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Giardiasis in mice: studies on the characteristics of chronic infection in C3h/He mice
Abstract:
When C3H/He mice are dosed orally with fecal cysts or trophozoites of the intestinal parasite, Giardia muris, they become chronically infected, whereas BALB/c (or DBA/2) mice rapidly eliminate their infection. The ability to eliminate a primary infection or resist a challenge infection was not related to levels of serum IgA antibody directed against a crude extract of trophozoites. The possibility that the development of host-protective immunity may either be delayed or absent in C3H/He mice was investigated by 2 types of experiment: 1) BALB/c and C3H/He mice were drug-cured at various times after a primary infection and assessed for their ability to resist reinfection, and 2) the ability of infected female mice to protect their suckling young was assessed. Under these experimental conditions, no significant difference in the kinetics of development of resistance to a challenge infection was noted. Thus, mice of both strains were capable of resisting a challenge infection after drug-cured and infected mothers were able to protect their suckling young from a challenge infection. Drug-cured long-term infected mice were resistant to a challenge of either cysts or trophozoites obtained from either 1-wk infected nude mice or long-term infected C2H/He mice. Thus, it is unlikely that the explanation for chronic infection oif C3H/He mice is that variants or a modified population of G. muris trophozoites arise to which C3H/He mice have a defective response. The possibility that G. muris is able to suppress host-protective responses in chronically-infected C3H/He mice but not in BALB/c mice is discussed.
Insights
C3H/He mice develop chronic Giardia muris infections, unlike BALB/c mice. This study found no difference in developing resistance to reinfection between these mouse strains, suggesting Giardia muris may suppress immune responses in chronic infections.
Area of Science:
- Immunology
- Parasitology
- Microbiology
Background:
- Giardia muris infection outcomes vary significantly between mouse strains, with C3H/He mice becoming chronically infected and BALB/c mice rapidly clearing the infection.
- Serum IgA antibody levels against Giardia muris trophozoites did not correlate with the ability to eliminate infection or resist challenge.
Purpose of the Study:
- To investigate the development of host-protective immunity against Giardia muris in C3H/He and BALB/c mice.
- To determine if Giardia muris variants or suppressed host immune responses contribute to chronic infections in C3H/He mice.
Main Methods:
- Assessing the resistance to reinfection in drug-cured C3H/He and BALB/c mice after primary Giardia muris infection.
- Evaluating the ability of infected mothers to protect their suckling young from Giardia muris challenge.
- Challenging drug-cured, long-term infected mice with Giardia muris cysts and trophozoites from different sources.
Main Results:
- Both C3H/He and BALB/c mice demonstrated similar kinetics in developing resistance to Giardia muris challenge infection after drug cure.
- Infected mothers, regardless of mouse strain, could protect their suckling young from Giardia muris challenge.
- Drug-cured mice with long-term infections were resistant to challenge with Giardia muris from various sources, including those causing chronic infection.
Conclusions:
- The development of resistance to Giardia muris challenge is comparable between C3H/He and BALB/c mice.
- It is unlikely that Giardia muris variants or modified trophozoites explain chronic infections in C3H/He mice.
- Giardia muris may suppress host-protective immune responses in chronically infected C3H/He mice, but not in BALB/c mice.