Studies on the Helminth Fauna of Alaska. XXXI. Observations on the Propagation of the Larval Echinococcus multilocularis Leuckart, 1863, In vitro

Abstract

METHODS Each of 4 experiments consisted of the inoculation of a series of culture tubes. The culture medium consisted essentially of 40% human ascitic fluid in Hank's basic salt solution. To this was added 100 units of penicillin and 100/Agm of streptomycin per ml. Phenol red is the indicator in Hank's solution. Some tubes were also inoculated with a malignant human epithelial cell (HeLa strain), which was allowed to become well established before the cestode tissue was introduced. In some cases, extract of vole embryo (Microtus) or human plasma was added. Screw-cap tubes were used routinely, but Leighton tubes were also used in an attempt to follow better the development of individual vesicles. In an effort to immobilize groups of vesicles, perforated cellophane was placed in some of the tubes. The tubes were incubated at 35? C in a horizontal position without rotation. Tissue of larval cestodes was collected aseptically from the livers of experimentally infected rodents. Three species of hosts were utilized: field vole, Microtus pennsylvanicus Ord; red-backed vole, Clethrionomys rutilis Pallas; brown lemming, Lemmus sibiricus Kerr.1 After removal from the host, the larval tissue (in some cases with small quantities of hepatic cells) was finely divided with scissors. The resulting material was introduced by pipette into the culture tubes. The medium was changed on an average of every 3 to 4 days, or whenever this was indicated by a drop in pH. In some instances, the pH was temporarily adjusted by the addition of isotonic sodium bicarbonate, or by the addition of 5% CO2 in air.