Long-term calorie restriction does not predict susceptibility of laboratory mice (Mus musculus) to a secondary infection by the parasitic nematode Heligmosomoides bakeri

Parasitic gastrointestinal nematodes cause long-term infections in people and these types of infections can be modeled using laboratory mice (Mus musculus). A benefit oflong-term calorie restriction (CR) of mice is enhanced immune responses that should presumably protect individuals against pathogen infection. It is unknown if long-term calorie restriction will prevent infection with an intact macroparasite, such as the intestinal helminth Heligmosomoides bakeri. H bakeri is a model for human hookworm infection, a common human pathogen worldwide. I studied if long-term calorie restriction would change host susceptibility to a secondary H bakeri infection. Two dietary groups of C57BL/6 mice were used One group was fed ad libitum (AL) while the second group was given CR and were fed at 40% less than ad libitum intake. Mice were fed their designated diets for 303 days, thereafter, they received a primary infection of 125 H bakeri larvae. This first infection was cleared with an anti-helminth (pyrantel pamoate, 175 mg/kg body mass) and then a secondary infection of300 larvae was given 30 days later. Sixteen days post-secondary infection mice were euthanized, Long-term CR yielded the predicted increase in the ability of the immune system to respond, but th1s increased immune response after CR was not sufficient to reduce infection intensity or to affect worm growth and reproduction. AL mice were 104% larger in body mass and had a digestibility that was 2% greater than.CR mice. Keywords: calorie restriction, secondary infection, intestinal parasite, Heligmosomoides bakeri, parasite-host interaction, susceptibility, Mus musculus