Nitric oxide induced by Indian ginseng root extract inhibits Infectious Bursal Disease virus in chicken embryo fibroblasts in vitro

Ganguly, Bhaskar; Umapathi, Vijaypillai; Rastogi, Sunil Kumar

It could be seen that presence of AMG early during infection itself was inhibitory to the virus, suggesting that either AMG is capable of exerting direct effects on the virion or that NO is needed early during infection for the pathogenesis of IBDV in vitro. Indeed, NO is required early during infection by IBDV. NO plays a dual role in the pathogenesis of IBD. Infection by IBDV causes the host to produce NO, which initially helps the virus but later turns detrimental to it. Khatri et al. [19] reported that bursal macrophages were susceptible to IBDV infection and macrophage infection was associated with induction of iNOS. Macrophages from the infected chicken also showed up-regulated cytokine gene expression and increased production of NO. Such activated macrophages inhibit the proliferation of splenocytes in response to mitogenic stimulation. Inhibition of the mitogenic response is likely mediated by NO and this Tcell suppressive activity helps in virus survival. NO attracts and enhances infiltration of inflammatory cells in the bursa, promoting local tissue damage, which initially helps in the spreading of the virus and later helps in clearing the pathogen [18] . In vivo, the infection with virulent IBDV can result in detectable NO levels in serum and the immunosuppressed chicken that fail to induce NO have more severe disease and a higher degree of virus replication [4] .