Detection of immunogenic proteins from Anopheles sundaicussalivary glands in the human serum

The saliva of mosquitoes has an important role in the transmission of several diseases, including malaria, and contains substances with vasomodulating and immunomodulating effects to counteract the host physiological mechanisms and enhance pathogen transmission. As immunomodulatory components, salivary gland proteins can induce the generation of specific IgG antibodies in the host, which can be used as specific biomarkers of exposure to Anopheles sundaicus . The objective of this study was to identify immunogenic proteins from the salivary glands of Anopheles sundaicus by reaction with sera from individuals living in malaria-endemic areas who are thus exposed to Anopheles mosquitoes.

Aceptabilidad y eficacia de mosquiteros tratados con insecticida de larga duración Olyset® en un área endémica para malaria en Colombia / Acceptability and efficacy of long-lasting insecticidal nets Olyset® in a malaria endemic area of Colombia

En Colombia, el uso de mosquiteros es promovido por el Programa nacional de prevención y control de enfermedades transmitidas por vectores en áreas endémicas para malaria. A pesar de esto, son pocos los estudios realizados para evaluar su efectividad y en particular el grado de aceptabilidad por los usuarios lo cual es fundamental para mantener la adherencia a esta medida de control. En el presente estudio se evaluó, a pequeña escala, la aceptación de mosquiteros impregnados con insecticida de larga duración (Olyset®) y su efecto biológico en mosquitos, en una localidad de la región pacífica colombiana. Se instalaron 100 mosquiteros Olyset® en 30 viviendas con la recomendación, basados en una encuesta previa, de lavarlos mensualmente. Cuatro, ocho y doce meses después, se aplicó una encuesta en donde se determinó la aceptación teniendo en cuenta: el porcentaje de mosquiteros Olyset® en uso y la percepción de protección de los habitantes contra las picaduras de los mosquitos. Además, en la primera encuesta se indagó sobre los posibles efectos secundarios en la salud de los usuarios por el uso de estos mosquiteros. Grupos de hembras criadas en laboratorio de Anopheles albimanus Wiedemann y Culex quinquefasciatus Say fueron expuestos a los mosquiteros cada cuatro meses para determinar el efecto letal.

La proporción de mosquiteros Olyset® en uso fue disminuyendo en cada evaluación: 77,5%, 51,1% y 46,6% a los cuatro, ocho y doce meses, respectivamente. La misma tendencia fue observada en la percepción de protección contra la picadura de los mosquitos: 82,7%, 62% y 46%, respectivamente. La mortalidad de A. albimanus fue de 100%, 77,8%, 78,6% y 43,7% y la de C. quinquefasciatus de 100%, 42,3%, 74,1% y 5,7% a los cero, cuatro, ocho y doce meses de uso de los mosquiteros, respectivamente. Sólo un 5% de los usuarios manifestó irritación de la piel en los primeros días de uso de estos mosquiteros. En conclusión, durante el año de seguimiento se evidenció una disminución gradual en la aceptación de los mosquiteros Olyset®. Esto probablemente debido a que la notable reducción del efecto letal de los mosquiteros permitió un aumento en las tasas de picadura de los mosquitos que ocasionó la deserción de varios de los usuarios. Sin embargo, no se puede descartar que otras causas hayan contribuido a la reducción en la aceptación.

The use of bednets is promoted by the National Program of Promotion and Prevention of Diseases Transmitted by Vectors in malaria endemic areas of Colombia. This study estimated the acceptance and retention of long-lasting insecticide-treated nets (Olyset®). The study also measured the efficacy of the bednets after being washed once a month. Thirty dwellings were chosen in the village of Beté (Chocó department) to receive bednets. Interviews were administered in four month intervals to determine the frequency of bednet use and to assess the health outcomes. Among the recipients, nets were readily accepted and used at the beginning. However, usage began to decline: 77.5%, 51.1% and 46.6% after 4, 8 and 12 months of use respectively. In addition, 5% of recipients reported skin irritation after 15 days of continuous use. Anopheles albimanus and Culex quinquefasciatus females were exposed to used bednets every four months to estimate mortality and knock down rates. Bioassays revealed a decrease in efficacy over time. A. albimanus mortality was 77.8%, 78.6% and 43.7% after 4, 8 and 12 months of use, respectively. Mortality for C. quinquefasciatus was variable. A. albimanus mean knock down percent was above 80% at each sampling period. C. quinquefasciatus mean knock down percent was at a similar >80% at the 4 and 8 month sampling times, however, declined to 5.7% after 12 months of use. One year of use and monthly washings of bednets results in significantly less acceptance among recipients and a decrease in efficacy.

Salivary gland proteins of the human malaria vector, Anopheles dirus B (Diptera: Culicidae)

Salivary gland proteins of the human malaria vector, Anopheles dirus B were determined and analyzed. The amount of salivary gland proteins in mosquitoes aged between 3 - 10 days was approximately 1.08 ± 0.04 æg/female and 0.1 ± 0.05 æg/male. The salivary glands of both sexes displayed the same morphological organization as that of other anopheline mosquitoes. In females, apyrase accumulated in the distal regions, whereas alpha-glucosidase was found in the proximal region of the lateral lobes. This differential distribution of the analyzed enzymes reflects specialization of different regions for sugar and blood feeding. SDS-PAGE analysis revealed that at least seven major proteins were found in the female salivary glands, of which each morphological region contained different major proteins. Similar electrophoretic protein profiles were detected comparing unfed and blood-fed mosquitoes, suggesting that there is no specific protein induced by blood. Two-dimensional polyacrylamide gel analysis showed the most abundant salivary gland protein, with a molecular mass of approximately 35 kilodaltons and an isoelectric point of approximately 4.0. These results provide basic information that would lead to further study on the role of salivary proteins of An. dirus B in disease transmission and hematophagy.

Proteínas das glândulas salivares do Anopheles dirus B (Diptera: Culicidae), vetor da malária humana foram determinadas e analisadas. A quantidade de proteínas das glândulas salivares em mosquitos com três a 10 dias de idade foi de aproximadamente 1,08 ± 0,04 æg/ fêmea e de 0,1 ± 0,05 æg/macho. As glândulas salivares de ambos os sexos mostraram organização morfológica semelhante à de outros mosquitos anofelinos. Em fêmeas, apirase acumula-se nas regiões distais, enquanto alfa-glucosidase foi encontrada na região proximal dos lóbulos laterais. Esta distribuição diferencial das enzimas analisadas reflete a especialização de diferentes regiões para alimentação de açucares e sangue. Análise SDS-PAGE revelou que pelo menos sete proteínas foram encontradas nas glândulas salivares de fêmeas, das quais cada região morfológica continha diferentes proteínas principais. Perfis eletroforéticos de proteínas semelhantes foram detectados comparando-se mosquitos não alimentados e alimentados por sangue, sugerindo que não existe proteína específica induzida pelo mesmo. Análise por gel poliacrilamida bi-dimensional mostrou a mais abundante proteína de glândulas salivares com aproximadamente 35 kilodaltons de massa molecular e ponto isoelétrico de aproximadamente 4,0. Estes resultados dão informações básicas que levariam a estudos adicionais sobre o papel das proteínas salivares do An. dirus B na transmissão da doença e hematofagia.