The experimental data obtained by immunological, immunomorphological, biochemical, and virological methods are presented which substantiate a concept that various strains of influenza virus under study may penetrate tissue cells at sites of high affinity usually meant for low-density lipoproteins (LDLP) providing the cells with cholesterol for construction of outer and inner membranes. A computer analysis of a bank of data on the primary structure of proteins (the package of GENBER programme) revealed significant similarity of amino acid sequences between the area of viral hemagglutinin site attachment to cells and corresponding amino acids comprising apoB LDLP. The presented proofs are a convincing example of virus particles mimicry realized at the molecular level and give new concepts concerning the mechanisms of virus penetration into body cells which are important for the development of a principally new approach to creation of highly effective antiviral compounds. Moreover, the observed phenomenon may serve for explanation of the nature and mechanism of action of the so-called thermostable virus-neutralizing blood serum inhibitor.