Investigation of bacterial microbiota variability in two allopatric populations of Nyssomyia umbratilis, susceptible and nonsusceptible to Leishmania (Viannia) guyanensis infection in the Amazon region.

BACKGROUND: Sand flies of the species Nyssomyia umbratilis (Diptera: Psychodidae: Phlebotominae) are vectors of the parasite Leishmania (Viannia) guyanensis, one of the etiological agents of cutaneous leishmaniasis in the Amazon region. In addition, Ny. umbratilis is a cryptic species, with populations showing differences in their ability to transmit the parasite. For instance, populations of Ny. umbratilis from the Manacapuru municipality (MAN), located on the south bank of the Negro river, in the Amazonas state of Brazil, shows refractoriness to Leishmania infection, while populations from Rio Preto da Eva municipality (RPE), located on the north bank of the Negro river, are susceptible to infection. This lack of vectorial capacity may be caused by several factors, including the intestinal bacterial microbiota of sand flies.

METHODS: In this work, we carried out a metagenomic study of the intestinal microbiota of Ny. umbratilis populations from MAN and RPE. Ny. umbratilis females were collected in forested areas, sand fly midguts were dissected, DNA was extracted, and the 16 S rRNA gene sequenced to identify the bacterial composition of the microbiota.

RESULTS: In total, 16 phyla, 33 classes, 49 orders, 93 families, and 112 genera of bacteria were identified. The phylum Proteobacteria was the most frequent (85.9%) in both localities, followed by the phyla Bacteroidetes, Actinobacteria, and Firmicutes with, 9.9%, 4.9%, and 4.4%, respectively. In MAN, 84 genera were identified and 79 in RPE, with MAN having a greater richness compared with RPE. Among these, the genera Rickettsia, Prevotella, Porphyromonas, Peptostreptococcus, and Caulobacter were the most prevalent in MAN, and the genera Rickettsia, Prevotella, Cryocola, Porphyromonas, and Caulobacter were the most prevalent in RPE.

CONCLUSIONS: Bacterial microbiota from MAN insects presents a greater diversity in relation to the RPE insects. Some of the identified bacteria have the potential to be used in alternative transmission control approaches as the development of transgenic vectors, and also, bacteria found exclusively in MAN sand flies may be candidates for a future transmission control approach to combat leishmaniasis in the Amazon region.