Status of insecticide resistance in the dengue vector Aedes aegypti in India: A review.

The study aims to present an overview of the extent of insecticide resistance in the dengue vector Aedes aegypti in India. Published data on insecticide resistance in this species were systematically searched through online databases like PubMed, Google, and Google Scholar. From each study, data were extracted and analyzed to understand the spatial and temporal patterns. Particular emphasis was given to the commonly used insecticides for mosquito control. Forty-three studies met the inclusion criteria, of which 13 had adult bioassay data, 13 larval bioassay data and 17 contained both. Data demonstrated high resistance to DDT and resistance is also widespread against carbamates. There is mounting evidence of increased tolerance to pyrethroids and organophosphorus compounds, viz permethrin, deltamethrin, lambda-cyhalothrin, malathion, and temephos. The emergence of resistance to all the insecticide classes further justifies the need for annual resistance monitoring and to maintain a nationwide database that can provide a reference for formulating effective control strategies.

Nonstructural protein-1 (NS1) of dengue virus type-2 differentially stimulate expressions of matrix metalloproteinases in monocytes: protective effect of paracetamol.

BACKGROUND: Dengue fever is a re-emerging viral disease and affects millions of population worldwide. Monocytes are involved in dengue viral disease, however, their exact role is still not clear. In the present study, we investigated, the effect of NS1 antigen of dengue virus and paracetamol on THP-1 monocytes associated to expressions of matrix metalloproteinases (MMPs) and cytokine release. METHODS: Assessment of cell morphology by bright field microscopy, cell viability by MTT assay, protein estimation by Bradford reagent were done in cells exposed to NS1 antigen in the presence and absence of paracetamol. Cytokines estimations were done by ELISA. Expression profile of matrix metalloproteinase genes was done using real-time PCR and reverse-transcriptase PCR. RESULTS: NS1 exposure of THP-1 monocytes cells, changed their cell morphology and activated them for release of proteins in 24 h. Expressions of MMP-2, MMP-8, MMP-9 and MMP-14 genes were upregulated by NS1 exposure. Further, exposure of NS1 to THP-1 monocytes cells increased expression profile of MMP-10 and MMP-13 genes to a lesser extent. Treatment with paracetamol (1 mg/ml and 2 mg/ml), significantly down-regulated the expression profile of MMP-2, MMP-8, MMP-9 and 14 in dose dependent manner. NS1 exposure also increased the release of cytokines IL-4, IL-6, and IL-10 but decreased the release of TNF-α and IL-15. Interestingly, paracetamol reversed NS1 induced changes in the release of these cytokine in dose dependent manner. CONCLUSION: Monocytes mediated expression of MMPs participates in the development of dengue pathogenesis in the severe cases of disease and paracetamol may have a protective effect in dengue viral disease.