Establishment of a C57BL/6N mouse model of giardiasis

Objective To establish a C57BL/6N mouse model infected with Giardia lamblia (G. lamblia) isolates from human origin. Method Two groups of C57BL/6N mouse were inoculated with purified cysts of two G. lamblia isolates (CD and XZ) by gavage separately. Patterns and curves of cyst excretion of the infected mice were observed and summarized. Histopathological changes of the small intestines of the infected mice were observed. Results Thirty- six mice receiving 1×10(4) cysts each were all infected. The C57BL/6N mouse showed high susceptibility to G. lamblia infection. There was no notable distinction between the two groups of the mice infected by the cysts of CD and XZ isolates. Cyst excretion occurred with intermittence. Of 36 infected mice, 32 (89%) passed cysts intermittently and 4 (11%) others persistently. The latent period of cyst excretion was 0-3 days p. i. (post- inoculation). The interruption of cyst excretion ranged from 12 to 20 days p. i. The fastigium of the cyst excretion was on day 6 p. i. The peak count of the cysts passed during a 2 h collection period was 2. 3×107 /g fecal specimen. Edema, inflammation, cell infiltration, small blood vessels congestion, mitotic figures and mucosa necrosis appeared in sections of intestines. Conclusion C57Bl/6N mouse is a suitable animal model of G. lamblia.