The Disintegration of Influenza Virus Particles on Entry into the Host Cell. Studies with Virus labelled with Radiophosphorus.

Influenza A virus labelled with radiophosphorus was introduced as a primary inoculum into the allantoic sac of fertile eggs. Virus so introduced enters the cells of the chorio-allantoic membrane, and a study has been made of the chemical state of 32 P present in the membranes 1½ hr. after inoculation. It was found that on entry into the host cell the virus particle disintegrates probably as a result of destruction of its phospholipid. Radiophosphorus derived from the virus phospholipid can be recovered from the infected membranes by extraction with physiological saline in the form of compounds of small molecular weight which are not precipitated by protein precipitants and are not sedimentable at a centrifugal force of 100,000 g . Saline extracts of the infected membranes also contain labelled nucleic acid which appears to be derived from the virus nucleoprotein. A large part of the nucleoprotein phosphorus of the inoculated labelled virus cannot be recovered from the infected membranes by extraction with physiological saline but can be recovered if the cell nuclear material is dissolved in molar sodium chloride. The 32 P in such molar chloride extracts is partly precipitated with the deoxyribonucleoprotein on dilution with water, and is partly present as free nucleic acid. It is suggested that on entry into the host cell the virus particle is broken down, the phospholipid being destroyed and the nucleoprotein disintegrated with the release of free nucleic acid which enters into a close relation with the cell nuclear material.