Amphipathic alpha-helices and putative cholesterol binding domains of the influenza virus matrix M1 protein are crucial for virion structure organisation.

The influenza virus matrix M1 protein is an amphitropic membrane-associated protein, forming the matrix layer immediately beneath the virus raft membrane, thereby ensuring the proper structure of the influenza virion. The objective of this study was to elucidate M1 fine structural characteristics, which determine amphitropic properties and raft membrane activities of the protein, via 3D in silico modelling with subsequent mutational analysis. Computer simulations suggest the amphipathic nature of the M1 α-helices and the existence of putative cholesterol binding (CRAC) motifs on six amphipathic α-helices.

Evaluation of properties of chitosan as an adjuvant for inactivated influenza vaccines administered parenterally.

Studies on mice showed that chitosan as an adjuvant for H5 inactivated influenza vaccines administered intramuscularly enhances significantly antibody titers and protective efficiency not only against homologous influenza viruses, but also against drift variants. Chitosan adjuvanted vaccines induced high antibody titers after a single immunization and with a low dose of antigen. High antibody titers remained for at least 6 months.