Molecular and morphological studies of Brazilian Trypanosoma evansi stocks: The total absence of kDNA in trypanosomes from both laboratory stocks andnaturally infected domestic and wild mammals

The kinetoplast DNA (kDNA) minicircle molecules of 14 Brazilian stocks of T rypanosoma evansi were studied by morphological approaches (Giemsa and 4'-6 '-diamidino-2-phenylindole staining and transmission electron microscopy) a nd molecular approaches (probing with an oligonucleotide complementary to t he minicircle origin of replication and polymerase chain reaction amplifica tion of a minicircle sequence). All methods indicated the absence of both a typical kinetoplast and kDNA minicircles, even in a very small number of p arasites of a single stock or in small numbers of copies of molecules per c ell. We did not detect any altered kDNA molecules. There were no kDNA molec ules in either old or new stocks of T. evansi maintained by successive pass ages in mice. Similarly, no kDNA minicircles were detected in trypanosomes in blood smears from naturally infected domestic and wild animals. Thus, th e total absence of kDNA in Brazilian stocks of T. evansi from both domestic and wild mammals is probably the natural state of Brazilian T. evansi.