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 3×10 7 /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
OBJECTIVE: To investigate the intraspecific difference of the triose phosphate isomerase (tim) gene from Giardia lamblia (G. lamblia). METHODS: Total genomic DNA of G. lamblia was extracted and partial fragments of the triose phosphate isomerase (tim) gene were amplified by polymerase chain reaction (PCR). All nucleotide sequences were analyzed by using a phylogenetic analysis, which was constructed with parsimony and Neighbor-joining (N-J) methods. RESULTS: A total of 124 variable sites (23% of all sequences detected) was defined, most of which were found at the silent sites of codons. Two similar phylogenetic trees were constructed, subdividing 16 Giardia isolates into two groups. CONCLUSION: The genetic diversity of G. lamblia appeared to be little affected by factors of both host and geography, while natural-selection played an important role in DNA molecular evolution level of the tim gene. The tim gene may be considered a very useful genetic marker of the population genetic structure of G. lamblia.
