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Molecular taxonomy of the two Leishmania vectors Lutzomyia umbratilis and Lutzomyia anduzei (Diptera: Psychodidae) from the Brazilian Amazon.

ABSTRACT: BACKGROUND: Lutzomyia umbratilis (a probable species complex) is the main vector of Leishmania guyanensis in the northern region of Brazil. Lutzomyia anduzei has been implicated as a secondary vector of this parasite. These species are closely related and exhibit high morphological similarity in the adult stage; therefore, they have been wrongly identified, both in the past and in the present. This shows the need for employing integrated taxonomy. METHODS: With the aim of gathering information on the molecular taxonomy and evolutionary relationships of these two vectors, 118 sequences of 663 base pairs (barcode region of the mitochondrial DNA cytochrome oxidase I - COI) were generated from 72 L. umbratilis and 46 L. anduzei individuals captured, respectively, in six and five localities of the Brazilian Amazon. The efficiency of the barcode region to differentiate the L. umbratilis lineages I and II was also evaluated. The data were analyzed using the pairwise genetic distances matrix and the Neighbor-Joining (NJ) tree, both based on the Kimura Two Parameter (K2P) evolutionary model. RESULTS: The analyses resulted in 67 haplotypes: 32 for L. umbratilis and 35 for L. anduzei. The mean intra-specific genetic distance was 0.008 (0.002 to 0.010 for L. umbratilis; 0.008 to 0.014 for L. anduzei), whereas the mean interspecific genetic distance was 0.044 (0.041 to 0.046), supporting the barcoding gap. Between the L. umbratilis lineages I and II, it was 0.009 to 0.010. The NJ tree analysis strongly supported monophyletic clades for both L. umbratilis and L. anduzei, whereas the L. umbratilis lineages I and II formed two poorly supported monophyletic subclades. CONCLUSIONS: The barcode region clearly separated the two species and may therefore constitute a valuable tool in the identification of the sand fly vectors of Leishmania in endemic leishmaniasis areas. However, the barcode region had not enough power to separate the two lineages of L. umbratilis, likely reflecting incipient species that have not yet reached the status of distinct species.

SUBMITTER: Scarpassa VM

PROVIDER: S-EPMC3847350 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Molecular taxonomy of the two Leishmania vectors Lutzomyia umbratilis and Lutzomyia anduzei (Diptera: Psychodidae) from the Brazilian Amazon.

Scarpassa Vera Margarete VM Alencar Ronildo Baiatone RB

Parasites & vectors 20130911 1

<h4>Background</h4>Lutzomyia umbratilis (a probable species complex) is the main vector of Leishmania guyanensis in the northern region of Brazil. Lutzomyia anduzei has been implicated as a secondary vector of this parasite. These species are closely related and exhibit high morphological similarity in the adult stage; therefore, they have been wrongly identified, both in the past and in the present. This shows the need for employing integrated taxonomy.<h4>Methods</h4>With the aim of gathering ...[more]

PMID: 24021095

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Project description:BackgroundThe Lutzomyia longipalpis complex has a wide but discontinuous distribution in Latin America, extending throughout the Neotropical realm between Mexico and northern Argentina and Uruguay. In the Americas, this sandfly is the main vector of Leishmania infantum, the parasite responsible for Visceral Leishmaniasis (VL). The Lu. longipalpis complex consists of at least four sibling species, however, there is no current consensus on the number of haplogroups, or on their divergence. Particularly in Argentina, there have been few genetic analyses of Lu. longipalpis, despite its southern expansion and recent colonization of urban environments. The aim of this study was to analyze the genetic diversity and structure of Lu. longipalpis from Argentina, and to integrate these data to re-evaluate the phylogeography of the Lu. longipalpis complex using mitochondrial markers at a Latin American scale.Methodology/principal findingsGenetic diversity was estimated from six sites in Argentina, using a fragment of the ND4 and the 3´ extreme of the cyt b genes. Greatest genetic diversity was found in Tartagal, Santo Tomé and San Ignacio. There was high genetic differentiation of Lu. longipalpis in Argentina using both markers: ND4 (FST = 0.452, p < 0.0001), cyt b (FST = 0.201, p < 0.0001). Genetic and spatial Geneland analyses reveal the existence of two primary genetic clusters in Argentina, cluster 1: Tartagal, Santo Tomé, and San Ignacio; cluster 2: Puerto Iguazú, Clorinda, and Corrientes city. Phylogeographic analyses using ND4 and cyt b gene sequences available in GenBank from diverse geographic sites suggest greater divergence than previously reported. At least eight haplogroups (three of these identified in Argentina), each separated by multiple mutational steps using the ND4, are differentiated across the Neotropical realm. The divergence of the Lu. longipalpis complex from its most recent common ancestor (MRCA) was estimated to have occurred 0.70 MYA (95% HPD interval = 0.48-0.99 MYA).Conclusions/significanceThis study provides new evidence supporting two Lu. longipalpis genetic clusters and three of the total eight haplogroups circulating in Argentina. There was a high level of phylogeographic divergence among the eight haplogroups of the Lu. longipalpis complex across the Neotropical realm. These findings suggest the need to analyze vector competence, among other parameters intrinsic to a zoonosis, according to vector haplogroup, and to consider these in the design and surveillance of vector and transmission control strategies.

Project description:Several parameters should be addressed before incriminating a vector for Leishmania transmission. Those may include its ability to become infected by the same Leishmania species found in humans, the degree of attractiveness for reservoirs and humans and capacity to sustain parasite infection under laboratory conditions. This study evaluated the vectorial capacity of Lutzomyia cruzi for Leishmania infantum and gathered information on its ability to harbor L. amazonensis. Laboratory-reared Lu. cruzi were infected experimentally by feeding them on dogs infected naturally with L. infantum and hamsters infected with L. amazonensis. Sand fly attractiveness to dogs and humans was determined using wild caught insects. The expected daily survival of infected Lu. cruzi, the duration of the gonotrophic cycle, and the extrinsic incubation period were also investigated for both parasites. Vector competence was investigated for both Leishmania species. The mean proportion of female sand flies that fed on hosts was 0.40. For L. infantum and L. amazonensis, Lu. cruzi had experimental infection rates of 10.55% and 41.56%, respectively. The extrinsic incubation period was 3 days for both Leishmania species, regardless of the host. Survival expectancy of females infected with L. infantum and L. amazonensis after completing the gonotrophic cycle was 1.32 and 0.43, respectively. There was no association between L. infantum infection and sand fly longevity, but L. amazonensis-infected flies had significantly greater survival probabilities. Furthermore, egg-laying was significantly detrimental to survival. Lu. cruzi was found to be highly attracted to both dogs and humans. After a bloodmeal on experimentally infected hosts, both parasites were able to survive and develop late-stage infections in Lu. cruzi. However, transmission was demonstrated only for L. amazonensis-infected sand flies. In conclusion, Lu. cruzi fulfilled several of the requirements of vectorial capacity for L. infantum transmission. Moreover, it was also permissive to L. amazonensis.

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Dataset Information

Molecular taxonomy of the two Leishmania vectors Lutzomyia umbratilis and Lutzomyia anduzei (Diptera: Psychodidae) from the Brazilian Amazon.

Publications

Molecular taxonomy of the two Leishmania vectors Lutzomyia umbratilis and Lutzomyia anduzei (Diptera: Psychodidae) from the Brazilian Amazon.

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