Study at the air/water interface of a hepatitis A N-acetylated and C-amidated synthetic peptide (AcVP3(110-121)-NH₂): I. Surface activity and insertion in lipid monolayers

Synthetic peptide vaccines are safer and cheaper than classical ones, but immunoresponse is usually lower. The early interaction of hepatitis A virus (HAV) with cells during the infection and immunological response processes is not as well-known as for other picornavirus. However, it seems that electrostatic interactions have an important role in the fusion of HAV with cell membranes. In order to gain more understanding in these processes, in the present work, we have studied the interactions of AcVP3110, a synthetic HAV peptide, an acetylated amidated derivative of the epitope VP3(110-121), with a neutral phospholipid (dipalmitoyl phosphatidylcholine), an anionic phospholipid (dipalmitoyl phosphatidylglycerol), and a cationic lipid (stearylamine), using a monolayer technique. AcVP3110 showed higher surface activity than the parent peptide, probably owing to its acyl moiety. Studies of the kinetics at constant area of the peptide injected under monolayers of the lipids assayed showed only slight differences depending on the charge of the lipid. On the other hand, when compression isotherms of these lipids on a subphase containing the peptide were performed, major interactions were found for stearylamine monolayers. Owing to the negative net charge of AcVP3110, it is quite clear that electrostatic forces do have a role in the interaction of this synthetic peptide with membranes, as has been seen with complete HAV.