[Effect of the host's body genotype and phenotype on the manifestation of the pathogenic properties of the influenza virus].

The sensitivity of mice of CBA (H-2k haplotype), C57BL/6 (H-2b haplotype) strains and their hybrids M1 and F2 to the pathogenic influenza A/PR8/34 (H0N1) and nonpathogenic A/Krasnodar/101/59 (H2N2) virus strains was studied. The lethality, virus replication in the lungs, and the thymic index were determined. An increase in the resistance to the pathogenic influenza virus was found in male C57BL/6 and male F1 (CBA X C57BL/6) hybrids in the summer period as compared with winter. Replication of the pathogenic virus in the lungs of mice, in contrast to the nonpathogenic one, was accompanied by marked atrophy of the thymus. The study suggests the existence of a certain association between the resistance to influenza infection and phenotypic changes in the host connected with the weight of the thymus and the presence of mature T-lymphocytes.