Dados do Trabalho

Título

Isolation and infectivity of Leishmania (Leishmania) infantum clinical isolates from atypical cutaneous leishmaniasis cases

Introdução

Leishmania (L.) infantum (syn. L. chagasi) is the main causative agent of visceral leishmaniasis in the Americas. The symptomatic infections caused by this species are systemic and progressively affect lymphoid organs, leading to death if left untreated. Less often, L. (L.) infantum can also exhibit a dermotropic profile, causing ulcerated or non-ulcerated cutaneous lesions. In Brazil, cutaneous leishmaniasis (CL) caused by this species is usually rare. The mechanisms involved in skin infection by L. (L.) infantum are still unclear and require further investigation.

Objetivo (s)

We describe the isolation, molecular typing and in vitro infectivity of two L. (L.) infantum isolates from cutaneous leishmaniasis cases.

Material e Métodos

Tissue sample of skin biopsies from CL patients were used for parasite isolation. The clinical isolates obtained were typed by PCR and by sequencing of the internal transcribed spacer (ITS) region. The growth curve of each isolate was determined daily by counting in a haemocytometer and the frequency of metacyclic promastigotes was evaluated by flow cytometry. The infectivity of isolates was evaluated in vitro in bone marrow-derived macrophage from mice and THP-1 derived macrophages. As internal control, we used a L. (L.) infantum laboratory strain (MHOM/BR/1972/LD).

Resultados e Conclusão

Two clinical isolates (coded BG03 and BG05) were obtained from CL patients from Maranhão state, Northeast Brazil. PCR and ITS-nucleotide sequence analysis confirmed the isolates to be L. (L.) infantum. Growth curves were similar for 1972, BG03 and BG05, with early stationary-phase at the fourth day of culture. Metacyclogenesis analysis revealed different patterns for the isolates. The frequency of metacyclic forms of BG03 increased slightly from fourth to sixth day of culture, while BG05 showed higher frequency of metacyclics on the fourth day,
drastically decreasing on the sixth day. In vitro infection indicated that promastigotes from the clinical isolates were more infective than the laboratory reference strain on the fourth day of culture in the two macrophage-models used. The macrophage response to infection by each isolate will be analyzed in terms of gene expression of anti- and pro-inflammatory cytokines and L-arginine metabolism enzymes. Our results will provide novel information about dermotropic L. infantum isolates and the impact of their infection on host macrophages.

Palavras-chave

atypical cutaneous leishmaniasis, field isolates, Leishmania infantum.