Metagenomic characterisation of microbes associated with Lutzomyia longipalpis, vector of leishmaniasis

Leishmaniasis is a vector-borne neglected infectious disease of worldwide incidence and its most severe clinical form is visceral leishmaniasis (VL). In Latin America VL is caused by Leishmania infantum chagasi and is transmitted by Lutzomyia longipalpis. This phlebotomine fly is only found in the New World, with a wide distribution from Mexico to Argentina (Grimaldi et al., 1989). Between 1925 and 1989 only 14 leishmaniasis human cases were reported in Argentina and none was attributed to Le. chagasi. Moreover, there were only two isolated reports of Lu. longipalpis (in 1951 and 2000) which were not associated with VL (Salomon et al., 2001). Nevertheless, due to the indiscriminate advance of urbanisation and the poverty and inadequate health conditions this generates, the first VL outbreak in Argentina was recently reported (Salomon et al., 2008). The measures that have been developed to treat leishmania infections and to control vectors have not been satisfactory. Controlling this infectious disease is difficult due to the diversity of the intervening factors (leishmania parasites, sand flies and host reservoirs) and any intervention must consider these differences. Evidence of a possible influence of gut microbiota on the parasite life cycle has been reported for some insect vectors, including sandflies and tsetse flies. These preliminary studies indicate that gut microbiota might well contribute to the modulation of insect vector competence but, in most cases, the mechanisms involved are mostly unknown. Metagenomics is a new and rapidly developing field which analyses the complex genomes of microbial niches in an environmental sample. The widespread use of next-generation sequencing technology to explore microbial communities has brought to light greater microorganism diversity. In this context, the metagenomic sequencing of microorganisms associated with Lu. longipalpis will enable the assembly of a comprehensive inventory of microbiota in these sandfly populations. This inventory will provide the necessary foundation to address the significance of candidate vector-specific bioinsecticides and microorganisms capable of regulating vector competence.