Abstract
BackgroundParasites of the genus Leishmania cause a broad spectrum of diseases, collectively known as leishmaniasis, in humans worldwide. American cutaneous leishmaniasis is a neglected disease transmitted by sand fly vectors including Lutzomyia intermedia, a proven vector. The female sand fly can acquire or deliver Leishmania spp. parasites while feeding on a blood meal, which is required for nutrition, egg development and survival. The microbiota composition and abundance varies by food source, life stages and physiological conditions. The sand fly microbiota can affect parasite life-cycle in the vector.MethodsWe performed a metagenomic analysis for microbiota composition and abundance in Lu. intermedia, from an endemic area in Brazil. The adult insects were collected using CDC light traps, morphologically identified, carefully sterilized, dissected under a microscope and the females separated into groups according to their physiological condition: (i) absence of blood meal (unfed = UN); (ii) presence of blood meal (blood-fed = BF); and (iii) presence of developed ovaries (gravid = GR). Then, they were processed for metagenomics with Illumina Hiseq Sequencing in order to be sequence analyzed and to obtain the taxonomic profiles of the microbiota.ResultsBacterial metagenomic analysis revealed differences in microbiota composition based upon the distinct physiological stages of the adult insect. Sequence identification revealed two phyla (Proteobacteria and Actinobacteria), 11 families and 15 genera; 87 % of the bacteria were Gram-negative, while only one family and two genera were identified as Gram-positive. The genera Ochrobactrum, Bradyrhizobium and Pseudomonas were found across all of the groups.ConclusionsThe metagenomic analysis revealed that the microbiota of the Lu. intermedia female sand flies are distinct under specific physiological conditions and consist of 15 bacterial genera. The Ochrobactrum, Bradyrhizobium and Pseudomonas were the common genera. Our results detailing the constituents of Lu. intermedia native microbiota contribute to the knowledge regarding the bacterial community in an important sand fly vector and allow for further studies to better understand how the microbiota interacts with vectors of human parasites and to develop tools for biological control.
Highlights
Parasites of the genus Leishmania cause a broad spectrum of diseases, collectively known as leishmaniasis, in humans worldwide
Parasites of the genus Leishmania cause a broad spectrum of diseases in humans worldwide, collectively known as leishmaniasis
After the sequences were quality checked and assembled, the UN group was clustered into 66 Operational taxonomic units (OTUs), the GR group into 30 OTUs, and the BF group into 40 OTUs; only 12, 9 and 8 OTUs in the UN, GR and BF groups respectively, were considered valid bacterial OTUs according to the cut-off value
Summary
Parasites of the genus Leishmania cause a broad spectrum of diseases, collectively known as leishmaniasis, in humans worldwide. American cutaneous leishmaniasis is a neglected disease transmitted by sand fly vectors including Lutzomyia intermedia, a proven vector. The sand fly microbiota can affect parasite life-cycle in the vector. Even though several Leishmania spp. have been described, Leishmania braziliensis is the main species causative of ACL and can be transmitted by different sand fly species in distinct endemic geographical regions. In the southeastern region of Brazil, Lutzomyia intermedia is the main vector of L. braziliensis [4, 5]. This opportunistic species is associated with forests, nature reserves and modified domestic and peridomestic environments, such as animal shelters [6,7,8]
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