The poxvirus antigens

Serological relatedness of monkeypox, variola, and vaccinia viruses

Closely related human and monkey orthopoxviruses were differentiated by serologic techniques. Antiviral sera were tested by immunodiffusion for reactivity against six different viral antigens prepared from either infected cell cultures or infected chorioallantoic membranes (CAMs) of embryonated eggs. Portions of each antiserum were separately absorbed with heterologous antigens from infected CAMs to remove common reactivity. The absorbed sera formed immunodiffusion precipitates with both types of antigen preparation and revealed specific-character differences that made it possible to classify the viruses as variola, vaccinia, or monkeypox. Cross-complement fixation tests were also used to examine the immunologic reactivities of antisera to detergent-treated, purified preparations of three orthopoxviruses. Only common reactivities were detected by this method, however, and differentiating reactivities were not observed.

The virion and soluble antigen proteins of variola, monkeypox, and vaccinia viruses

The structural proteins in purified preparations of variola, monkeypox, and vaccinia viruses were separated and compared by using a high resolution SDS-polyacrylamide gel electrophoresis system. About 30 proteins were resolved for each virus by autoradiography of longitudinally-sliced gel rods. Although the autoradioelectropherograms of each virus were similar, it was possible to differentiate them by their unique protein pattern in the 30,000 to 40,000 molecular weight region of the gels. A single virion glycoprotein (mol. wt. = 38 X 10(3)) and a virion phosphoprotein (mol. wt. = 12 X 10(3)) were associated with each of the virus preparations. Cross-absorbed monospecific immune sera against variola, monkeypox, and vaccinia virus-infected cells were used in immunodiffusion tests to precipitate radiolabeled, homologous, soluble antigen proteins. The predominant antigen protein associated with each immunospecific precipitate had a molecular weight of approximately 73,000.

Isolation of a herpes simplex virus-specific antigenic fraction which stimulates the production of neutralizing antibody

Infection of mammalian cells with herpes simplex virus (HSV) results in the production of a number of virus-induced soluble antigens. Immunodiffusion analyses of the soluble antigen mixture (SAM) obtained from HSV-infected KB or BHK cells revealed at least six well-defined immunoprecipitin bands. Calcium phosphate chromatography (Brushite) was employed to separate one immunoprecipitin (designated CP-1) from the remaining viral and host antigens. We conclude that CP-1 is a viral-specific antigen because (i) specific antiserum, which had been repeatedly absorbed with uninfected cell extracts or serum components, still retained the capacity to react in gel diffusion with CP-1 antigen; (ii) anti-CP-1 serum reacted in gel diffusion with SAM, yielding one precipitin band in identity with the band formed against human gamma globulin; (iii) the CP-1 fraction stimulated the production of HSV-neutralizing antibody of high capacity. The last observation suggests that fraction CP-1 contains a biologically active structural component of the virus which is associated with the envelope. The CP-1 immunoprecipitin was separated from SAM by an alternative method by using a cyanogen bromide-linked immunosorbent prepared from anti-CP-1 gamma globulin. The observation that the CP-1 antigen isolated from the immunosorbent effectively blocked serum-neutralizing activity provided further evidence that neutralizing antibody was directed against CP-1. Acrylamide gel electrophoresis and immunological experiments suggest that the CP-1 antigen is in part a glycoprotein. The finding that CP-1 contains only one antigenic component of the virus will permit future biological studies to be made with a monoprecipitin antiserum. In addition, the techniques described in this paper represent initial steps in the purification of HSV antigens.