A dysflagellar mutant of Leishmania (Viannia) braziliensis isolated from a cutaneous leishmaniasis patient

The parasite was cultured in vitro and characterized morphologically using optical and electron microscopy. Identification was performed based on monoclonal antibodies and internal ribosomal spacer typing. In vitro macrophage cultures, murine experimental models and sand fly infections were used to evaluate infectivity in vitro and in vivo.The isolate was identified as Leishmania (Viannia) braziliensis. In the atypical promastigotes grown in culture, a short flagellum surrounded or interrupted by a protuberance of disorganized material was observed. A normal axoneme was present close to the basal body but without elongation much further outside the flagellar pocket. A disorganized swelling at the precocious end of the axoneme coincided with the lack of a paraflagellar rod structure. The isolate was able to infect macrophages in vitro, induce lesions in BALB/c mice and infect Lutzomyia longipalpis.Notwithstanding the lack of an extracellular flagellum, this isolate infects macrophages in vitro and produces lesions when inoculated into mice. Moreover, it is able to colonize phlebotomine sand flies. Considering the importance attributed to the flagellum in the successful infection and survival of Leishmania in the insect midgut and in the invasion of macrophages, these findings may bring new light into the infectious mechanisms of L. (V.) braziliensis.Leishmania spp. are the etiological agents of a group of diseases known as leishmaniasis. The complex clinical presentations vary from localized cutaneous lesions to fatal visceral involvement. Leishmaniasis is endemic in the whole tropical and subtropical world with estimates of 12 million people currently infected. This protozoan parasite undergoes a complex life cycle alternating between the phlebotomine sand fly vector and a mammalian host. The vector is infected by the ingestion of a contaminated bloodmeal containing amastigotes. In the insect midgut, parasites transform into promastigotes, spindle-shaped, highly mot