The Problem of Mixing up of Leishmania Isolates in the Laboratory: Suggestion of ITS1 Gene Sequencing for Verification of Species

BACKGROUND: Leishmaniasis is endemic in Iran. Different species of Leishmania (L.) parasites are causative agents of this disease. Correct identification of Leishmania species is important for clinical studies, prevention, and control of the diseases. Mix up of Leishmania isolates is possible in the laboratory, so there is need for verification of species for isolates of uncertain identity. Different methods may be used for this purpose including isoenzyme electrophoresis and molecular methods. The isoenzyme electrophoresis, due to its drawbacks, is feasible only in specialized laboratories while molecular methods may be more feasible. The aim of this research was to study the application of the internal transcribed spacer 1 (ITS1) sequencing method, in comparison to isoenzyme electrophoresis method, for verification of Leishmania species. METHODS: Six Leishmania isolates were received from different research institutions in Iran. The species of these isolates were known by donating institution according to their isoenzyme profile. The species of these isolates were re-identified in Pasteur Institute of Iran by PCR amplification of ITS1 followed by sequencing and comparison of these sequences with Leishmania sequences in GenBank. Isoenzyme electrophoresis was performed for confirmation of the results of ITS1. RESULTS: ITS1 sequence showed that some isolates were mixed up or contaminated with Crithidia. Isoenzyme electrophoresis confirmed the results of ITS1 sequences. CONCLUSION: ITS1 sequencing is relatively more feasible than the traditional isoenzyme electrophoresis method and is suggested for verification of Leishmania species.