Multiplication of Poliovirus Type I in Preparations of Human Leukocytes and Its Inhibition by Interferon

Abstract

A virulent and an attenuated strain of poliovirus type I multiplied in preparations of washed human leukocytes obtained from normal blood donors. In recently established preparations after inoculation of 10² to 10³ TCID₅₀ of poliovirus, no significant viral increase was observed until the 3rd or 4th day, and maximal titers of 10^6.5 to 10⁷ TCID₅₀/ml were not attained until the 7th or 8th day. Virus added on the 3rd or 4th day after preparation resulted in multiplication without this initial long lag period. The concentration of leukocytes in the suspensions appeared to influence viral multiplication, with the optimal range between 3 and 8 million cells/ml. Only a small proportion of the cells in these preparations appeared to be infected and to support growth of poliovirus. Multiplication of poliovirus in leukocytic suspensions was inhibited by preparations of interferon at high dilutions.