DISACCHARIDASE ACTIVITY IN MALE AND FEMALE C57BL 6 MICE INFECTED WITHGIARDIA-MURIS/

To elucidate the contribution of host and parasite factors in inductio n of small-intestinal disaccharidase deficiency in giardiasis, we dete rmined the activity of four enzymes in male and female C57BL/6 mice in fected with Giardia muris. Both male and female mice exhibited signifi cant disaccharidase deficiency as shown by decreases in the activities of lactase, sucrase, trehalase and maltase on day 10 after infection. However, by 20 days after infection the females had normal enzyme act ivities, whereas those in males remained significantly reduced. prolon ged disaccharidase deficiency in the males was related to the course o f the primary infection where males had higher parasite loads in the s mall intestine than did females on day 20 after infection. By day 40 a fter the primary infection the enzyme activities had returned to norma l levels and were similar in male and female mice. Secondary exposure of mice to either the infective cysts or a crude extract of the tropho zoites caused disaccharidase deficiency. The females had lower activit ies of sucrase and trehalase as compared with males after the challeng e. Thus, during the primary infection, disaccharidase deficiency was s trongly associated with parasite number, whereas after challenge infec tions the more resistant females had lower enzyme activities in the sm all intestine than did males.