AN INFECTIOUS RIBONUCLEIC ACID DERIVED FROM INFLUENZA-INFECTED CELLS

Abstract

Cultures of 14-day old chorio-allantoic membranes were inoculated with a massive dose (about 100 EID50 per cell) of mouse adapted Asian strain of influenza A virus, and an aqueous phase free of phenol was obtained as the undiluted ribonucleic acid (RNA) preparation. Phenol extracted material failed to yield any infectious fraction. The infectious component in the RNA preparation showed many properties which differentiate it from the intact virus. When influenza virus was titrated with RNA-ase there was slight inhibition in chick kidney cells. The RNA-ase appears to interfere with the integrity of RNA but does not act on the intact particle or host cells. The infectivity of the RNA preparations are of low magnitude but the efficiency of infection can be increased by use of the proper diluent; the titer increased when infectious RNA was diluted in a double concentration of Eagle''s basal solution. For successful isolation of the infectious component of influenza virus, the infected tissue must be extracted with phenol at the peak of virus production (at the 18th hour) and prolonged incubation results in virus inactivation. Preliminary studies indicate that the protein fraction of the virus confers stability and integrity upon the infectious RNA for a long period of time.