Phosphorylation of influenza A virus NS1 protein at threonine 49 suppresses its interferon antagonistic activity.

Phosphorylation and dephosphorylation acts as a fundamental molecular switch that alters protein function and thereby regulates many cellular processes. The non-structural protein 1 (NS1) of influenza A virus is an important factor regulating virulence by counteracting cellular immune responses against viral infection. NS1 was shown to be phosphorylated at several sites; however, so far, no function has been conclusively assigned to these post-translational events yet. Here, we show that the newly identified phospho-site threonine 49 of NS1 is differentially phosphorylated in the viral replication cycle. Phosphorylation impairs binding of NS1 to double-stranded RNA and TRIM25 as well as complex formation with RIG-I, thereby switching off its interferon antagonistic activity. Because phosphorylation was shown to occur at later stages of infection, we hypothesize that at this stage other functions of the multifunctional NS1 beyond its interferon-antagonistic activity are needed.

The Anti-Cytokine Storm Activity of Quercetin Zinc and Vitamin C Complex.

Cytokine storm is one of the causative deaths in a patient with severe acute respiratory syndrome. This study aimed at evaluating the prophylaxis effect of quercetin complexes with zinc and buffered ascorbic acid upon cytokine storm induction in mice and identifying the complex's acute toxicity. Mice were randomly divided into three groups: group A, control group, received 0.9% normal saline; group B received 100 mg/kg of the complex one hour before lipopolysaccharide (LPS) administration; and group C received the LPS IP 5 mg/kg. Then, levels of interleukin 1 and interleukin 6 were measured in the serum, and lung and kidney tissues were investigated for any changes that may have happened. Thirty mice were used to investigate the acute toxicity; mice were distributed into six groups: one control group and five treated groups; then several serial dilutions from the complex have been prepared for different concentrations from 5 g/kg to 0.312 g/kg. The animals were observed for 14 days. The LD50 was deduced by the straight-line equation calculated from the dose-response curve. The results in this study showed that group A had no significant tissue change. LPS group C showed tissue damage in the lung and kidney, which significantly prevented by the pretreated complex in group B. Moreover, the complex's acute toxicity value (LD50) was 655 mg/kg. In conclusion, the complex has significantly ameliorated LPS-induced acute lung and kidney injury, largely through suppression of inflammation; the large lethal dose value may make the complex have a promising therapeutic effect in the prevention of cytokine storm.