ORIGINAL PAPER Comparative transcript expression analysis of miltefosine-sensitive and miltefosine-resistant Leishmania donovani Arpita Kulshrestha & Vanila Sharma & Ruchi Singh & Poonam Salotra Received: 17 October 2013 /Accepted: 3 January 2014 /Published online: 22 January 2014 # Springer-Verlag Berlin Heidelberg 2014 Abstract Leishmania donovani is the causative agent of anthroponotic visceral leishmaniasis in the Indian subconti- nent. Oral miltefosine therapy has recently replaced antimo- nials in endemic areas. However, the drug is at risk of emer- gence of resistance due to unrestricted use, and, already, there are indications towards decline in treatment efficacy. Hence, understanding the mechanism of miltefosine resistance in the parasite is crucial. We employed genomic microarray analysis to compare the gene expression patterns of miltefosine- resistant and miltefosine-sensitive L. donovani . Three hundred eleven genes, representing ∼3.9 % of the total Leishmania genome, belonging to various functional categories including metabolic pathways, transporters, and cellular components, were differentially expressed in miltefosine-resistant parasite. Results in the present study highlighted the probable mecha- nisms by which the parasite sustains miltefosine pressure including (1) compromised DNA replication/repair mecha- nism, (2) reduced protein synthesis and degradation, (3) al- tered energy utilization via increased lipid degradation, (4) increased ABC 1-mediated drug efflux, and (5) increased antioxidant defense mechanism via elevated trypanothione metabolism. The study provided the comprehensive insight into the underlying mechanism of miltefosine resistance in L. donovani that may be useful to design strategies to increase lifespan of this important oral antileishmanial drug. Introduction Leishmania donovani is the etiological agent of visceral leish- maniasis (VL), a potentially fatal systemic protozoal infection. The emergence and spread of resistance to therapy for VL is of significance particularly in India where more than 60 % of patients do not respond to the traditional antimonial therapy. Miltefosine (hexadecylphosphocholine) is an oral drug initially developed as an anticancer agent for the treatment of cutaneous lymphomas and breast cancer that shows selec- tive activity against Leishmania (Clive et al. 1999; Croft et al. 2006). In India, miltefosine has recently taken over as the first- line therapy for VL even in areas where antimonials are effective (WHO TDR News 2004). However, widespread use of miltefosine monotherapy might lead to the rapid emer- gence of resistance in India, where VL is anthroponotic (Bryceson 2001). The long half-life of the drug may poten- tially increase the risk of development of experimental resis- tance to this drug shown to be readily induced in vitro (Seifert et al. 2003). Concerns have been raised over rise in miltefosine treatment failure and relapses (almost double) in phase IV clinical trials in India (Sundar et al. 1998; Sundar and Murray 2005). Already, reports of clinical failure and relapse have come up in India and Nepal (Sundar et al. 2006; Pandey et al. 2009). In this situation, it becomes important to under- stand the mechanism of action and development of resistance towards miltefosine in the parasite. The mechanisms and related biological pathways that con- tribute to miltefosine resistance in the parasite are relatively poorly understood. Suggested targets of miltefosine in Leishmania include perturbation of ether-lipid metabolism, glycosyl phosphatidylinositol anchor biosynthesis, signal Electronic supplementary material The online version of this article (doi:10.1007/s00436-014-3755-6) contains supplementary material, which is available to authorized users. A. Kulshrestha : V. Sharma : R. Singh : P. Salotra (*) National Institute of Pathology (ICMR), Safdarjung Hospital Campus, New Delhi 110029, India e-mail: salotra@vsnl.com Present Address: A. Kulshrestha Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA Parasitol Res (2014) 113:1171–1184 DOI 10.1007/s00436-014-3755-6