THE PROBLEMS OF VIROLOGY 11 



This leads to a typical enzymological formulation iu which the functional 

 activity of a protein or of portion of an organized surface is defined in terms 

 of the range of chemically defined substrates that are destroyed or modified. 

 As far as the virus is concerned this is a functional and biological way of 

 describing what are presumably special protein configurations. 



2. The eclipse phase associated with a partial disappearance of infectivity. 

 Currently this is interpreted as meaning the liberation of genetic material 

 from the crust of somatic material that surrounds it in the infective particle. 



The eclipse phase with its indications of somatic and genetic aspects of the 

 virus particle is an intensely biological concept. Its closest analogy is perhaps 

 wath the old concept of the continuity of the germ plasm. 



3. The appearance of soluble antigen in the infected cell, macromolecular 

 material containing protein and nucleic acid, the protein having an immuno- 

 logical structure specific for influenza virus. 



The recognition of soluble antigen by immunological means is a function 

 of mutually reactive pattern in macromolecules. Here both patterns are 

 defined biologically. The nucleic acid is defined as ribonucleic acid by chemical 

 means and in a relatively crude way it may be differentiated from some ribo- 

 nucleic acids by the relative amounts of the different nucleotides composmg 

 it. 



4. Reversible inhibition both of virus multiplication and of accumulation 

 of soluble antigen under the action of RNAase, both suggesting strongly that 

 free RNA plays an essential part in the process of multipUcation. 



The use of RNAase serves essentially to bring the phenomena into relation 

 with other examples of protein sjmthesis. 



5. The genetic phenomena of heterozygosis and recombination, indicating 

 a phase in which the genetic material of two or more infecting particles is free 

 to mix and interact. 



Here we are dealing with experimental results wholly in genetic concepts 

 and it is immaterial whether the genetic determinants are nucleic acid, 

 protein, or something else. 



6. Interference in virtue of which preinoculation of inactive virus can 

 almost completely inhibit the multiplication of active virus subsequently 

 introduced. The details of this phenomenon suggest strongly that a Hmited 

 nmnber of "points of contact" within the cell are specifically blocked and 

 denied to the after-conung infective virus. 



Here interpretation is still problematical, but most attempts make use of 

 ideas basically similar to the interactions of patterned surfaces of macro- 

 molecules. 



7. The key part played by the host cell surface in the emergence of new 

 virus particles and the bearing of this on the morphology of the particles or 

 filaments, and on the phenomenon of phenotypic mixing of serological character. 



