INCLUSION OF SITE-SPECIFIC MUTATIONS INTO CONSERVATIVE SEGMENTS OF РА-GENE RESULTS IN ATTENUATION OF VIRULENT INFLUENZA VIRUS STRAIN A/WSN/33

Abstract

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. А/ WSN/33 - a virulent strain of influenza virus was used in the study. I nclusion of site-specific mutations into PA-gene of the A/WSN/33 virulent strain was carried out using a two-step mutation PCR. Cloning was carried out using GoldenGate reaction. 8-plasmid transfection system based on pHW2000 vector was used. Transformation was carried out in rubidium competent bacterial cells of DH5a strain. Transfection was done using Lipofectamine LTX (Invitrogen) reagent in a 293T and MDCK cells’ co-culture. Results. Transfectants with F658A substitution in the COOH-domain of the PA-gene were shown to acquire ts-phenotype and sharply reduce the ability to reproduce in mice lungs. Introduction of F658A substitution into COOH-domain of the PA-gene in combination with introduction of ts-mutations from ca influenza virus strains into the genome of the virulent strain resulted in obtaining transfectants that have phenotypic characteristics typical for live influenza vaccine candidates. Conclusion. The ability to obtain attenuated variants of influenza viruses by introducing specially selected site-specific mutations into conservative sequence of the PA-gene is shown.