The use of influenza virus labelled with radio-sulpher in studies of the early stages of the interaction of virus with the host cell

Abstract

1. Influenza virus can be labelled with 35S by cultivation in fertile eggs into which radioactive methionine has been introduced.2. When virus labelled with 35S is fractionated by ether treatment the nucleoprotein soluble antigen fraction contains 15 % of the 35S, the haemagglutinin also contains 15%, while the denatured envelope protein contains 70% of the 35S.3. When sulphur-labelled virus is introduced as a primary inoculum in fertile eggs and extracts of the chorioallantoic membrane are made 1–20 % of 35S is recovered as amino-acid, while the remainder is present as non-infective material of particle size similar to that of the original virus.4. It is suggested that on entry into the cell the virus nucleoprotein is hydrolysed with the release of amino-acid and free nucleic acid, while the virus envelope protein and haemagglutinin remain on the cell surface.The authors are indebted to the Medical Research Council for a grant in aid of expenses, and to Messrs. Eli Lilly and Co. for the generous provision of the Spinco centrifuge used in this work. The radioactive methionine was obtained from the Radiochemical centre at Amersham.

The Mammalian Cell-Virus Relationship

“…The concept of Fazekas de St. Groth (17) that attached virus is engulfed or pinocytosed by the host cell (viropexis), although accepted (18,19) in explanation of virus penetration, must be reconsidered in the light of recent findings (20,21). Little is known of the stages immediately following poliovirus attachment to cells, except that most of the attached virus enters an eclipse period (4,22).…”

“…If so, since externally applied ribonuclease was harmless during penetration, it must be assumed that the protein coat releases its RNA content into or through the cell membrane without exposing it to external fluid. It is interesting that Hoyle and Finter (21) have reported that influenza virus infection is initiated when viral nucleoprotein enters the cell, leaving protein envelope and hemagglutinin on the cell surface. These findings suggest a similarity in the role of nucleic acid in penetration by mammalian and bacterial viruses.…”

The Uptake and Development of Vaccinia Virus in Strain L Cells Followed With Labeled Viral Deoxyribonucleic Acid

“…Three i m m a t u r e particles, one of which is partly obscured by a silver grain. Au (30), M, X 85,000.…”

“…Accordingly, the site of release of viral nucleic acid is unknown and its subsequent fate cannot be followed easily. To obviate the difficulty of distinguishing virus and host cell material, animal viruses have been tagged by radioisotopes and the fate of the labeled material ascertained chemically during the virus-host cell interaction (30,46). As a result of such experiments with myxoviruses, it was suggested that initial release of the infecting component of influenza virus may occur at the cell surface (30).…”

Electron Microscopy of Herpes Simplex Virus

“…Dissenting opinions, however, have been voiced. Hoyle and Finter (16) [see also Wecker and Schafer (32)] concluded from an investigation of influenza virus labeled with radioactive sulfur "that on entry into the cell the virus nucleoprotein is hydrolyzed with release of amino-acid and free nucleic acid, while the virus envelope protein and haemagglutinin remain on the cell surface." Subsequently, Zhdanov et al (35) reached a similar conclusion based on autoradiographic studies of Sendai virus.…”