Summary of informal discussion of part I of genital herpesvirus.

The discussion concentrated on antigenic aspects of HSV * (structural and nonstructural antigens, type-specific anti gens, antigenic differences among HSV-2 strains, and an tigens common to HSV-2 and cervical cancer) and on anti body responses to HSV (ability to detect specific HSV-2 reactions, role of prior HSV-1 experience, methods of mea surement, and frequency of HSV-2 antibodies in cervical cancer). Dr. Roizman reviewed the relation of antigens to various components of the virus. He presented electron micro graphs indicating that viral DNA is spooled around a cen tral cylindrical body which is surrounded by a protein capsid and by an envelope (2). By acrylamide gel electrophoresis, 24 proteins have been detected (3,7). Four proteins (Pro teins 5, 19, 23, and 24) are present in the empty capsid and two additional proteins (Proteins 21 and 22a) in the full capsid. It is likely that Protein 21 is the protein that makes up the cylinder on which the DNA is wound. Ten proteins (Proteins 7, 8, and 11 to 18) comprise the glycoproteins present in the viral envelope. These glycoproteins are also present in the membranes of infected cells and are contiguous with host proteins in the membranes. These glycoproteins react with neutralizing antibody and can absorb out such antibodies (5). All the envelope glycopro teins of HSV-1 and HSV-2 cross-react with the heterologous sera on immunoabsorbent colums (6). However, Glycoproteins 7 and 8 appeared to have much greater specificity. A macroplaque .HSV mutant which lacks Pro tein 7 or 8 reacts as an intermediate strain. Dr. Roizman predicted that most specific antigens would be nonstruc tural rather than structural proteins, on the basis of his observations that the DNA templates for structural pro teins have more sequences in common than those specify ing nonstructural proteins (4). Dr. Schneweis noted that most fractions obtained from soluble HSV-1 and HSV-2 antigens after cesium chloride ultracentrifugation were common antigens. However, one fraction appeared specific for each HSV type when reacted with homologous antiserum in immunodiffusion tests. Dr. Schneweis also presented results of the typing of 50 HSV isolates by microneutralization tests, showing that all but two strains fell into distinct clusters. Dr. Aurelian noted that, during studies conducted in Yugoslavia, two strains appeared to be different from sev eral American HSV-2 strains, but they still resembled HSV-2 more than HSV-1. She also mentioned an early (4-