Persistence of dengue virus RNA in dried Aedes aegypti (Diptera: Culicidae) exposed to natural tropical conditions.

Aedes aegypti (L.) is the primary vector of dengue viruses, a group of four serotypic single-stranded RNA viruses. Dengue virus RNA can be readily detected in fresh or dried infected mosquitoes by using reverse transcriptase-polymerase chain reaction (RT-PCR). The current study examined the persistence and limit of dengue virus RNA detection in infected Ae. aegypti killed and exposed to natural ambient tropical conditions of temperature and humidity. Under relatively harsh conditions, dengue RNA retained sufficient integrity to be detected in dried mosquitoes up to 13 wk after exposure to relatively high ambient temperatures (26.3-31.7 degrees C) and relative humidity (49.4-69.9%). These findings confirm that the necessity for testing either fresh or frozen mosquitoes is not a prerequisite when using RT-PCR as the viral detection method, and under particular epidemiological circumstances it allows for a more convenient means of conducting vector-virus surveillance activities where collection methods and logistics may preclude immediate testing or access to a cold chain.

Isolated erythrocyte membranes of transfusion-dependent and non-transfused thalassemia patients in Jakarta, investigated by electron paramagnetic resonance spectroscopy.

Erythrocyte membrane structural parameters were studied in transfusion-dependent beta-thalassemia patients, in long-term transfused patients (regularly transfused < 15 years), and in those who had not yet obtained transfusions. Controls were voluntary students up to 30 years of age without diagnosis or clinical signs of thalassemia. Membranes were isolated and investigated by sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) and electron paramagnetic resonance (EPR) spectroscopy. Data obtained from the thiol-reactive spin label N-ethyl-maleimidoproxyl reveal immobilization of protein environment in erythrocyte membranes from thalassemic patients. SDS-PAGE shows both degradation and aggregation of membrane proteins. Thalassemic erythrocyte membranes exert higher order parameters in the hydrophobic region as determined by 16-doxyl-stearic acid. Rotational correlation times of this spin label increase only in transfused patients. Polarity is higher in membranes of all patients than in controls. In the polar interface, order parameters obtained from 5-doxyl-stearic acid increase in non-transfused and decrease in transfusion-dependent patients as compared with controls. Transfused patients exert increasing membrane order in the hydrophobic region and counter-currently decreasing order in the polar interface indicating loss of membrane integrity along with the loss of fluidity and polarity gradients and the loss the energetic barrier function of the membrane.