Phenotypic Characterization of the Response to Infection with iTrichinella spiralis/iin Genetically Defined Mouse Lines of the CBi-IGE Stock

摘要

Trichinella spiralis (T. spiralis), which is a cosmopolitan nematode that infects humans among other species, presents a complex host-parasite relationship that hinders the development of tools to eradicate the parasitosis. The aim of this research was to analyze the host response during a primary infection with T. spiralis in five genetically different mouse lines of the CBi-IGE stock. Adult males from the CBi+, CBi−, CBi, CBi/L and CBi/C lines were infected with 1, 2 or 4 L1 larvae per g of body weight. In the chronic stage, the number of parasites per g of tissue (relative larval load, rLL) showed a significant host genotype-dose interaction, since it did not increase in the same way in the five genotypes. At the lowest dose, both CBii−and CBi/L mice were resistant while CBi+, CBi/C, and CBi were susceptible. At the highest dose, only CBi/L remained resistant, and CBi+ was the most susceptible. The reproductive capacity index of adult worms (RCI = rLL/infective dose) evinced only a genotype effect, allowing rating each line as resistant or susceptible regardless of dose. Animals receiving 2 L1 larvae were also sacrificed in the intestinal phase (6 and 13 days p-i) to determine the number of adult parasites (nAP) recovered in a small intestine segment, and female fecundity (Ff). No differences in nAP were observed among genotypes on day 6 p-i. nAP decreased between days 6 and 13 p-i, this reduction being different among genotypes and significant only in CBi/L and CBi/C. Ff decreased in CBi/L and CBi/C on day 13 p-i. At the time of infection, serum cytokine baseline values showed a Th1 orientation for genotype CBi/L (high IFN-γ and IL-2) and a Th2 for CBi+ (high IL-4 and IL-10).The variability in the response observed in this murine model suggests its potential usefulness to gain insight into the mechanisms that regulate host-parasite relationship.