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Strain-dependent differences in murine susceptibility to coccidia
Abstract:
Differences in susceptibility of strains of mice to Eimeria ferrisi were observed by infecting eight strains of mice with six infectious dose levels and comparing the mortality rate among the strains for a period of 12 days. Mice of the C57BL/6 and HA/ICR strains were susceptible, and those of A/He, AKR, BALB/c, CBA, C3H/Anf, and DBA/2 strains were resistant to coccidial infection. Resistance was a dominant genetic expression, as indicated by the resistant response of F(1) hybrids of susceptible C57BL/6 and resistant CBA, C3H/Anf, or DBA/2 strains. An E. ferrisi infection in congenitally athymic nu/nu mice and phenotypically normal heterozygous nu/+ mice was used to determine how thymus-dependent immunoincompetence in cell-mediated immunity of the nu/nu mouse affected resistance to infection in a genetic background of the resistant BALB/c mouse. Results of primary and challenge infections in these two strains of mice suggested that resistance is thymus dependent. Furthermore, impairment of thymus-dependent cell-mediated immunity in resistant AKR mice by treatment with mouse antithymus serum led to partial susceptibility. However, susceptible C57BL/6 and HA/ICR strains are phenotypically normal mice, and previous evidence showed that C57BL/6 mice are not completely immunoincompetent in cell-mediated reactivity to coccidia. Collectively, our data show that cell-mediated immunity is necessary for resistance but may be subjected to modification by genetic expression of the host. The possible role of immune response genes in the control of coccidial immunity is discussed.
Insights
Mouse strain differences reveal that resistance to Eimeria ferrisi infection is primarily thymus-dependent and genetically controlled. Cell-mediated immunity is crucial for this resistance, though host genetics can modify its effectiveness.
Area of Science:
- Immunology
- Genetics
- Parasitology
Background:
- Eimeria ferrisi infection susceptibility varies significantly among different mouse strains.
- Understanding the genetic and immunological basis of this variation is key to controlling coccidial infections.
Purpose of the Study:
- To investigate the genetic control and immunological mechanisms underlying differential susceptibility of mouse strains to Eimeria ferrisi.
- To determine the role of thymus-dependent cell-mediated immunity in resistance to Eimeria ferrisi.
Main Methods:
- Infection of eight mouse strains with six infectious doses of Eimeria ferrisi, monitoring mortality for 12 days.
- Genetic crosses (F(1) hybrids) between susceptible and resistant strains to assess dominance of resistance.
- Infection of athymic (nu/nu) and heterozygous (nu/+) mice on a resistant BALB/c background to evaluate thymus dependence.
- Pharmacological impairment of cell-mediated immunity in resistant AKR mice using antithymus serum.
Main Results:
- C57BL/6 and HA/ICR mice were susceptible; A/He, AKR, BALB/c, CBA, C3H/Anf, and DBA/2 mice were resistant.
- Resistance to Eimeria ferrisi infection was found to be a dominant genetic trait.
- Resistance was demonstrated to be thymus-dependent, as athymic mice showed reduced resistance.
- Impairment of cell-mediated immunity in resistant AKR mice led to partial susceptibility, while susceptible strains maintained some cell-mediated reactivity.
Conclusions:
- Cell-mediated immunity is essential for host resistance against Eimeria ferrisi infection.
- Genetic factors significantly influence the host's immune response and susceptibility to coccidiosis.
- Further research into immune response genes controlling coccidial immunity is warranted.