The effect of strain differences on the assay of rabies virus glycoprotein by single radial immunodiffusion.

Antigenic differences between rabies virus strains used for vaccine manufacture can be demonstrated using monoclonal antibodies. We have shown that these differences are sufficiently large to affect the potency values of vaccines measured in single radial immunodiffusion (SRD) assays if the reference and test vaccines are antigenically heterologous. The production of reagents for use in SRD assays for each strain of rabies virus should be considered.

Evaluation of the single radial-immunodiffusion assay for measuring the glycoprotein content of rabies vaccines.

The glycoprotein content of rabies vaccines containing the Pitman-Moore strain of rabies virus was measured by the single radial immunodiffusion assay and correlated with vaccine potency. The variability of this assay was 6.3% for a single vaccine lot tested over a one-year period.

Use of the single radial immunodiffusion test as a replacement for the NIH mouse potency test for rabies vaccine.

The method currently recommended by the World Health Organization (WHO) for the potency assay of rabies vaccine is the NIH mouse potency test, a highly variable test requiring large numbers of animals. The Single Radial Immunodiffusion (SRID) test, an in vitro test, has been used successfully for the quantitation of hemagglutinin in inactivated influenza vaccine and is being evaluated for its utility as an assay for the rabies virus glycoprotein, considered to be the major protective antigen, of rabies vaccine. Potency values calculated using the SRID test were compared with those calculated using the NIH test for rabies vaccines produced in cell culture.

Enhancement of carcinoembryonic antigen expression by interferon.

Human interferon decreased DNA but not RNA synthesis in a human colon carcinoma cell line, WiDr; in addition, there was a two- to three-fold increase in the expression of a tumor-associated antigen, carcinoembryonic antigen. In contrast, interferon had no effect on a normal human diploid cell line, WI-38. Thus, in addition to its anti-cellular effect against tumor cells, interferon can also modulate tumor antigenicity.