Immunological aspects ofGiardia murisandSpironucleus murisinfections in inbred and outbred strains of laboratory mice: a comparative study

Abstract

SUMMARYThe intestinal flagellates,Giardia murisandSpironucleus muris, cause similar infections in CBA mice as determined by trophozoite and cyst counts. Both parasites occur all along the small intestine withG. muris, being mainly present in the anterior part andS. muristowards the posterior. The early stages of infection are similar in all strains of mice examined and peak levels of both trophozoites and cysts occur 1–2 weeks after infection. All strains of mice overcome the infection but the rate of recovery varies considerably between strains, being most rapid in BALB/c and slowest in A and C57BL.B10. Outbred mice are more variable in their recovery than inbred mice. After recovery, mice are partially resistant to reinfection with the homologous but not the heterologous parasite. Resistance to reinfection withS. murisis greatest in those strains that eliminate the primary infection most rapidly.Giardia murisandS. muriscause similar changes in the mucosa of the small intestine of BALB/c mice with increased intra-epithelial lymphocyte counts from 3 weeks onwards corresponding with the start of the elimination of the parasites from the gut. A reduction in villus height and increase in crypt depth is also characteristic of these infections.