[Immunization with live attenuated A/H5N1 vaccine protects guinea pigs from reinfection]

Cold-adapted influenza virus A/HK/1/68/162/35(H3N2) was developed as unified donor of attenuation and high reproductive capacity forvaccine strains. The reassortant of this donor with surface antigens of highly pathogenic strain Alchicken/Astana/6/05 (H5N1) was tested in guinea pigs as a live or inactivated preparation. Immunization with both formulations induced equal levels of serum virus specific antibodies, while the level of mucosal antibodies was significantly higher in animals immunized with live virus. The challenge with the homologous virus demonstrated complete virus clearance only in this group, thereby indicating a direct correlation of the protection level with the level of mucosal antibodies.