Dengue (family Flaviridae, genus Flavivirus, DENV) and dengue hemorrhagic fever (DHF) are presently important public health problems in Costa Rica. The primary strategy for disease control is based on reducing population densities of the main mosquito vector Aedes aegypti (L.) (Diptera: Culicidae). This is heavily dependent on use of chemical insecticides, thus the development of resistance is a frequent threat to control program effectiveness. The objective of this study was to determine the levels of insecticide resistance and the metabolic resistance mechanisms involved in two Ae. aegypti strains collected from two provinces (Puntarenas and Limon) in Costa Rica. Bioassays with larvae were performed according to World Health Organization guidelines and resistance in adults was measured through standard bottle assays. The activities of beta-esterases, cytochrome P450 monooxygenases, and glutathione S-transferases (GST), were assayed through synergists and biochemical tests, wherein the threshold criteria for each enzyme was established using the susceptible Rockefeller strain. The results showed higher resistance levels to the organophosphate (OP) temephos and the pyrethroid deltamethrin in larvae. The efficacy of commercial formulations of temephos in controlling Ae. aegypti populations was 100% mortality up to 11 and 12 d posttreatment with daily water replacements in test containers. Temephos and deltamethrin resistance in larvae were associated with high esterase activity, but not to cytochrome P450 monooxygenase or GST activities. Adult mosquitoes were resistant to deltamethrin, and susceptible to bendiocarb, chlorpyrifos, and cypermethrin. Because temephos and deltamethrin resistance are emerging at the studied sites, alternative insecticides should be considered. The insecticides chlorpyrifos and cypermethrin could be good candidates to use as alternatives for Ae. aegypti control.

La captura se realizó en el 2011, durante una etapa intensiva de control. Se determinó el estado de susceptibilidad a insecticidas de la cepa en estudio y se expuso a una CL95 de un aceite de trementina modificado por fotoisomerización y obtenido de Pinus tropicalis. Se obtuvo alta mortalidad larval y pupal en las larvas sobrevivientes de la exposición. Para la variante I se obtuvo un 70 % de inhibición y para la variante II un 68 %. Las hembras sobrevivientes de ambas variantes disminuyeron su fecundidad con respecto al control. No hubo afectación de la fertilidad.

The E1B 55kDa produced by human adenovirus type 5 is a multifunctional protein that participates in the regulation of several steps during the viral replication cycle. Previous studies suggest this protein plays an important role in postranscriptional regulation of viral and cellular gene expression, as it is required for the selective accumulation of maximal levels of viral late mRNA in the cytoplasm of the infected cell; however the molecular mechanisms that are altered or regulated by this protein have not been elucidated. A ribonucleoprotein motif that could implicate the direct interaction of the protein with RNA was initially predicted and tested in vitro , but the interaction with RNA could not be detected in infected cells, suggesting the interaction may be weak or transient. Here it was determined that the E1B 55kDa interacts with RNA in the context of the viral infection in non-transformed human cells, and its contribution to the adenovirus replication cycle was evaluated. Using recombinant adenoviruses with amino acid substitutions or a deletion in the ribonucleoprotein motif the interaction of E1B 55kDa with RNA was found to correlate with timely and efficient viral DNA replication and viral late mRNA accumulation and splicing.

No abstract

Introducción.Los principales mecanismos de resistencia a los insecticidas desarrollados por los insectos incluyen una serie de enzimas detoxificadoras. Se conoce que estos mecanismos pudieran afectar la efectividad en la actividad insecticida de algunos aceites esenciales. Estudiar la implicación de las enzimas detoxificadoras es importante cuando se pretende recomendar un aceite esencial para el control vectorial.Objetivo. Determinar la actividad de las enzimas de acción metabólica en  dos cepas de Ae. aegypti (susceptible y resistente a insecticidas) al ser expuestas a sus respectivas CL90 de un aceite de trementina obtenido de Pinus tropicalis y modificado por fotoisomerización.Resultados. Los valores de actividad de las β-esterasa y MFO oxidasa no variaron en la cepa susceptible; sin embargo, en la cepa resistente ocurrió una disminución de los valores de estas actividades. La actividad de las GST mostró inhibición en la cepa susceptible, mientras que, para la cepa resistente se encontró un ligero incremento.Conclusiones. En este trabajo se pudo demostrar que las enzimas de acción metabólica evaluadas no constituyen un mecanismo de resistencia en las larvas que sobrevivieron a la exposición del aceite de trementina modificado. Este resultado, unido a los efectos biológicos de este aceite, así como su actividad ovicida, larvicida, pupicida y teratogénica, permite recomendar su uso como un método alternativo para el control de Aedes aegypti.