Complete conservation of an immunogenic gene (lcr1) in Leishmania infantum and Leishmania chagasi isolated from Iran, Spain and Brazil.

BACKGROUND & OBJECTIVES: Kala-azar is the visceral and most severe form of leishmaniasis that leads to death if untreated. The causative agents of visceral leishmaniasis (VL) are members of Leishmania (L.) donovani complex which includes L. chagasi and L. infantum. Genome sequences have raised the question whether L. chagasi and L. infantum are synonymous or different. This question has important implications for clinical and epidemiological studies, evaluation of vaccines and drugs, and disease control. LCR1 is an immunogenic molecule discovered from L. chagasi with potential as a component of a Leishmania subunit vaccine. If this protein has potentials for being used in a vaccine or diagnostic testing, there should be little variability in this molecule between L. infantum isolates from diverse geographic regions. The aim of this study was to determine whether lcr1 of an Iranian strain of L. infantum was identical to lcr1 of both L. infantum strain from a different geographic region (Spain) and that of an L. chagasi isolate from Brazil. METHODS: L. infantum isolated from an Iranian kala-azar patient was studied. Lcr1 from this isolate was PCR amplified, cloned, and studied by restriction digest analysis and sequencing. RESULTS: The sequences of lcr1 of the Iranian L. infantum were completely identical at nucleotide level to lcr1 sequences of both the Spanish L. infantum and the Brazilian L. chagasi strains. CONCLUSION: Complete conservation of the DNA sequence encoding for LCR1 molecule between geographically distinct Leishmania species adds credibility to the potential for LCR1 as a component of a subunit vaccine and diagnostic test for kala-azar.