Comparative genomics of Leishmania donovani progeny from genetic crosses in two sand fly species and impact on the diversity of diagnostic and vaccine candidates.

Sand fly transmitted Leishmania species are responsible for severe, wide ranging, visceral and cutaneous leishmaniases. Genetic exchange can occur among natural Leishmania populations and hybrids can now be produced experimentally, with limitations. Feeding Phlebotomus orientalis or Phlebotomus argentipes on two strains of Leishmania donovani yielded hybrid progeny, selected using double drug resistance and fluorescence markers. Fluorescence activated cell sorting of cultured clones derived from these hybrids indicated diploid progeny. Multilocus sequence typing of the clones showed hybridisation and nuclear heterozygosity, although with inheritance of single haplotypes in a kinetoplastid target. Comparative genomics showed diversity of clonal progeny between single chromosomes, and extraordinary heterozygosity across all 36 chromosomes. Diversity between progeny was seen for the HASPB antigen, which has been noted previously as having implications for design of a therapeutic vaccine. Genomic diversity seen among Leishmania strains and hybrid progeny is of great importance in understanding the epidemiology and control of leishmaniasis. As an outcome of this study we strongly recommend that wider biological archives of different Leishmania species from endemic regions should be established and made available for comparative genomics. However, in parallel, performance of genetic crosses and genomic comparisons should give fundamental insight into the specificity, diversity and limitations of candidate diagnostics, vaccines and drugs, for targeted control of leishmaniasis.

Molecular typing reveals the co-existence of two transmission cycles of American cutaneous leishmaniasis in the Andean Region of Venezuela with Lutzomyia migonei as the vector

BACKGROUND The transmission routes for American cutaneous leishmaniasis (ACL) are in flux, so studies examining its transmission in humans, mammalian hosts, and sand fly vectors are urgently needed. OBJECTIVES The aim of this work was understand the epidemiological cycles of Leishmania spp., which causes ACL in the Andean Region of Venezuela, by identifying the Leishmania and the sand fly species involved in human and dog infections. METHODS Thirty-one biopsies from patients in Mérida and Táchira states with suspected ACL were studied by both parasitological tests (cultures and hamster inoculation) and a molecular test [Internal transcribed spacer 1 (ITS1) nested polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP)]. We also conducted a survey to detect Leishmania infection in dogs (Immunifluorescence antibody test and ITS1 nested PCR-RFLP) and sand flies (ITS1 nested PCR-RFLP) from El Carrizal, a highly endemic focus of ACL in Venezuela. FINDINGS Three different Leishmania species were identified in the clinical samples from humans (Leishmania braziliensis, L. guyanensis, and L. mexicana) and dogs (L. guyanensis and L. mexicana). The predominant sand fly species found were those from the Verrucarum group (infected with L. mexicana) and Lutzomyia migonei (infected with L. guyanensis and L. mexicana). MAIN CONCLUSIONS We show that Lu. migonei may be the putative vector in two ACL epidemiological cycles, involving L. guyanensis and L. mexicana. We also report for the first time the presence of L. guyanensis in domestic animals.

Drug discovery for Chagas disease should consider Trypanosoma cruzi strain diversity

This opinion piece presents an approach to standardisation of an important aspect of Chagas disease drug discovery and development: selecting Trypanosoma cruzi strains for in vitro screening. We discuss the rationale for strain selection representing T. cruzi diversity and provide recommendations on the preferred parasite stage for drug discovery, T. cruzi discrete typing units to include in the panel of strains and the number of strains/clones for primary screens and lead compounds. We also consider experimental approaches for in vitro drug assays. The Figure illustrates the current Chagas disease drug-discovery and development landscape.

Identificación bioquímica de las leishmanias / Biochemical identification of the leishmanias

...En general se recomienda que las investigaciones iniciales con isoenzimas se realicen en detalle a escala regional, y que aborden problemas epidemiológicos específicos e importantes. Es posible mantener la continuidad con los estudios futuros si en todas las comparaciones se utilizan estirpes representativas de Leishmania. Con el tiempo, estas proporcionarán un medio para comparar aislamientos provenientes de distintas regiones geográficas. En condiciones ideales, al menos por lo que se refiere a las cepas de Leishmania de referencia, los perfiles de isoenzimas deben usarse en combinación con otros métodos de caracterización como el cariotipo molecular o la capacidad de reacción frente a anticuerpos monoclonales... (AU)

Chagas' disease in the Amazon Basin: V. Periurban palms as habitats of Rhodnius robustus and Rhodnius pictipes - triatomine vectors of Chagas' disease.

Rhodnius robustus e/ou Rhodnius pictipes, infectados com Trypanosoma cruzi foram comumente encontrados, em grande numero, nas palmeiras Maximiliana regia (inaja), Acrocomia sclerocarpa (mucaja) e Orbignya speciosa (babacu) na Amazonia brasileira. O marsupial Didelphis marsupialis foi o animal encontrado mais frequentemente nas palmeiras associadas a alta prevalencia de triatomineos. R. pictipes que e atraido pela luz nas residencias de palmeiras vizinhas, provavelmente e a fonte de um caso agudo de doenca de Chagas nas vizinhancas de Belem. Sugere-se que as palmeiras albergando triatomineos poderiam ser relacionadas com infeccoes humanas de doenca de Chagas nos Estados de Amazonas e Rondonia. Sugere-se, tambem, possiveis metodos de controle

Biogeography of Triatominae (Hemiptera: Reduviidae) in Ecuador: implications for the design of control strategies

Chagas disease control strategies strongly depend on the triatomine vector species involved in Trypanosoma cruzi transmission within each area. Here we report the results of the identification of specimens belonging to various species of Triatominae captured in Ecuador (15 species from 17 provinces) and deposited in the entomological collections of the Catholic University of Ecuador (Quito), Instituto Oswaldo Cruz (Brazil), the Natural History Museum London (UK), the London School of Hygiene and Tropical Medicine (UK), the National Institute of Hygiene (Quito), and the Vozandes Hospital (Quito). A critical review of published information and new field records are presented. We analysed these data in relation to the life zones where triatomines occur (11 life zones, excluding those over 2,200 m altitude), and provide biogeographical maps for each species. These records are discussed in terms of epidemiological significance and design of control strategies. Findings relevant to the control of the main vector species are emphasised. Different lines of evidence suggest that Triatoma dimidiata is not native to Ecuador-Peru, and that synanthropic populations of Rhodnius ecuadoriensis in southern Ecuador-northern Peru might be isolated from their sylvatic conspecifics. Local eradication of T. dimidiata and these R. ecuadoriensis populations might therefore be attainable. However, the presence of a wide variety of native species indicates the necessity for a strong longitudinal surveillance system

The triatomines of northern Peru, with emphasis on the ecology and infection by Trypanosomes of Rhodnius ecuadoriensis (Triatominae)

Information on the distribution and synanthropic behaviour of triatomines is essential for Chagas disease vector control. This work summarises such information from northern Peru, and presents new data on Rhodnius ecuadoriensis - an important local vector infesting 10-35 percent of dwellings in some zones. Three species are strongly synanthropic and may be suitable targets for chemical control of domestic/peridomestic bug populations. Panstrongylus herreri, the main domestic vector in the area, is probably present in sylvatic ecotopes in the Marañón river system. R. ecuadoriensis and Triatoma dimidiata seem exclusively domestic; biogeographical and ecological data suggest they might have spread in association with humans in northern Peru. Confirmation of this hypothesis would result in a local eradication strategy being recommended. Presence of trypanosome natural infection was assessed in 257 R. ecuadoriensis; Trypanosoma rangeli was detected in 4 percent of bugs. Six further triatomine species are potential disease vectors in the region (T. carrioni, P. chinai, P. rufotuberculatus, P. geniculatus, R. pictipes, and R. robustus), whilst Eratyrus mucronatus, E. cuspidatus, Cavernicola pilosa, Hermanlentia matsunoi, and Belminus peruvianus have little or no epidemiological significance. A strong community-based entomological surveillance system and collaboration with Ecuadorian public health authorities and researchers are recommended

Identificación bioquímica de las leishamanias / Biochemical identification of leishmanias

Las dificultades para clasificarlas leishmanias según su comportamiento en los mamíferos húespedes y en los flebótomos vectores han planteado la necesidad de establecer criterios de clasificación que no dependan de estas complejas relaciones recíprocas. La electroforesis de isoenzimas... es un instrumento taxonómico útil para tal propósito. De hecho, se ha convertido en el método bioquímico más utilizado para distinguir las leishmanias, y ha ayudado mucho a comprender la epidemiología de la leishmaniasis cutánea y la visceral. En esencia, la electroforesis de isoenzimas... consta de los pasos siguientes: se preparan extractos solubres no purificados de los microorganismos en estudio; los extractos se colocan en una placa para electroforesis; los componentes del extracto se dirigen hacia el cátodo o el ánodo según su carga elétrica; la placa se cubre con un sustrato específico susceptible de ser alterado por la enzima escogida; por último, mediante una coloración capaz de revelar la ubicación del sustrato alterado, se determina el desplazamiento de la enzima sobre la placa. Las diferencias en los perfiles isoenzimáticos resultantes indican diferencias en los genes que regulan la producción de las enzimas correspondientes. Si se somete a prueba un número suficiente de enzimas, la ausencia de dichas diferencias indica que las poblaciones de leishmanias estudiadas son muy similares. Una de las complicaciones de esta prueba es que las infecciones mixtas de mamíferos o vectores por más de una especie de leishmania tornan confusa la interpretación de los datos de isoenzimas.... Por conseguiente es aconsejable clonar estirpes estandarizadas y representativas de Leishmania para usarlas al hacer compraciones amplias de isoenzimas...

O ecotopo de Panstrongylus megistus (Hemiptera, Reduviidae) na Floresta do Horto (Rio de Janeiro). / The ecotope of Panstrongylus megistus (Hemiptera, Reduviidae) in the Horto Forest (Rio de Janeiro)

Os principais mamiferos capturados em 10 dias de trabalho na reserva do Horto do Rio de Janeiro, foram Didelphis marsupialis e Metachirus nudicaudatus. Somente D. marsupialis foi encontrado infectado com Trypanosoma cruzi.Utilizando-se um sistema aperfeicoado de seguir mamiferos,foi possivel recuperar em seus ninhos 7 D. marsupialis, 8 M. nudicaudatus e 1 Marmosa sp. Em ninho de D. marsupialis, localizado em buraco de arvore, foram capturados exemplares de P. megistus infectados com T. cruzi; e num segundo ninho, em outra arvore, coletou-se um exemplar de Parabelminus carioca femea. Ao contrario dos de D. marsupialis, todos os ninhos de M. nudicaudatus foram encontrados no chao ou ate 1 metro acima do solo, nao tendo sido observado M. nudicaudatus em copas de arvores. Embora comum, esta especie nao e considerada de importancia na manutencao de P. megistus na reserva florestal do Horto do Rio de Janeiro

Epidemiologia de um caso de doença de Chagas na Ilha do Mosqueiro - Pará / Epidemiology of a case of Chagas' disease in the Mosqueiro Island - Para (Brazil)

Os autores apresentam os resultados do estudo epidemiológico de um caso autóctone da fase aguda da doença de Chagas na ilha do Mosqueiro. Estado do Pará, aproximadamente 75km da capital, Belém. O caso já havia sido objeto de uma publicaçäo anterior. Agora säo apresentadas informaçöes epidemiológicas. Nas proximidades da casa do paciente foram capturados em duas palmeiras de Inajá (Maximilian regia) e em uma da Mucajá (Acrocomia sclerocarpia) 114 triatomineos: Rhodnius pictipes, R. robustus, Panstrongylus lignarius, P. geniculatus e Microtriatoma trinidadensis, com tripanossomas em 31 deles. Na casa do paciente foram encontrados exemplares de Rhodnius pictipes, infectados com formas metacíclicas do Trypanosoma cruzi. Em 14 marsupiais, capturados na localidade, haviam 3 infectados com organismos semelhantes ao T. cruzi. A eletroforese dos isoenzimas nos tripanossomas isolados do paciente, de R. pictipes e de Didelphis marsupialis os classificou como zimodema 1. Os autores concluem que a doença de Chagas do paciente teve origem silvestre

Eletroforese de enzimas para estudos de triatomíneos com referência especial a subpopulaçöes de Panstrongylus megistus / Enzyme electrophoresis for studies of Triatomidae with special reference to Panstrongylus megistus subpopulations

Eletroforese de isoenzimas foi utilizada para investigar heterogeneidade intra-específica em triatomíneos e diferenças isoenzimáticas entre três subpopulaçöes de P.megistus, procedentes de Pernambuco, da Bahia e do Rio de Janeiro. Foram também analisados os caracteres morfológicos das três subpopulaçöes de P. megistus. Das 24 enzimas estudadas, 15 funcionaram bem (ASAT, ALAT, PGM, GPI, ME, MDH, ACON, ICD, PEP, PK, ENO, HK, MPI, ES e HEX). Dentre as 14 enzimas estudadas, 12 separaram as três espécies entre si R. prolixus, D. maxima e T. infestans e duas enzimas (GPI e PK) separaram as duas espécies (D. maxima e T.infestans) da terceira espécie (R. prolixus). Através dos resultados obtidos, observou-se a ausência de diferenças entre as três subpopulaçöes de P. megistus, porém pequenas diferenças morfológicas foram constatadas. A evidência indica que o clima é mais importante que a heterogeneidade genética no controle do comportamento do P megistus no norte e no sul do país. Constatou-se que e possível com triatomíneos a aplicaçäo de eletroforese em estudos filogenéticos e de resistência contra inseticidas