Immunogenicity for laboratory animals (rabbits and mice) of the whole hepatitis C virus envelope proteins and their conserved as well as hypervariable HVR1 sites has been investigated. Rabbit immune responses to HCV envelope proteins (both single E2 and E1E2 heterodimer) were shown to be much more efficient than murine immune responses. Upon the immunization of the rabbit with E2 protein, antibodies to several highly conserved linear B-epitopes of this protein as well as to the N-terminal fragment of the hypervariable region HVRI were formed. Epitopes in the CR2 region were determined for the first time. Cross-reactivity was revealed between the N-terminal fragment of the protein E2 hypervariable region HVRI and the octapeptide fragment of the protein E1 conserved region CR1, which shared four identical amino acid residues.