Anti-influenza A virus activity of uridine derivatives of 2-deoxy sugars

Influenza viruses are important pathogens that cause respiratory infections in humans and animals. Apart from vaccinations, antiviral drugs play a significant role in controlling spread of the disease. Influenza A virus contains two membrane glycoproteins on the external part of viral envelope: hemagglutinin (HA) and neuraminidase (NA), which are crucial for productive infection in target cells. In the present work, two derivatives of tunicamycin - uridine derivatives of 2-deoxy sugars (designated IW3 and IW7), which target the glycan processing steps during maturation of viral glycoproteins, were assayed for their ability to inhibit influenza A virus infection in vitro. Using the cytopathic effect (CPE) inhibition assay and viral plaque reduction assay we showed, that both IW3 and IW7 inhibitors exerted significant inhibitory effect on influenza A virus infection in MDCK cells without significant toxicity for the cells. Moreover, tested compounds selectively suppressed viral protein expression in a dose-dependent manner, suggesting that the mechanism of their antiviral activity may be similar to this shown previously for other viruses. We have also excluded the possibility that both inhibitors act at the replication step of virus life cycle. Using real-time PCR assay it was shown that IW3 and IW7 did not change the level of viral RNA in infected MDCK cells after a single round of infection. Therefore, inhibition of influenza A virus infection by uridine derivatives of 2-deoxy sugars, acting as glycosylation inhibitors, is a promising alternative approach for the development of new anti-influenza A therapy.