Experimental Dengue 4 Infection Increases the Production of NS1 Protein and Expression of MicroRNAs-15/16 Levels, Triggering an Apoptosis Caspase Induced Pathway

The World Health Organization has estimated an annual occurrence of approximately 392 million dengue virus (DENV) infections in more than 100 countries where the virus is endemic, and this represents a serious threat to humanity. DENV is a serologic group with four distinct serotypes (DENV1, DENV2, DENV3, and DENV4) belonging to the genus Flavivirus, family Flaviviridae. Dengue is the most widespread mosquito-borne disease in the world. The ~10.7 kb DENV genome encodes three structural proteins (capsid [C], pre-membrane [prM], and envelope [E]) and seven non-structural (NS) proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5). The NS1 protein is found both as a membrane-associated dimer and as a secreted, lipid-associated hexamer. Dimeric NS1 is found on membranes both in cellular compartments and on the cell surface. Secreted NS1 (sNS1) is often present in patient serum at very high levels, which correlates with severe dengue symptoms. This study was carried out to find out how the NS1 protein, miRNAs 15 and 16, and apoptosis are related to each other during DENV4 infection in human liver cell line culture. The Huh 7.5 and HepG2 strains were infected with DENV4, and after different times of infection, miRNA-15 and miRNA-16, viral load, NS1 protein, and caspases 3 and 7 were quantified. This study demonstrated that miRNAs 15 and 16 are overexpressed during infection of HepG2 and HuH7.5 cells by DENV4 and have a relationship with NS1 protein expression, VDEN4 viral load, and caspase pathways 3 and 7, thus making these miRNAs interesting targets for markers of injuries during VDEN infection in human hepatocyte cells.