CONCLUDING REMARKS: DengueTools was able to make significant advances in methods for understanding and controlling dengue transmission in a range of settings. These will have implications for public health agendas to counteract dengue, including vaccination programmes.
OUTLOOK: Towards the end of the DengueTools project, Zika virus emerged as an unexpected epidemic in the central and southern America. Given the similarities between the dengue and Zika viruses, with vectors in common, some of the DengueTools thinking translated readily into the Zika situation.
METHOD AND RESULTS: The insecticide resistance status of Aedes populations collected from 24 dengue hotspot areas from the period of December 2018 until June 2019 was proactively monitored using the World Health Organization standard protocol for adult and larval susceptibility testing was conducted, together with elucidation of the mechanisms involved in observed resistance. For resistance monitoring, susceptibility to three adulticides (permethrin, deltamethrin, and malathion) was tested, as well as susceptibility to the larvicide, temephos. Data showed significant resistance to both deltamethrin and permethrin (pyrethroid insecticides), and to malathion (organophosphate insecticide) in all sampled Aedes aegypti populations, while variable resistance patterns were found in the sampled Aedes albopictus populations. Temephos resistance was observed when larvae were tested using the diagnostic dosage of 0.012mg/L but not at the operational dosage of 1mg/L for both species.
CONCLUSION: The present study highlights evidence of a potential threat to the effectiveness of insecticides currently used in dengue vector control, and the urgent requirement for insecticide resistance management to be integrated into the National Dengue Control Program.
RESULTS: The dengue fever mouse model was established by intraperitoneal inoculation of dengue virus, New Guinea C strain at 2 × 106 PFU. Daily oral administration of 1000 mg/kg freeze-dried C. papaya leaf juice (FCPLJ) was done starting from day 1 to day 3 post infection. The RNA was extracted from liver tissues harvested on day 4 post infection. The expression levels of 84 genes related to mouse endothelial cell biology were determined by qRT-PCR technique. Dengue virus infection upregulated 15 genes and downregulated two genes in the liver of AG129 mice. The FCPLJ treatment upregulated monocyte chemoattractant protein 1 and downregulated intercellular adhesion molecule 1, integrin beta 3 and fibronectin 1 genes during dengue virus infection. The data showed the potential effect of FCPLJ treatment on the expression profile of endothelial cell biology related genes in the liver of dengue virus infected-AG129 mice. Further proteomic studies are needed to determine the functional roles of the genes affected by FCPLJ treatment.