DAO 41:195-201 (2000)  -  doi:10.3354/dao041195

ABSTRACT: An in vitro culture system was developed for Trypanoplasma borreli, a pathogenic flagellate from the blood of European cyprinids. Trypanoplasms multiplied rapidly in a mixture of Hanks¹ balanced salt solution (HBSS, 45%), L15 (22.5%), Earle¹s minimum essential medium (MEM, 22.5%) and 10% distilled water, which was supplemented with 5 to 10% heat-inactivated pooled carp serum. In medium supplemented with fetal bovine serum, multiplication of T. borreli seemed to be inhibited. Cultures initiated with less than 100000 T. borreli per ml culture medium did not survive, and a substantial multiplication of trypanoplasms was found at inocula beginning with 630000 flagellates ml^-1. Trypanoplasms multiplied at 15, 20 and 25°C. In cultures incubated at 4°C the trypanoplasms remained viable but the number of flagellates did not increase. Trypanoplasms from in vitro cultures retained their infectivity for carp for at least 90 d (5 passages). The trypanoplasms survived in culture over a period of up to 5 mo (10 passages). The established culture system allows the propagation of high numbers of fish-infective trypanoplasms, which are required to study parasite-host relationships in carp.

KEY WORDS: Trypanoplasma borreli · Haemoflagellate · In vitro culture