ABSTRACT
We examined the basic conditions for cryopreservation of newborn and muscle-stage larvae of Trichinella nativa. Two types of cryoprotectants were examined: dimethyl sulfoxide and glycerol. For cryopreservation of newborn larvae, dimethyl sulfoxide had a cryoprotective effect, and a maximum survival of 96% was obtained under conditions of 10% dimethyl sulfoxide and 30 min equilibration. Muscle-stage larvae, on the other hand, demonstrated a relatively high survival rate (approximately 80%) with 25% glycerol and three hours equilibration regardless of freezing rate. The infectivity of cryopreserved newborn and muscle-stage larvae was examined using different infection methods: direct injection into the abdominal cavity in the former, and either oral infection or direct injection into the duodenum in the later. Cryopreserved newborn larvae showed infectivity to all the subjected mice. By contrast, muscle-stage larvae did not show any infection when infected orally, but one mouse was positive when the larvae were injected directly into the duodenum.