The Fetus, the Host, and the Nematode: Interactions between Nematode Infection and Reproduction in Peromyscus mice

Abstract

Infection by nematodes is widespread across the globe, with extreme prevalence in the tropics. While many studies have examined the effects of nematode infection on the immune system, few studies have considered how reproduction complicates, and is complicated, by nematode presence in the gut. Both the fetus and the nematode are identified by the host as genetically diverse organisms and both rely heavily on the host for survival. Nonetheless, the host responds to these organisms with unique motivations- to protect the fetus and to destroy the nematodes. This study sought to understand how the fetus and the nematode directly and indirectly affect the host- directly, by drawing from the host’s own resources and inducing specific immune responses, and indirectly, by affecting the other foreign visitor. Lastly, this study aimed to identify the combined effect of both the fetus and the nematode on the host, specifically by affecting serum protein concentrations. Wild Peromyscus mice of the Peromyscus leucopus and Peromyscus maniculatus species were trapped in the Appalachian Mountains of Mountain Lake Biological Station. Deworming treatments containing Pyrantel and Ivermectin were used to remove nematode infection from approximately half of the mice. Mouse fecal samples were used to quantify nematode egg burdens using microscopy techniques. Retro-orbital bleeds were done to collect small blood samples from each of the mice. These blood samples were analyzed using ELISA assays and Coomassie stains to quantify the albumin and total protein concentrations. The results provided evidence of immunomodulation by nematodes in the gut which was evidenced by decreased globulin and total protein concentrations. While the state of pregnancy mimicked a state of no pregnancy, the effects of lactation mimicked the effects infection. Additionally, this study demonstrated that albumin is largely resistant to change, except in harsh circumstances. Our results demonstrated that the combination of lactation and infection may represent one such harsh circumstance. Our results also suggested an interaction between coccidia and nematodes which may influence pregnancy in the host. We found little effect of host resources on either nematode infection or reproduction. Future research should continue to expand on these findings and understand how parasite dynamics between species may affect the dynamic between reproduction and infection in the host.