Studies on the Development of Metacyclic Trypanosoma brucei sspp. Cultivated at 27°C with Insect Cell Lines1

When transformed procyclic trypanosomes of three stocks of Trypanosoma brucei brucei and one stock of T. b. rhodesiense were grown at 27°C in 25-cm² flasks containing Anopheles gambiae cells, some of them developed into forms infective for mice. Infectivity titrations on trypanosome suspensions revealed that up to 2.8 × 10⁵ metacyclic forms per ml could be produced, and the cultures remained infective for varying periods of up to 72 days when they were terminated. Of the various culture media tested, a mixture of three volumes of trypanosome medium and one volume of Anopheles medium was the most successful. Control cultures of trypanosomes grown in medium without cells were generally not infective, but two of the stocks gave rise to a few sporadic infections. Trypanosome populations could be subpassaged in the Anopheles cell cultures without loss of infectivity. Metacyclic forms separated from infective cultures by DEAE-cellulose columns had a surface coat.