Coupling between tolerance and resistance for two related Eimeria parasite species

Abstract

Host defense mechanisms evolve to alleviate the detrimental effect of parasites. They can be categorized into two components: resistance and tolerance (Råberg et al., 2009). Resistance is the ability of a host to reduce parasite burden, resulting from defense against parasite infection or proliferation early after infection (Schmid-Hempel, 2013). The negative effect of resistance on parasite fitness can lead to antagonistic coevolution. According to theoretical models, fluctuating host and parasite genotypes arise, and

DNA-based quantification and counting of transmission stages provides different but complementary parasite load estimates: an example from rodent coccidia (Eimeria)

“…To test whether the intensity of Eimeria DNA, oocyst counts or the combination of both are better predictors of host health, we used the maximally measured Eimeria DNA per gram of faeces and maximum OPG in a linear model trying to explain the weight maximally lost by an individual mouse (model A; LRT: χ 2 = 22.44, df = 3, P < 0.001). As expected [ 7 ], we found that both OPG and faecal Eimeria DNA explained maximum weight loss during infection (LRT: OPG: χ 2 = 6.66, df = 2, P = 0.036; genome copies per gram faeces: χ 2 = 18.18, df = 2, P < 0.001). The interaction between the two terms was found to be not significant (LRT: χ 2 = 2.54, df = 1, P = 0.11) (Table 1 ).…”

“…Twenty-two house mice ( M. musculus ) of the “wild-derived” inbred strains SCHUNT, STRA, BUSNA and PWD as well as F1 inter-strain crosses [ 7 , 23 – 25 ] were obtained from the Institute of Vertebrate Biology of the Czech Academy of Science in Studenec (licence: 61974/2017-MZE-17214). The age of the mice at infection ranged from 9 to 19.43 weeks and weight at start of experiments ranged from 15.16 to 28.95 g (Additional file 1 : Table S1).…”

“…Eimeria ferrisi Brandenburg64 (hereafter E64) was isolated from the faeces of a wild M. musculus domesticus mouse captured in Brandenburg, Germany in 2016 and identified by microscopical description and molecular amplification of the 18S ribosomal RNA and cytochrome c oxidase (COI) markers [ 16 ]. E64 oocysts were produced by continuous passage in NMRI mice and sporulated as described previously [ 7 ]. Oocysts of the strain E. falciformis Bayer-Haberkorn [ 26 , 27 ] were used for the generation of DNA standards.…”

“…Asexual stages of many protozoans replicate within the tissues of their host before commitment to sexual stage differentiation and eventual fertilization in the same or different hosts. For monoxenous intracellular parasites like Coccidia, the count of their reproductive stages (oocysts) has been used to measure parasite load, as in the context of estimating host resistance [ 4 – 7 ]. The estimation of tissue load is complex for protozoa, especially with classical histological techniques.…”

“…Disease tolerance does not impact (i.e. reverse, as in E. falciformis infections) the quantitative effect of E. ferrisi on the health of its host, meaning that the amount of oocysts detected during an infection correlates positively with the severity of the impact on host health during the patent period [ 7 ].…”