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

Abstract

The intestinal flagellates, Giardia muris and Spironucleus muris, cause similar infections in CBA mice as determined by trophozoite and cyst counts. Both parasites occur all along the small intestine with G. muris, being mainly present in the anterior part and S. muris towards 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 with S. muris is greatest in those strains that eliminate the primary infection most rapidly. Giardia muris and S. muris cause 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.

Immune Response to Giardia duodenalis

“…Villus atrophy and crypt hyperplasia were observed in the duodenum of gerbils infected with G. duodenalis trophozoites (22) and mice infected with G. muris (30). Crypt mitotic rates have been reported to double during the acute phase of Giardia infections in mice (115).…”

Immune Response toGiardia duodenalis

“…CD4 ϩ T cells during the elimination phase concomitant with an increase in the number of lamina propria IgA-plasma cells results in the elimination of the parasite from the gut. Villus atrophy and crypt hyperplasia were observed in the duodenum of gerbils infected with G. duodenalis trophozoites (22) and mice infected with G. muris (30). Crypt mitotic rates have been reported to double during the acute phase of Giardia infections in mice (115).…”

Protozoan parasites of British small rodents

“…Transmission is by cysts. Giardia muris is also a parasite of laboratory rodents and has been intensively studied in mice (Brett & Cox, 1982). In laboratory mice it may cause diarrhoea and wasting but its importance in the wild is not known.…”

“…Spironucleus muris, formerly Hexamita muris, is common in the small intestine and caecum of wild rodents and also laboratory mice (Brett & Cox, 1982), in which it may cause diarrhoea, but it is not known if it is pathogenic in the wild. Transmission is by cysts.…”