The cellular link in the immune response in the dynamics of experimental infection caused by influenza A viruses with various properties

: The development of the cell-mediated element of immunity in mice in the course of experimental influenza caused by the virulent and avirulent (ts-mutant) variants of influenza A virus was compared. The strains under test were also found to differ in their capacity for reproduction in pulmonary tissue, which could be determined for the mutant variant A/PR/8/59/1 (with 5 ts-mutations in genes P2, P3, NP, NA and M) only at an effective dose of 7.5 lg EID50. In mice infected with the initial and ts-variants of influenza A virus the formation of all mechanisms of the cell-mediated and humoral elements of immunity (natural killer activity, antitoxic T-lymphocyte activity, antibody-dependent cellular cytotoxicity, virus-specific antibodies) occurred. The curves showing the dynamics of the formation of cytotoxic mechanisms had a phasic (cyclic) character in all forms of the infectious process under study (lethal, sublethal and poorly reproductive). A dose-dependent effect on the character of the formation of these mechanisms was registered; besides, at the later period of observation (till day 14) the presence of activity was noted when the infectious virus was not detected, which may serve as an additional evidence of the prolonged expression of the viral genome in the body of the host.