In VitroMetacyclogenesis ofLeishmania (Viannia) braziliensisandLeishmania (Leishmania) amazonensisClinical Field Isolates, as Evaluated by Morphology, Complement Resistance, and Infectivity to Human Macrophages

Abstract

This study was designed to assess in vitro metacyclogenesis of Leishmania (Viannia) braziliensis and Leishmania (Leishmania) amazonensis clinical field isolates obtained from patient lesions (L. braziliensis IMG3 and PPS6m; L. amazonensis MAB6). Metacyclogenesis was evaluated by different criteria, namely, promastigote size (morphometric analysis and flow cytometry), surface modifications (loss of lectin or monoclonal antibody (mAb) binding, complement resistance), and infectivity to human macrophages. Growth curves were similar for all parasites evaluated. The various features analyzed were expressed in a high percentage of promastigotes at 6th and 10th days of culture and a low percentage at the 2nd day. However, in most isolates, these features, considered as markers of metacyclogenesis, seemed to develop with different time courses, since the percentages of metacyclic forms detected with each technique were usually different. Parasites from 6th or 10th day and those negatively selected with lectin or mAb similarly infected human macrophages. From all isolates analyzed, L. amazonensis PH8 and MAB6 showed the highest and the lowest levels of susceptibility, respectively, to leishmanicidal activity of IFN-γ/LPS-activated macrophages. Our results showed that by using different techniques to evaluate different aspects of metacyclogenesis (morphological and biochemical modifications) different percentages of metacyclic promastigotes can be detected in each isolate culture.

Identification and Biological Characterization ofLeishmania (Viannia) guyanensisIsolated from a Patient with Tegumentary Leishmaniasis in Goiás, a Nonendemic Area for This Species in Brazil

“…Corroborating the difficulties in identifying the Leishmania species relying on the clinical findings, our results did not show any difference in the monophasic-culture replication rates among the different isolates. In these cultures, Leishmania species were morphologically similar, and the in vitro growth profiles were similar to those previously described for L. (V.) braziliensis [ 34 ].…”

“…Moreover, L. flaviscutellata , present in Goiás, was found to transmit L. (V.) guyanensis . Besides, anteaters and opossums, considered as reservoir of L. (V.) guyanensis , are present in Goiás [ 1 , 8 , 14 , 30 – 34 ].…”

Evaluation of the efficacy of systemic miltefosine associated with photodynamic therapy with liposomal chloroaluminium phthalocyanine in the treatment of cutaneous leishmaniasis caused by Leishmania (L.) amazonensis in C57BL/6 mice

“…It is compared with the evolution or involution of the infiltration of the lesions before and after therapy, and this criterion has been successfully used in several experimental leishmaniasis studies. Moreover, the limiting dilution for the quantification of Leishmania is an established and more widely used method [2,[40][41][42][43]. Thus, outcomes can form the basis for further research, where the systemic adverse effects of this multimodal therapy could be more thoroughly investigated.…”

Liver infusion tryptose (LIT): the best choice for growth, viability, and infectivity of Leishmania infantum parasites

“…infantum promastigotes cultivated in Grace’s medium demonstrated a lower percentage of infected macrophages but high parasite load (as shown by optical microscopy and flow cytometry analysis). This can be explained by the nature of the medium which is largely used in many studies to induce infection in animal models (da Silva Jr. et al 2015 ; Silva et al 2018 ; Siripattanapipong et al 2019 ). Based on our data, we can suggest that Grace’s medium, instead of inducing procyclic promastigotes, probably induces the formation of metacyclic promastigotes that explains the high parasite load in the infected macrophages in vitro.…”