ITS1 and cpb genetic polymorphisms in Algerian and Tunisian Leishmania infantum isolates from humans and dogs

Leishmania (L.) infantum strains, isolated from varying hosts and clinical manifestations (cutaneous, visceral and canine leishmaniasis), were investigated in order to understand the genetic polymorphisms within this species in Algeria and Tunisia. Two DNA-based typing methods were tested in order to evaluate their effectiveness against Multilocus enzyme electrophoresis (MLEE), widely considered as the reference method for Leishmania parasite typing. On the other hand, MLEE is cumbersome, high-cost, time consuming and frequently does not detect intra-species genetic polymorphisms. In this work, we used two molecular target regions to discriminate L. infantum strains, Internal transcribed spacer 1 (ITS1) and the cysteine proteinase B (cpb). The ITS1 region offers good resolution for Leishmania discrimination but does not spotlight intra-species polymorphisms. In contrast, cpbE and cpbF PCR-Sequencing demonstrated a certain variability within CL and VL Algerian and Tunisian L. infantum isolates. Following phylogenetic analyses of 44 L. infantum isolates, two main groups were identified, a group with 39 bp deletion in the cpb sequence, composed of cutaneous, visceral and canine isolates from both countries with no significant clinical or geographic distribution; these samples were typed as MON-1, MON-24, and MON-80 zymodemes. A second group which presents a clear clusterization of Tunisian cutaneous strains belonging to the L. infantum MON-24. This group, with no deletion in the mature domain of the cpb gene sequence, should be further explored with a higher number of samples.