Abstract:

In this study, PCR was performed to amplify repeated DNA sequence in Leishmania DNA extracted from a sample of Leishmania isolate from dog, a bone marrow sample from an infected dog, 3 bone marrow samples from patients, and two Phlebotomus samples. The amplified products underwent bi-directional sequencing after capillary electrophoresis. The DNAstar SeqMan software was used for sequence assembly, and the sequences were aligned with other DNA repeated sequences reported in literature. Homology was analyzed and phylogenetic trees were constructed using the neighbor joining method. PCR resulted in a product of ~260 bp for all the 7 samples, which was consistent with expectation and verified by sequencing. Results of sequence alignment showed that the products from the 7 samples differed from the reference sequences of L. infantum (GenBank No. L42486) and L. donovani (GenBank No. L42486) in only 1 base. Homology analysis revealed over 90% species homology to the reference sequences, with some samples reaching 100%. The phylogenetic tree showed that the 7 sequences clustered into a branch with L. infantum and L. donovani. Combined with the epidemiological data, these results suggest that the Leishmania species in Shaanxi Province is L. infantum.
  

Key words: Leishmania, repeated DNA sequence, Molecular identification