Live Attenuated Potentially Pandemic H5 Vaccines on Cold-adapted A/Leningrad/134/17/57 Master Donor Virus Backbone

The XXI century saw the introduction and spread of emerging potentially pandemic dangerous
infectious diseases, such as novel coronaviruses and a number of avian influenza viruses. 20 years
ago, the first laboratory-confirmed case of human infection with an avian influenza H5N1 was
recognized. The wide enzootic spread of highly pathogenic H5N1 virus among wild and domestic
poultry and a number of severe human respiratory diseases caused by the H5N1 virus have
stimulated the urgent necessity of development of potentially pandemic influenza vaccines.
Live, attenuated cold-adapted reassortant influenza vaccine (LAIV) is considered by World
Health Organization as one of the most promising preparations for preventing pandemics. LAIV has
proven to be safe and efficacious; pandemic LAIV might be more effective than an inactivated
vaccine in providing a broader immune response. This chapter described the development of
LAIVs against potential pandemic H5N1 subtype avian influenza viruses based on Russian
cold-adapted master donor virus, A/Leningrad/134/17/57 (H2N2), and their preclinical and clinical
studies.