Dengue virus infection induces chromatin remodeling at locus AAEL006536 in the midgut of Aedes aegypti / La infección por virus dengue induce remodelación de la cromatina en el locus AAEL006536 en el intestino medio de Aedes aegypti

Abstract: Objective: To identify and characterize Aedes aegypti's AAEL006536 gene proximal upstream cis-regulatory sequences activated by dengue virus infection. Materials and methods: A. aegypti Rockefeller strain mosquitoes were blood fed or infected with dengue virus 2. Open chromatin profiling was then carried out in pools of midguts from each group of mosquitoes. Results: The proximal upstream region does not contain open chromatin sites in the midguts of blood-fed mosquitoes as detected by FAIRE-qPCR. In contrast, two cis-regulatory sites were identified in the same upstream region of dengue virus-infected mosquito midguts. The distal sequence contains STAT-, REL- and C/EBP-type transcription factor binding sites. Conclusion: The activation of two proximal cis-regulatory sequences, induced by dengue virus infection, is mediated by chromatin remodeling mechanisms. Binding sites suggest a dengue virus infection-induced participation of immunity transcription factors in the up-regulation of this gene. This suggests the participation of the AAEL006536 gene in the mosquito's antiviral innate immune response.

Resumen: Objetivo: Identificar y caracterizar las secuencias reguladoras activadas por la infección por virus dengue en la región proximal del gen AAEL006536 de Aedes aegypti. Material y métodos: Mosquitos de la cepa Rockefeller de A. aegypti se infectaron con virus dengue o se alimentaron con sangre. Se obtuvieron los perfiles de cromatina abierta del locus en los intestinos de cada uno de los grupos. Resultados: Se identificaron dos sitios reguladores solo en los intestinos de mosquitos infectados por virus dengue. El sitio distal contiene sitios de unión a factores de transcripción tipo REL, STAT y C/EBP. Conclusiones: La activación de dos sitios reguladores proximales está mediada por la remodelación de la cromatina. Los sitios de unión a factores de transcripción en el sitio regulador distal sugieren la participación de las vías de inmunidad en la regulación del gen. Esto sugiere la participación de este gen en la respuesta inmune del mosquito frente a la infección viral.

Cutaneous Microflora from Geographically Isolated Groups of Bradysia agrestis, an Insect Vector of Diverse Plant Pathogens

Larvae of Bradysia agrestis, an insect vector that transports plant pathogens, were sampled from geographically isolated regions in Korea to identify their cutaneous fungal and bacterial flora. Sampled areas were chosen within the distribution range of B. agrestis; each site was more than 91 km apart to ensure geographical segregation. We isolated 76 microbial (fungi and bacteria) strains (site 1, 29; site 2, 29; site 3, 18 strains) that were identified on the basis of morphological differences. Species identification was molecularly confirmed by determination of universal fungal internal transcribed spacer and bacterial 16S rRNA gene sequences in comparison to sequences in the EzTaxon database and the NCBI GenBank database, and their phylogenetic relationships were determined. The fungal isolates belonged to 2 phyla, 5 classes, and 7 genera; bacterial species belonged to 23 genera and 32 species. Microbial diversity differed significantly among the geographical groups with respect to Margalef's richness (3.9, 3.6, and 4.5), Menhinick's index (2.65, 2.46, and 3.30), Simpson's index (0.06, 0.12, and 0.01), and Shannon's index (2.50, 2.17, and 2.58). Although the microbial genera distribution or diversity values clearly varied among geographical groups, common genera were identified in all groups, including the fungal genus Cladosporium, and the bacterial genera Bacillus and Rhodococcus. According to classic principles of co-evolutionary relationship, these genera might have a closer association with their host insect vector B. agrestis than other genera identified. Some cutaneous bacterial genera (e.g., Pseudomonas) displaying weak interdependency with insect vectors may be hazardous to agricultural environments via mechanical transmission via B. agrestis. This study provides comprehensive information regarding the cutaneous microflora of B. agrestis, which can help in the control of such pests for crop management.

Seasonality of Mansonia titillans during dam construction, Biritiba-Mirim, São Paulo State, Brazil / Sazonalidade de Mansonia titillans durante a construção de uma represa, Biritiba-Mirim, Estado de São Paulo, Brasil

A two and a half year survey was conducted at a dam in southeastern Brazil. Shannon Traps were used for sampling. Kruskal-Wallis test showed little relation between rainfall and abundance. The data clearly show three abundance peaks, all of them in the end of the dry season, in consonance with the scarce literature existent. Although Kruskal-Wallis Test did not find a clear preference for the dry season, Pairwise Wilcoxon Rank Test revealed a significant difference between Fall and Spring samples. Ma. titillans population had a peak on late winter/early spring, close to the begin of wet season.

Uma pesquisa de dois anos e meio foi realizada em uma represa no sudeste do Brasil. Foram utilizadas Armadilhas de Shannon para coleta. O teste Kruskal-Wallis mostrou pouca correlação entre a precipitação e abundância. Os dados mostram claramente três picos de abundância, todos eles no final da estação seca, em consonância com a escassa literatura existente. Apesar do teste de Kruskal-Wallis não ter encontrado uma clara preferência pela estação seca, o Teste de Wilcoxon par-a-par revelou uma diferença significativa entre as amostras do Outono e da Primavera. A população de Ma titillans tem um pico no fim do inverno/início da primavera, próximo ao início da estação chuvosa.

Sand flies (Diptera: Psychodidae) in a cerrado area of the Maranhão state, Brazil

The present paper aims to increase the knowledge on the sand fly fauna in the cerrado areas of Maranhão state in urban, rural and forest environments. The research was carried out from October 2007 to September 2008, between 18:00h and 06:00h, in the municipality of Chapadinha, northeast Maranhão. For insect sampling, CDC light traps were set up in peridomicile and domicile areas of urban and rural zones as well as in Cerrado and Gallery forests. The total of 1,401 specimens belonging to 17 species were sampled, all within the genus Lutzomyia. Lutzomyia longipalpis (Lutz & Neiva) (52.5 percent), Lu. evandroi (Costa Lima & Antunes) (18.3 percent), Lu. whitmani (Antunes & Coutinho) (12.1 percent), Lu. lenti (Mangabeira) (4.7 percent) and Lu. termitophila (Martins, Falcão & Silva) (4.0 percent) were the most frequently collected. From an epidemiological viewpoint, five from all of the collected species are vectors of leishmaniasis: Lu. longipalpis, Lu. whitmani, Lu. flaviscutellata (Mangabeira), Lu. gomezi (Nitzulescu) and Lu. chagasi (Costa Lima). Lutzomyia chagasi was registered for the first time in Maranhão state and Lu. saulensis (Floch & Abonnenc), Lu. monstruosa (Floch & Abonnenc) and Lu. gomezi were found for the first time in the eastern part of the state, since they had been reported only in the Amazonian region of Maranhão. Regarding to the studied environments, the urban chicken house had the highest number of specimens collected (801), while the Gallery Forest was the most diverse (15 species). This study demonstrates that the northeast cerrado exhibits a mixed sand fly fauna characterized by an extremely important species vectors assortment involved in the epidemiological cycle of leishmaniasis in Maranhão state.

Ants' role (Hymenoptera: Formicidae) as potential vectors of mycobacteria dispersion / Comportamento de formigas (Hymenoptera: Formicidae) como vetores potenciais de dispersão de micobactérias

Ants are found worldwide playing an important environmental role. Some species are considered as agricultural pests and potential risk to human life and public health acting as pathogens carriers. Ants as Paratrechina longicornis and Camponotus spp. have been found inside hospitals. The aim of this study was the research of mycobacteria in 138 samples of ants (137 Paratrechina longicornis and only one Camponotus spp.) which got into the laboratories of tuberculosis diagnosis. These ants were suspended in sterile saline solution and inoculated into Petragnani and Stonebrink media, incubated at 37° C until 90 days and the isolates were identified as environmental mycobacteria (1 Mycobacterium fortuitum peregrinum, 1 Mycobacterium smegmatis) and 1 Mycobacterium tuberculosis complex. These results showed that ants should also act as mechanical vectors of mycobacteria dissemination in risk environments, reinforcing their significance in public health.

As formigas têm uma distribuição mundial e representam importante papel no ecossistema. Algumas espécies são consideradas pragas para a agricultura e um risco potencial à vida humana e à saúde pública veiculando mecanicamente agentes patogênicos. Formigas como Paratrechina longicornis e Camponotus spp. têm sido encontradas em ambientes hospitalares. O foco do presente estudo foi a identificação de micobactérias em 138 amostras de formigas (137 Paratrechina longicornis e apenas uma Camponotus sp.), que tiveram acesso a áreas de laboratórios de diagnóstico de tuberculose. Essas formigas foram suspensas em solução salina estéril que foi semeada em meios de Petragnani e Stonebrink, incubadas a 37º C por até 90 dias e as estirpes de micobactérias isoladas foram identificadas pelas técnicas clássicas como micobactérias ambientais (sendo 1 Mycobacterium smegmatis, 2 Mycobacterium fortuitum peregrinum e 1 Mycobacterium tuberculosis). Esses resultados mostram que as formigas podem também se constituir vetores de dispersão de micobactérias em ambientes de risco, reforçando sua importância em saúde pública.

RNA Interference in Infectious Tropical Diseases

Introduction of double-stranded RNA (dsRNA) into some cells or organisms results in degradation of its homologous mRNA, a process called RNA interference (RNAi). The dsRNAs are processed into short interfering RNAs (siRNAs) that subsequently bind to the RNA-induced silencing complex (RISC), causing degradation of target mRNAs. Because of this sequence-specific ability to silence target genes, RNAi has been extensively used to study gene functions and has the potential to control disease pathogens or vectors. With this promise of RNAi to control pathogens and vectors, this paper reviews the current status of RNAi in protozoans, animal parasitic helminths and disease-transmitting vectors, such as insects. Many pathogens and vectors cause severe parasitic diseases in tropical regions and it is difficult to control once the host has been invaded. Intracellularly, RNAi can be highly effective in impeding parasitic development and proliferation within the host. To fully realize its potential as a means to control tropical diseases, appropriate delivery methods for RNAi should be developed, and possible off-target effects should be minimized for specific gene suppression. RNAi can also be utilized to reduce vector competence to interfere with disease transmission, as genes critical for pathogenesis of tropical diseases are knockdowned via RNAi.

RNA Interference in Infectious Tropical Diseases

Introduction of double-stranded RNA (dsRNA) into some cells or organisms results in degradation of its homologous mRNA, a process called RNA interference (RNAi). The dsRNAs are processed into short interfering RNAs (siRNAs) that subsequently bind to the RNA-induced silencing complex (RISC), causing degradation of target mRNAs. Because of this sequence-specific ability to silence target genes, RNAi has been extensively used to study gene functions and has the potential to control disease pathogens or vectors. With this promise of RNAi to control pathogens and vectors, this paper reviews the current status of RNAi in protozoans, animal parasitic helminths and disease-transmitting vectors, such as insects. Many pathogens and vectors cause severe parasitic diseases in tropical regions and it is difficult to control once the host has been invaded. Intracellularly, RNAi can be highly effective in impeding parasitic development and proliferation within the host. To fully realize its potential as a means to control tropical diseases, appropriate delivery methods for RNAi should be developed, and possible off-target effects should be minimized for specific gene suppression. RNAi can also be utilized to reduce vector competence to interfere with disease transmission, as genes critical for pathogenesis of tropical diseases are knockdowned via RNAi.

Estudo preliminar da preferência alimentar de Nyssomyia neivai (Pinto) e Nyssomyia whitmani (Antunes & Coutinho) (Diptera: Psychodidae) em área rural do Paraná / Preliminary study on feeding preference of Nyssomyia neivai (Pinto) and Nyssomyia whitmani (Antunes & Coutinho) (Diptera: Psychodidae) in a rural area of the State of Paraná, South Brazil

Dada a importância de flebotomíneos na epidemiologia da leishmaniose tegumentar americana, investigou-se a preferência alimentar desses insetos em relação aos animais domésticos comumente presentes no ambiente domiciliar de áreas rurais, onde a doença é endêmica. Os flebotomíneos foram coletados com armadilhas luminosas de Falcão, instaladas em gaiolas, cada uma com um dos animais domésticos selecionados para isca (suíno, cão, coelho ou galinha). Foram feitas 45 coletas, no Recanto Marista, município de Doutor Camargo, totalizando 135h de coletas por armadilha. Foram coletados 2.854 exemplares de flebotomíneos das seguintes espécies: Brumptomyia brumpti (Larousse), Evandromyia correalimai (Martins, Coutinho & Luz), Evandromyia cortelezzii (Brèthes), Expapillata firmatoi (Barreto, Martins & Pellegrino), Micropygomyia ferreirana (Barreto, Martins & Pellegrino), Migonemyia migonei (França), Nyssomyia neivai (Pinto), Nyssomyia whitmani (Antunes & Coutinho), Pintomyia fischeri (Pinto), Pintomyia monticola (Costa Lima), Pintomyia pessoai (Coutinho & Barreto), Psathyromyia lanei (Barreto & Coutinho) e Psathyromyia shannoni (Dyar). A espécie dominante foi N. neivai. Não houve preferência alimentar de N. neivai e N. whitmani em relação aos animais usados como iscas. Conclui-se que N. neivai e N. whitmani são oportunistas e, provavelmente, suas fêmeas ajustam os seus hábitos alimentares à disponibilidade de hospedeiros, sugerindo o ecletismo alimentar desses dípteros nos ambientes antrópicos.

Due to the importance of sandflies in the American cutaneous leishmaniasis epidemiology, we investigated the feeding preference of sandflies related to domestic animals common in domiciliary environments in endemic rural areas, where this disease occurs. The sandflies were collected with Falcão light traps, installed in cages, each one containing one domestic animal kind (pig, dog, rabbit or chicken), in Recanto Marista, in Doutor Camargo municipality. Forty five collections were made, totaling 135h of collections per trap. A total of 2,854 sandflies of the following species were collected: Brumptomyia brumpti (Larousse), Evandromyia correalimai (Martins, Coutinho & Luz), Evandromyia cortelezzii (Brèthes), Expapillata firmatoi (Barreto, Martins & Pellegrino), Micropygomyia ferreirana (Barreto, Martins & Pellegrino), Migonemyia migonei (França), Nyssomyia neivai (Pinto), Nyssomyia whitmani (Antunes & Coutinho), Pintomyia fischeri (Pinto), Pintomyia monticola (Costa Lima), Pintomyia pessoai (Coutinho & Barreto), Psathyromyia lanei (Barreto & Coutinho) and Psathyromyia shannoni (Dyar). The dominant species was N. neivai. N. neivai and N. whitmani did not show any feeding preference towards the animals used as bait. It was concluded that N. neivai and N. whitmani are opportunist and, probably, the females adjust their feeding habits to the availability of hosts, suggesting their feeding eclecticism in the anthropic environments.

Heteroptera as vectors of plant pathogens / Heterópteros como vetores de patógenos de plantas

A habilidade de insetos picadores-sugadores em transmitir doenças para as plantas está intimamente relacionada ao modo de alimentação e ao tecido alvo. Os percevejos são considerados deimportância econômica mínima como vetores de patógenos de plantas, embora tenham comportamento alimentar semelhante aos homópteros. Os modos de alimentação em Heteroptera incluem “dilaceraçãoe bombeamento”, penetração intracelular no tecido vascular, e um mecanismo de bomba osmótica paraadquirir os conteúdos celulares sem penetrar a membrana celular. A relação entre a taxonomia dos heterópteros, modo de alimentação e o tipo de patógeno transmitido é explorada através de um levantamento bibliográfico. A transmissão por percevejos de fungos, bactérias, vírus, fitoplasmas e trypanossomatídeos flagelados é sumarizada. Os trypanossomatídeos flagelados de plantas parecem ser hospedados ou transmitidos exclusivamente por Pentatomomorpha (Lygaeioidea, Coreoidea, Pentatomoidea, e Pyrrhocoroidea). A transmissão de bactérias e fungos ocorre entre famílias de ambas infraordens, mas representantes de Miridae (Cimicomorpha) são mais associados com bactérias, enquanto os de Pentatomidae e Coreidae (Pentatomomorpha) predominam como transmissores de fungos. Alguns casos de transmissão de fitoplasmas e vírus são documentados, mas Cimicomorpha (tradicionalmente categorizados como alimentadores do tipo dilacerador-bombeador) estão representados maisfreqüentemente do que o esperado, considerando-se a especificidade por determinados tecidos vegetais desses patógenos. A ênfase da literatura sobre a exclusividade ou predominância do papel dos homópteros como transmissores de doenças pode arrefecer o ímpeto inicial em estudar os percevejos como transmissores; entretanto, os resultados apresentados aqui indicam a necessidade de incluir ospercevejos em levantamentos de potenciais transmissores de doenças.

The ability of piercing-sucking insects to transmit plant disease is closely linked tofeeding mode and target tissue. The true bugs (Heteroptera) are generally considered to be of minimal importance as vectors of plant pathogens, although they share similar feeding behaviors with homopterans. Modes of feeding in Heteroptera include “lacerate-and-flush”, intracellular penetration to vascular tissue, and an osmotic pump mechanism to acquire cell contents without penetrating the cell membrane. The relationship between heteropteran taxonomy, feeding mode, and the type ofpathogens transmitted is explored through a literature survey of feeding behavior and vectoring capability. Transmission by true bugs of fungal pathogens, bacteria, viruses, phytoplasmas, and trypanosomatid flagellatesis summarized; no records exist of bugs transmitting spiroplasmas.Trypanosomatid flagellates of plants appear to be harbored or transmitted exclusively by Pentatomomorpha (Lygaeioidea, Coreoidea, Pentatomoidea, and Pyrrhocoroidea). Bacterial and fungal transmission occurs among families representing both infraorders of phytophagous Heteroptera, but Miridae (Cimicomorpha) are most closely associated with bacteria, whereas Pentatomidae and Coreidae (Pentatomomorpha) predominate in transmission of fungi. Few cases of transmission of phytoplasmas and viruses are documented, but Cimicomorpha (traditionally categorized as destructive lacerate-andflush feeders) are represented more frequently than expected, considering the tissue specificity of these pathogens. Literature emphasis on the exclusive or predominant role of homopterans as disease vectors may discourage initial investigations of true bugs; based on the results presented here, the necessity of including heteropterans in any survey of potential plant disease vectors is clear.

Occurrence of the malaria Vector Anopheles albimanus Wiedemman (Diptera: Culicidae) in Isla Fuerte, Colombia / Ocorrência do vetor da malária Anopheles albimanus wiedemann (Diptera: Psychodidae) em Isla Fuerte, Colômbia

Pela primeira vez, é registrada a ocorrência do Anopheles albimanus Wiedemann em Isla Fuerte, Colômbia. Um total de doze mosquitos fêmeas foi capturado com armadilha Shannon em um ambiente peridomiciliar da ilha. Discute-se a relevância epidemiológica desta descoberta.

This is the first report of the occurrence of Anopheles albimanus Wiedemann in Isla Fuerte, Colombia. Twelve female mosquitoes were collected using an illuminated Shannon trap in a peridomestic environment of the island. The epidemiological relevance of this finding is discussed.