Immune responsiveness associated with experimental Encephalitozoon intestinalis infection in immunocompetent rats

Microsporidial infections have been recognized as an increasingly important infection in immunocompromized patients, particularly those infected with HIV/AIDS. This study was designed to study immune responses associated with experimental Encephalitozoon intestinalis infection in immunecompetent rats.

Thirty-four rats in 3 groups, A (Control), B (Intraperitoneal) and C (Oral) were given injections of 0.5 ml of 2 x 10(6) of purified spores of Encephalitotozoon intestinalis spores and were observed for serum specific IgG for 21 days using both Direct and Indirect ELISA.

In indirect ELISA, specific lgG were detected on days 7, 14 and 21 for the group B rats and on day 21 for group C and in direct ELISA method, specific lgG were detected in-group B rats on days 7 and 21, for group C rats on day 21 only, while in the control rats, specific lgG were not detected. There was no significant difference between the direct and indirect methods (df=1, X(2), P>0.05). E. intestinalis was observed in stool samples of rats in 1/12 (08.33%) on days 14 and 21 in group B and in 4/10 (33.33%), 3/10 (25.00%) and 2/10 (16.67%) on days 7, 14 and 21 respectively in group C. In-group, A which is the control rats, no microsporidia were observed on days 0, 7, 14 and 21.

There were no changes in the T-lymphocyte counts of rats prior to and after inoculation with spores. Extensive lesions were observed along the intestinal walls especially on the middle and lower sections of group C rats only.