[Immunodepressive action of influenza virus A/PR8/34 on the primary immune response of mice to ram erythocytes].

Influenza A/PR/8/34 virus was shown to suppress markedly the primary immune response of mice to sheep erythrocytes (SE). The suppressive effect of the virus was manifested by a decrease in the number of antibody-forming cells (AFC) in the spleens of the infected animals and was most marked when the mice had been infected two days before the application of the test antigen (SE). When SE and the virus were inoculated simultaneously the decrease in the AFC number was insignificant. Finally, in the group of animals infected two days after injection of the test antigen no inhibition of immune response was observed. It is concluded that the inductive phase of immune response is most vulnerable for influenza virus. In influenza virus-infected mice, visual atrophy of the spleen and a considerable decrease in the number of nucleus-containing cells in the organ were observed.