Desheva, J.A., Smolonogina, T.A., Sergeeva, M.V., Rekstin, A.R., Swayne, D., Klimov, A.I., Rudenko, L.G.

Study of biological properties of cold-adapted reassortant strain of influenza virus subtype H7N3

Research Institute of Experimental Medicine, Saint-Petersburg, Russia; Center for Diseases Control and Prevention, Atlanta; Southeast Poultry Research Laboratory, Athens, USA

For the development of live attenuated influenza vaccine (LAIV) against influenza virus strains with pandemic potential, method of classic genetic reassortment of donor of attenuation A/Leningrad/134/17/57 (H2N2) [Len/17] with avian apathogenic influenza viruses of different subtypes was used. Strain with genome formula 6:2, which contains HA and NA genes from avian apathogenic virus A/wild duck/Netherlands/12/00 (H7N3) [N7N3-wt] and 6 other genes from Len/17, was studied. Reassortant strain A/17/wild duck/Netherlands/00/84 (H7N3) [Len17/H7] exhibited ts- and ca- phenotype specific for cold-adapted strains. Reassortant was identical on antigenic profile to parent avian virus H7N3-wt. Like cold-adapted donor strain Len/17, Len17/H7 was attenuated for chickens, whereas wild-type parent strain was lethal in 60% of birds after its intravenous challenge. Reassortant strain Len17/H7 was attenuated during intranasal inoculation of 6 EID50 to white mice, which was confirmed by absence of its isolation from the lungs, actively reproduced on nasal mucosa and stimulated specific systemic and local antibody response.
Zh. Mikrobiol. (Moscow), 2009, No. 1, P. 3136