardila et al, 2016; Otálora-Ardila et al, 2017) and the results of our study do not support this idea
Summary
Mounting an immune response is believed to be energetically costly, requiring trade-offs with other important biological functions (Sheldon & Verhulst, 1996). The energy cost of immune response activation by vertebrates, for example, has been hypothesized to equal that of reproduction and growth (Lochmiller & Deerenberg, 2000). The acute phase response (APR), in particular, is believed to be the most energetically costly component of the activation of the immune system, and more prone to trade-off with other energetically expensive life-history traits (Lochmiller & Deerenberg, 2000; Bonneaud et al, 2003; Lee, 2006; but see King & Swanson, 2013). Direct measures of metabolic rate challenge the idea that an immune response is an energetically costly process. RMR of several bird species increased only 5–15% following activation of humoral and cell-mediated immunities (Hasselquist & Nilsson, 2012)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
