Intracellular cytokine production by dengue virus-specific T cells correlates with subclinical secondary infection.

The pathophysiology of dengue virus infection remains poorly understood, although secondary infection is strongly associated with more severe disease. In the present study, we performed a nested, case-control study comparing the responses of pre-illness peripheral blood mononuclear cells between children who would subsequently develop either subclinical or symptomatic secondary infection 6-11 months after the baseline blood samples were obtained and frozen. We analyzed intracellular cytokine production by CD4(+) and CD8(+) cells in response to stimulation with dengue antigen. We found higher frequencies of dengue virus-specific TNFα, IFNγ-, and IL-2-producing T cells among schoolchildren who subsequently developed subclinical infection, compared with those who developed symptomatic secondary dengue virus infection. Although other studies have correlated immune responses during secondary infection with severity of disease, to our knowledge this is the first study to demonstrate a pre-infection dengue-specific immune response that correlates specifically with a subclinical secondary infection.

Interferon alfacon1 is an inhibitor of SARS-corona virus in cell-based models.

Preliminary data examining interferon alfacon1 treatment of SARS-CoV (severe acute respiratory syndrome-corona virus)-infected patients suggests this therapy is well tolerated and of therapeutic benefit. We report herein that interferon alfacon1, has potent in vitro antiviral activity against SARS-CoV. In a cytopathic effect protection (CPE) assay, interferon alfacon1 inhibited the generation of CPE in a dose-dependent manner with an IC50 of 0.001 microg/ml, a clinically achievable level. Furthermore, interferon alfacon1 also demonstrated significant antiviral activity in yield reduction and plaque reduction assays. The in vitro antiviral activity of interferon alfacon1 against SARS-CoV suggests continued evaluation of interferon alfacon1 as a therapeutic treatment for patients infected with SARS-CoV.