Nitric oxide radical suppresses replication of wild‐type dengue 2 viruses in vitro

Abstract

Nitric oxide is well accepted as one of the defenses for inhibiting viral dissemination. Macrophages and cells in the macrophage lineage are professional nitric oxide producers which sub-serve as target for dengue virus. The interaction between nitric oxide and dengue virus in such target cell is unknown. In this report, the impact of nitric oxide on infectious dengue virus serotype 2 production and RNA replication was investigated in vitro. Primary isolates of dengue virus serotype 2 from dengue patients were replicated in mouse neuroblastoma cells in the presence of an exogenous nitric oxide donor, s-nitroso-N-acethylpennicillamine, SNAP, at the concentration of 50 or 75 or 100 microM. Nitric oxide inhibited viral replication in a dose and a multiplicity of infection dependent manner. Nitric oxide from 50 and 75 microM SNAP delayed and suppressed replication of dengue virus isolates while higher concentration of nitric oxide, 100 microM SNAP, completely inhibited production of infectious particles up to 36 hr study. Twenty-four out of forty tested isolates, 60%, were susceptible to 50 microM SNAP inhibitory effect. The mechanism of inhibition was investigated at the level of RNA synthesis and was found that RNA production was suppressed which correlated to production of the infectious particles. Down-regulation of the RNA synthesis resulted in reduction of protein synthesis which was detected by lower level of NS1 protein synthesis using immunoblotting. In conclusion, nitric oxide from exogenous nitric oxide donor down regulated replication of dengue virus serotype 2 isolates from dengue patients. The suppression was clearly shown at the level of viral RNA and protein synthesis resulting in reduction of viral progenies production. This phenomenon implies that nitric oxide may serve as a defense which diminishes viral load in patients.

Cytokine and nitric oxide production by mouse macrophages infected with brazilian flaviviruses

“…High levels of NO have been shown to play a role in antiviral defense, in particular against several Poxviridae, herpes simplex virus type 1 9,24 . NO may serve as one of the mediators controlling viral load during natural dengue virus infection 6,30 . Mortality was significantly increased in JEV-infected mice treated in vivo with L-NMMA, that reduces NO production.…”

Recent Advances in Deciphering Viral and Host Determinants of Dengue Virus Replication and Pathogenesis

“…IFN-␥-activated macrophages may play an important role in viral clearance, in part through production of nitric oxide (NO), which has recently been demonstrated to inhibit the replication of DENV in vitro (24). Inducible nitric oxide synthase expression in peripheral blood monocytes of DF patients was found to correlate with the late acute phase of disease and preceded the clearance of DENV from monocytes in these patients (141).…”

“…Given the evidence of increased TNF-␣ in DF/DHF patients (18,23,27,84) and the combined evidence of in vitro and animal studies, TNF-␣ is strongly implicated in the pathogenesis of DENV. (22,52) and NO (24,141) are produced primarily by infected monocytes/macrophages and activate endothelial cells, which can contribute to increased vascular permeability (reviewed in reference 17). Changes in vascular permeability in DENV infections have classically been measured by monitoring levels of albumin in the plasma (195).…”

Inhibition of dengue virus replication by mycophenolic acid and ribavirin

“…of 10 and incubated for 72 h with 1 % fetal bovine serum. The plaque assay was performed essentially as described previously (Charnsilpa et al, 2005).To quantify the virus-associated RNA, qRT-PCR was used as described previously (Houng et al, 2000). The detection of PCR product was correlated with input cDNA copy number at various concentrations of antiviral compounds and the results were plotted.…”

“…Therefore, inhibition of IMPDH is expected to inhibit not only proliferation of eukaryotic cells, but also replication of DNA and RNA viruses (Markland et al, 2000). However, RBV, a nucleoside analogue, is a competitive inhibitor of IMPDH.It is approved as an inhaled drug for treatment of respiratory syncytial virus infection, as well as orally, together with alpha interferon, for treatment of hepatitis C virus (HCV) infections.DEN2 was propagated in mosquito (C6/36) cells as described previously (Charnsilpa et al, 2005). LLC-MK2 cells were infected with DEN2 under single-step growth conditions (Dulbecco & Vogt, 1954) at an m.o.i.…”