Neuraminidase inhibitors are the only class of antiviral drugs currently approved for use against influenza virus infections. They function by binding within the active site of the neuraminidase enzyme on the surface of the virus particle and in doing prevent progeny viruses from being detached from the host cell.
Over the past decade, a growing number of strains resistant to the current antiviral inhibitors oseltamivir and zanamivir have been detected. This has prompted efforts to identify and screen a new generation of neuraminidase inhibitors without the same susceptibilities. Of particular interest, are inhibitors which bind differently within the active site including those which exploit the so-called 430-cavity, a region adjacent to the 150-cavity, targeted by oseltamivir and zanamivir, which contains the majority of known resistance mutations.
Flavonoids are compounds that have been shown promise based on computational studies. Anthocyanidins found as pigments in flowers and fruits, particularly berries, represent one class of flavonoids. Here we demonstrate the ability of a MALDI mass spectrometry based approach we have developed to screen the inhibitory potential of such compounds and establish their mode of binding at a molecular level. We demonstrate the sensitivity and power of the approach for establishing the relative affinity of anthocyanidins with subtly different structures and show that the results are in close accord with those derived from separate neuraminidase inhibition assays.
Importantly, the approach has broad applicability to the study of protein interactions in general and can achieve reasonably high sample throughput where samples are processed in parallel and rapidly analysed by means of the high capacity MALDI sample plate.