The molecular characterization of clinical isolates from Indian Kala-azar patients by MLEE and RAPD-PCR.
BACKGROUND
Kala-azar is a serious health problem in India. The situation has worsened further due to the occurrence of cases unresponsive to antimonials. About 30-50% patients do not respond to the prevailing regimen of antimonials. The etiological agent for Indian kala-azar has long been known to be Leishmania donovani. Recently, in a somewhat startling report, it was claimed that L. Tropica causes nearly 25% of current kala-azar cases in India. It was also suggested that this might be in some way related to the unresponsiveness to pentavalent antimonials in the field.


METHODS
Two independent molecular characterization techniques, multilocus enzyme electrophoresis (MLEE) and RAPD-PCR, were employed to analyze 15 clinical isolates from confirmed Indian kala-azar patients collected from the eastern part of the country over a period of nearly 20 years. The collection included six Sb5+-unresponsive and one PKDL case.


RESULTS
Our observations strongly suggest that all the clinical isolates, including the antimony Sb5+-unresponsive and PKDL ones, we studied were identical to the WHO reference strain (DD8) for Leishmania donovani by both the above methods and no strain variation might have occurred in two major epidemic and inter-epidemic periods. We also observed that none of the Sb5+-unresponsive stains we analyzed was related to L. Tropica.


CONCLUSIONS
We conclude that L. Donovani may be the causal agent for Indian kala-azar and that L. Tropica is most likely not an etiological agent for Indian Kala-azar cases that are unresponsive to antimonials.
Leishmania Division, Indian Institute of Chemical Biology, Jadavpur, Kolkata, India. drmanna@vsnl.net
Madhumita
M
Manna
Hemanta Kumar
HK
Majumder
Shyam
S
Sundar
Amar Nath
AN
Bhaduri
D000818:Animals; D001853:Bone Marrow / Q000469:parasitology; D017931:DNA Primers; D004351:Drug Resistance; D004588:Electrophoresis, Cellulose Acetate; D006801:Humans; D007194:India; D007527:Isoenzymes / Q000235:genetics; D007893:Leishmania donovani / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D007895:Leishmania tropica / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D007898:Leishmaniasis, Visceral / Q000175:diagnosis / Q000235:genetics* / Q000469:parasitology; D019105:Random Amplified Polymorphic DNA Technique; D013154:Spleen / Q000469:parasitology
D017931:DNA Primers; D007527:Isoenzymes