Marine Ginouves

Presence of Leishmania RNA Virus 1 in Leishmania guyanensis Increases the Risk of First-Line Treatment Failure and Symptomatic Relapse

Treatment failure and symptomatic relapse are major concerns in American tegumentary leishmaniasis (TL). Such complications are seen frequently in Leishmania guyanensis infections, in which patients respond variously to first-line antileishmanials and are more prone to develop chronic cutaneous leishmaniasis. The factors underlying this pathology, however, are unknown. Recently, we reported that a double-stranded RNA virus, Leishmania RNA virus 1 (LRV1), nested within L. guyanensis parasites is able to exacerbate experimental murine leishmaniasis by inducing a hyperinflammatory response. This report investigates the prevalence of LRV1 in human L. guyanensis infection and its effect on treatment efficacy, as well as its correlation to symptomatic relapses after the completion of first-line treatment. In our cohort of 75 patients with a diagnosis of primary localized American TL, the prevalence of LRV1-positive L. guyanensis infection was elevated to 58%. All patients infected with LRV1-negative L. guyanensis were cured after 1 dose (22 of 31 [71%]) or 2 doses (31 of 31 [100%]) of pentamidine. In contrast, 12 of 44 LRV1-positive patients (27%) presented with persistent infection and symptomatic relapse that required extended therapy and the use of second-line drugs. Finally, LRV1 presence was associated with a significant increase in levels of intra-lesional inflammatory markers. In conclusion, LRV1 status in L. guyanensis infection is significantly predictive (P = .0009) of first-line treatment failure and symptomatic relapse and has the potential to guide therapeutic choices in American TL.

Prevalence and Distribution of Leishmania RNA Virus 1 in Leishmania Parasites from French Guiana

In South America, the presence of the Leishmania RNA virus type 1 (LRV1) was described in Leishmania guyanensis and Leishmania braziliensis strains. The aim of this study was to determine the prevalence distribution of LRV1 in Leishmania isolates in French Guiana given that, in this French overseas department, most Leishmania infections are due to these parasite species. The presence of the virus was observed in 74% of Leishmania spp. isolates, with a highest presence in the internal areas of the country.

Comparison of Tetrazolium Salt Assays for Evaluation of Drug Activity against Leishmania spp.

ABSTRACT In French Guiana, leishmaniasis is an essentially cutaneous infection. It constitutes a major public health problem, with a real incidence of 0.2 to 0.3%. Leishmania guyanensis is the causal species most frequently encountered in French Guiana. The treatment of leishmaniasis is essentially drug based, but the therapeutic compounds available have major side effects (e.g., liver damage and diabetes) and must be administered parenterally or are costly. The efficacy of some of these agents has declined due to the emergence of resistance in certain strains of Leishmania. There is currently no vaccine against leishmaniasis, and it is therefore both necessary and urgent to identify new compounds effective against Leishmania. The search for new drugs requires effective tests for evaluations of the leishmanicidal activity of a particular molecule or extract. Microculture tetrazolium assays (MTAs) are colorimetric tests based on the use of tetrazolium salts. We compared the efficacies of three tetrazolium salts—3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT), and 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium (WST-8)—for quantification of the promastigotes of various species of Leishmania. We found that the capacity of Leishmania to metabolize a tetrazolium salt depended on the salt used and the species of Leishmania. WST-8 was the tetrazolium salt best metabolized by L. guyanensis and gave the best sensitivity.

Natural Leishmania (Viannia) infections of phlebotomines (Diptera: Psychodidae) indicate classical and alternative transmission cycles of American cutaneous leishmaniasis in the Guiana Shield, Brazil

From 1996 to 1999 multi-trapping methods (Center of Diseases Control, CDC) light traps, light-baited Shannon traps, and aspiration on tree bases) were used to study the phlebotomine fauna of the “Serra do Navio” region of the Brazilian State of Amapá, which is part of the Guiana Shield. Fifty-three species were identified among 8,685 captured individuals. The following species, associated with the transmission of American cutaneous leishmaniasis in Amazonian Brazil, were captured: Nyssomyia umbratilis (3,388), Psychodopygus squamiventris maripaensis (995), Ny. anduzei (550), Trichophoromyia ubiquitalis (400), Ny. whitmani (291), Ps. paraensis (116), and Bichromomyia flaviscutellata (50). Flagellate infections were detected in 45 flies. Of the 19 parasites isolated in vitro, 15 were Leishmania (Viannia) guyanensis (13 in Ny. umbratilis, 1 in Ny. whitmani, 1 in Ny. anduzei) and three were L. (V.) naiffi (2 in Ps. s. maripaensis, 1 in Ny. anduzei). The results indicate the participation of three phlebotomine species in the transmission of L. (V.) guyanensis and two species in that of L. (V.) naiffi, and show that the same phlebotomine species is involved in the transmission of different Leishmania (Viannia) species in the Guianan/Amazon region. A review of the literature together with the results of the present study, and other published and unpublished results, indicate that eight phlebotomine species potentially participate in the transmission of Leishmania (Viannia) naiffi in Amazonia.

Unraveling the genetic diversity and phylogeny of Leishmania RNA virus 1 strains of infected Leishmania isolates circulating in French Guiana

Introduction Leishmania RNA virus type 1 (LRV1) is an endosymbiont of some Leishmania (Vianna) species in South America. Presence of LRV1 in parasites exacerbates disease severity in animal models and humans, related to a disproportioned innate immune response, and is correlated with drug treatment failures in humans. Although the virus was identified decades ago, its genomic diversity has been overlooked until now. Methodology/Principles findings We subjected LRV1 strains from 19 L. (V.) guyanensis and one L. (V.) braziliensis isolates obtained from cutaneous leishmaniasis samples identified throughout French Guiana with next-generation sequencing and de novo sequence assembly. We generated and analyzed 24 unique LRV1 sequences over their full-length coding regions. Multiple alignment of these new sequences revealed variability (0.5%–23.5%) across the entire sequence except for highly conserved motifs within the 5’ untranslated region. Phylogenetic analyses showed that viral genomes of L. (V.) guyanensis grouped into five distinct clusters. They further showed a species-dependent clustering between viral genomes of L. (V.) guyanensis and L. (V.) braziliensis, confirming a long-term co-evolutionary history. Noteworthy, we identified cases of multiple LRV1 infections in three of the 20 Leishmania isolates. Conclusions/Significance Here, we present the first-ever estimate of LRV1 genomic diversity that exists in Leishmania (V.) guyanensis parasites. Genetic characterization and phylogenetic analyses of these viruses has shed light on their evolutionary relationships. To our knowledge, this study is also the first to report cases of multiple LRV1 infections in some parasites. Finally, this work has made it possible to develop molecular tools for adequate identification and genotyping of LRV1 strains for diagnostic purposes. Given the suspected worsening role of LRV1 infection in the pathogenesis of human leishmaniasis, these data have a major impact from a clinical viewpoint and for the management of Leishmania-infected patients.

Composition and antifungal activity of the essential oil of Nashia inaguensis Millsp. (Verbenaceae) cultivated in French Guiana

Abstract This study reports the chemical composition of the essential oil of Nashia inaguensis Millsp. organically cultivated in French Guiana. This essential oil was examined by a combination of GC/FID and GC-MS techniques. A total of thirty-one components accounting for 97% of the total GC/FID chromatogram were identified. The most abundant ones were carvacrol (23.1%), p-cymene (18.7%), γ-terpinene (14.6%), thymol methyl ether (10.3%), thymol (8.3%), trans-β-caryophyllene (8.0%) and myrcene (2.3%). The essential oil of N.inaguensis was tested for the first time for antifungal and antiparasitic activities against strains of several Candida spp. and Leishmania guyanensis respectively: the strong antimicrobial activity of this essential oil was confirmed in vitro by the definition of MIC values ranging from 125 μg/mL to 500 μg/mL according to the Candida species tested, while the anti-Leishmania activity assessed by the definition of an IC50 value seem negligible.

Use of the intramuscular route to administer pentamidine isethionate in Leishmania guyanensis cutaneous leishmaniasis increases the risk of treatment failure

BACKGROUND New world cutaneous leishmaniasis (NWCL) can be found in French Guiana as well as in several other parts of Central and South America. Leishmania guyanensis accounts for nearly 90% of cases in French Guiana and is treated with pentamidine isethionate, given by either intramuscular or intravenous injection. The military population is particularly exposed due to repeated missions in the rainforest. The purpose of the present study was to identify the factors associated with pentamidine isethionate treatment failure in a series of service members with L. guyanensis NWCL acquired in French Guiana. METHOD All the French service members reported as having acquired leishmaniasis in French Guiana from December 2013 to June 2016 were included. RESULTS Seventy-three patients infected with L. guyanensis were included in the final analysis. Patients treated with IV pentamidine isethionate had better response rates than those treated with IM pentamidine isethionate (p = 0.002, adjusted odds ratio (AOR) = 0.15, 95% CI [0.04-0.50]). The rate of treatment success was 85.3% (95% CI [68.9-95.0]) for IV pentamidine isethionate and 51.3% (95% CI [34.8-67.6]) for IM pentamidine isethionate. CONCLUSIONS The use of intramuscular pentamidine isethionate in the treatment of Leishmania guyanensis cutaneous leishmaniasis is associated with more treatment failures than intravenous pentamidine isethionate.

Chemical composition and antifungal activity of the essential oil of Varronia schomburgkii (DC.) Borhidi (Cordiaceae) from plants cultivated in French Guiana

Abstract This study reports for the first time the chemical composition of the essential oil of Varronia schomburgkii (DC.) Borhidi cultivated in French Guiana. This essential oil was examined by a combination of GC/FID and GC-MS techniques and was further tested for antifungal activity against several Candida strains, as well as for anti-leishmanial activity against the reference strain Leishmania guyanensis. A total of 45 components accounting for 93.61% of the total GC/FID chromatogram were identified. The essential oil is dominated by sesquiterpenes and oxygenated sesquiterpenes among which β-caryophyllene (46.99 ± 0.32%) is the major one. No anti-leishmania activity could be assessed, while a strong antimicrobial activity of this essential oil was evidenced in vitro against a Candida albicans strain by the definition of a MIC value of 250 μg/mL. V. schomburgkii essential oil might hence be considered in the future for the development of natural antifungal agents.

Corrigendum of the article: ‘Composition and antifungal activity of the essential oil of Nashia inaguensis Millsp. (Verbenaceae) cultivated in French Guiana’ published in the journal of essential oil research (DOI: 10.1080/10412905.2016.1142477)

Abstract In a recent publication (DOI: 10.1080/10412905.2016.1142477), we presented the composition and antifungal activity of the essential oil of allegedly Nashia inaguensis Millsp. (Verbenaceae) using material from plants cultivated in French Guiana. A recent taxonomic revision of the genus Nashia, including a complete description of N. inaguensis, called our attention, as certain morphological characters did not correspond with those of our voucher specimen. An accurate re-examination of the voucher specimen and the original cultivated plants, and a comparison with the complete description of Lippia species present in the Guianas, confirmed that the species we studied was actually L. micromera Schauer. The present corrigendum aims to revise the botanical characterization presented in the aforementioned article. The chemical composition and antifungal activity of the essential oil of interest are then discussed in light of this corrected taxonomic identification in comparison with previous studies of L. micromera essential oil. The authors apologize for the error.