Amantadine hydrochloride specifically blocks the release of virus particles from H7 influenza virus infected cells. This appears to be the direct consequence of an amantadine induced change in the haemagglutinin (HA) to its low pH conformation. The effect is indirect and mediated via interaction of the drug with the M2 protein since mutants altered in this component alone are insensitive to amantadine. The tining of drug action, some 15-20 min after synthesis, and its coincidence with proteolytic cleavage indicates that the modifications to HA occur late during transport but prior to insertion into the plasma membrane. Reversal by mM concentrations of amines and 0.1 /M monensin indicates that amantadine action causes a reduction in intravesicular pH which triggers the conformational change in HA. We conclude, therefore, that the function of MN inhibited by amantadine is involved in counteracting the acidity of vesicular compartments of the exocytic pathway in infected cells and is important in protecting the structural integrity of the acid-sensitive glycoprotein.

Amantadine (1-aminoadamantane hydrochloride) is effective in the prophylaxis and treatment of influenza A infection. In tissue culture this selective, strain-specific antiviral inhibits either the initiation of infection or virus assembly. The basis of these actions is similar and both the haemagglutinin and M2 proteins are implicated suggesting that amantadine interferes with their functions or the interactions between these two virus proteins. Mutations which confer resistance to amantadine are restricted to four amino acids within a hydrophobic sequence of M2 indicating that the primary target of drug action is the membrane-associated portion of this molecule.

On 26 April 2006, the veterinary authorities in the United Kingdom reported that there had been an outbreak of avian influenza type A/H7 among a 35 000-bird housed poultry flock in eastern England, United Kingdom.

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