Evidence from NMR study has shown that it binds to the stem
loop region in H7 HA and stabilizes the neutral pH conformation61.
Several anti-influenza A virus compounds with a similar
mechanism were found later. Most of the compounds in this class
were subtype-dependent with a low resistance barrier, and underwent
no further investigation60,62–65. One exception is arbidol
(ARB), currently an approved drug in Russia and China to treat
influenza virus infection (Fig. 5)
66,67. Aribidol was shown to
stabilize the HA by a 0.2 pH unit reduction at the transition
phase66. Recent studies pointed out that both the binding of the
ARB to the polar head groups of phospholipids in the cell
membrane and the presence of the aromatic residues of the viral
surface proteins could contribute to its antivirus activity67. A better
understanding the details of the drug binding mode and resulting
effects on hemagglutinin and lipid interaction would help to design
new ARB-like molecules.