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Susceptibility dynamics in neonatal BALB/c mice infected with Cryptosporidium parvum
1Department of Veterinary Science, University of Arizona, Tucson 85721.
Abstract:
BALB/c Mice were infected as neonates and at different ages to study the susceptibility dynamics in this animal model to Cryptosporidium parvum. When 4-day-old animals were infected with 10(5) C. parvum oocysts, parasites were detected in the terminal ileum when the mice became 14-25 days old (10-21 days post-infection [PI]). The percentage of animals positive for parasites was 100% up to the age of 19 days (15 days PI) but decreased immediately thereafter until no parasites were detected in 26-day-old (22 days PI) or older mice. Parasite load also decreased in these animals from 184.7 parasites per high power field in 14-day-old animals (10 days PI) to 0.22 in 25-day-old (21 days PI) mice. In a second study, some neonatal mice became resistant to C. parvum when infection was attempted at day-10 of age (day-15 of age at sacrifice). The susceptibility to C. parvum decreased until 14 days of age (19 days of age at sacrifice) when mice could no longer be infected. Parasite load also decreased in infected mice from 235.6 parasites per high power field (9 days of age at sacrifice) to 0.25 (18 days of age at sacrifice).
Insights
BALB/c mice susceptibility to Cryptosporidium parvum infection decreases significantly with age. Neonatal mice are highly susceptible, but resistance develops by 14 days of age, with parasite loads diminishing rapidly.
Area of Science:
- Immunology
- Parasitology
- Animal Models
Background:
- Cryptosporidium parvum is a significant enteric pathogen.
- Understanding host susceptibility is crucial for disease control.
Purpose of the Study:
- To investigate the age-dependent susceptibility of BALB/c mice to Cryptosporidium parvum infection.
- To characterize the dynamics of parasite load and infection prevalence in relation to host age.
Main Methods:
- BALB/c mice were infected with Cryptosporidium parvum oocysts at various ages, from neonates to older animals.
- Infection status and parasite loads were assessed at different time points post-infection.
- Age-related changes in susceptibility and parasite burden were analyzed.
Main Results:
- Neonatal mice (up to 19 days old) showed 100% susceptibility to C. parvum.
- Susceptibility and parasite load decreased sharply in mice older than 19 days.
- Resistance to infection was observed by 14 days of age, with minimal parasite detection in older mice.
Conclusions:
- BALB/c mice develop resistance to Cryptosporidium parvum infection as they mature.
- Age is a critical factor influencing the outcome of C. parvum infection in this animal model.
- This study provides insights into the developmental immunology of cryptosporidiosis.