In Algeria, visceral leishmaniasis is caused principally by Leishmania infantum MON-1, a common agent of the disease on the edges of the mediterranean basin. Other zymodemes (MON-34 and MON-80) of the same complex have also been isolated from immunologically competent patients. In the present study, the authors report the presence of Leishmania infantum MON-24, the main agent of cutaneous leishmaniasis in northern Algeria, in five children with visceral leishmaniasis.
Antimonials remain the first-line treatment for the various manifestations of leishmaniasis in most areas where the disease is endemic, and increasing cases of therapeutic failure associated with parasite resistance have been reported. In this study, we assessed the molecular status of 47 clinical isolates of Leishmania causing visceral and cutaneous leishmaniasis from Algeria, Tunisia, and southern France. In total, we examined 14 genes that have been shown to exhibit significant variations in DNA amplification, mRNA levels, or protein expression with respect to resistance to antimonials. The gene status of each clinical isolate was assessed via qPCR and qRT-PCR. We then compared the molecular pattern against the phenotype determined via an in vitro sensitivity test of the clinical isolates against meglumine antimoniate, which is considered the reference technique. Our results demonstrate significant DNA amplification and/or RNA overexpression in 56% of the clinical isolates with the resistant phenotype. All clinical isolates that exhibited significant overexpression of at least 2 genes displayed a resistant phenotype. Among the 14 genes investigated, 10 genes displayed either significant amplification or overexpression in at least 1 clinical isolate; these genes are involved in several metabolic pathways. Moreover, various gene associations were observed depending on the clinical isolates, supporting the multifactorial nature of Leishmania resistance. Molecular resistance features were found in the 3 Leishmania species investigated (Leishmania infantum, Leishmania major, and Leishmania killicki). To our knowledge, this is the first report of the involvement of molecular resistance genes in field isolates of Leishmania major and Leishmania killicki with the resistance phenotype.
Cette etude presente l'identification, pour la premiere fois, de Leishmania infantum zymodeme MON-80 chez 6 chiens provenant d'Algerie et de Tunisie par la methode de migration electrophoretique comparatives des iso-enzymes parasitaires. Ce variant enzymatique ayant deja ete signale chez l'homme lors de leishmanioses viscerales et cutanees en Europe du sud et au Maghreb (Algerie et Tunisie), ces resultats viennent renforcer le role du chien comme reservoir principal du complexe Leishmania infantum.
Iso-enzymatic characterization of 19 Leishmania strains isolated from Tunisian dogs revealed that all correspond to Leishmania infantum MON-1. This confirms the role of dog as a reservoir of the commonest zymodeme responsible for human visceral leishmaniasis in the Mediterranean basin. However, and in spite of the high number of identifications, many zymodemes, mainly the dermotropic ones as Leishmania infantum MON-24, frequently reported in humans, had never been isolated from dogs. The study of their cultural characteristics may contribute to explain the particular iso-enzymatic profile of dogs strains.
