Virus reprogramming of host cellular function is a critical strategy for viral survival and replication. A better understanding of virus-host interaction may provide new potential avenues for the treatment of viral diseases. It has been reported that hypoxia-inducible factor-1 (HIF-1) pathway is activated by a range of pathogens via different mechanisms, but the impact of Influenza A virus on HIF-1 signaling is still unclear. In this study, we observed H1N1 infection stabilized HIF-1α under normoxic conditions. In detail, H1N1 did not increase HIF-1α mRNA transcription, nor impaired posttranslational prolyl hydroxylation or ubiquitination of HIF-1α, but inhibited the function of proteasome, resulting in HIF-1α accumulation. Furthermore, a decreased expression of factor inhibiting HIF-1 (FIH-1), which hydroxylates asparagine 803 within HIF-1α to repress HIF-1α activity, was seen after H1N1 infection. Taken together, these findings reveal a previously unrecognized mechanism of viral activation of the HIF-1 pathway, resembling a hypoxic response in normoxia.

Norovirus (NoV) is now recognized as a leading cause of nonbacterial acute gastroenteritis; however, the NoV GII.17 genotype has rarely been reported as the predominant genotype in clinical diarrhe...

Infection with the influenza A (H1N1) virus is a major challenge for public health because it can cause severe morbidity and even mortality in humans. The over-secretion of inflammatory cytokines (...

Neuraminidase inhibitors (NAIs) are the only available licensed therapeutics against human H7N9 influenza virus infections. The emergence of NAI-resistant variants of H7N9viruses with an NA R292K mutation poses a therapeutic challenge. A comprehensive understanding of the susceptibility of these viruses to clinically available NAIs, non-NAIs and their combinations is crucial for effective treatment. In this study, by using limited serial passage and plaque purification, an R292K variant of the Anhui1 lineage was isolated from a patient with clinical evidence of resistance to oseltamivir. In vitro and cell-based assays confirmed a high level of resistance conferred by the R292K mutation to oseltamivir carboxylate and a moderate level of resistance to zanamivir and peramivir. Non-NAI antivirals, such as T-705, ribavirin and NT-300, efficiently inhibited both the variant and the wild-type in cell-based assays. A combination of NAIs and non-NAIs did not exhibit a marked synergistic effect against the R292K va...

A novel electronic cell sensor array technology, the real-time cell analysis (RTCA) system, was developed to monitor cell events. Unlike the conventional methods labeling the target cells with fluorescence, luminescence, or light absorption, the RTCA system allows for label-free detection of cell processes directly without the incorporation of labels. Here, we used this new format to measure the cytopathic effect (CPE) of the 2009 influenza A (H1N1) virus and the efficacy of neutralizing antibodies in human sera to this virus. The real-time dynamic monitoring of CPE was performed on MDCK cell cultures infected with the H1N1 virus, ranging from 5.50×10² to 5.50×10⁷ copies/mL. The resulting CPE kinetic curves were automatically recorded and were both time and viral load dependent. The CPE kinetics were also distinguishable between different H1N1 stains, as the onset of CPE induced by the A/Shanghai/37T/2009 H1N1 virus was earlier than that of the A/Shanghai/143T/2009 H1N1 virus. Furthermore, inhibition of H1N1 virus-induced CPE in the presence of human specific anti-sera was detected and quantified using the RTCA system. Antibody titers determined using this new neutralization test correlated well with those obtained independently via the standard hemagglutination inhibition test. Taken together, this new CPE assay format provided label-free and high-throughput measurement of viral growth and the effect of neutralizing antibodies, illustrating its potential in influenza vaccine studies.

Serologic studies are urgently needed to assist in understanding an outbreak of influenza A(H7N9) virus. However, a biosafety level 3 laboratory is required for conventional serologic assays with live lethal virus. We describe a safe pseudovirus–based neutralization assay with preliminary assessment using subtype H7N9–infected samples and controls.