Establishment of an axenic culture of Giardia lamblia through preliminary passage in suckling gerbil.

Cysts of Giardia lamblia from fresh stool specimens of a 13-year-old boy, who lived in suburban Beijing and had suffered from recurrent diarrheas for years, were concentrated, purified and suspended in physiological saline. Six suckling gerbils (Meriones unguiculatus) were each inoculated with 0.2 ml of this suspension which contained 20,000 cysts/ml. On day 8 after inoculation, the infected animals were sacrificed and trophozoites of G. lamblia which appeared numerous in the upper small intestines were isolated aseptically. The trophozoites were inoculated into modified TYI-S-33 medium and cultivated at 37 C. On day 14 of cultivation, the organism grew luxuriantly and formed a cellular monolayer on the inner wall of the culture tube. The organism replicated every 15 +/- 2 hours and the peak growth occurred 120 hours after seeding. No bacterial growth was detected by repeatedly transferring the culture onto blood agar plates and into beef broths. Several lots of the culture have been subjected to cryopreservation in liquid nitrogen and the viability of the thawed organism ranged from 50% to 80% 1-10 weeks after being cryopreserved. The thawed parasites grew well in subcultures. This axenic culture has been maintained for one year and 4 months, and more than 150 subcultures have been made.