INCLUSION OF SITE-SPECIFIC MUTATIONS INTO CONSERVATIVE SEG- MENTS OF PA-GENE RESULTS IN ATTENUATION OF VIRULENT INFLUENZA VIRUS STRAIN A/WSN/33.

Aim: Study the possibility of obtaining attenuated variants of influenza virus by including specially selected site-specific mutations into a conservative sequence of PA-gene (terminal segment of COOH-domain of the PA-gene) of a virulent strain.

Materials And Methods: A/ WSN/33 - a virulent strain of influenza virus was used in the study. Inclusion of site-specif- ic mutations into PA-gene of the A/WSN/33 virulent strain was carried out using a two-step mutation PCR.