Microbes living in the guts and airways of mammals help their hosts to fend off pathogens.
John Wherry and David Artis at the University of Pennsylvania in Philadelphia and their team treated mice with antibiotics to kill off their gut microbes and then infected them with an influenza virus. The mice lost more weight and were more likely to die than those that did not receive antibiotics. The antibiotic-fed mice also mounted a reduced immune response to the virus.
The authors suggest that the bacteria living in mammals prime the immune system to respond to pathogens, and say that harnessing this ability could aid in the treatment of viral infections in humans.
Immunity http://dx.doi.org/10.1016/j.immuni.2012.04.011 (2012)