Summary
Several preparations of fluorescein isothiocyanate-conjugated rabbit antibodies to guinea pig or human γ-globulin fractions were found to be capable of staining the characteristic mumps virus inclusions in infected HeLa cells previously sensitized with virus-specific antibodies derived from heterologous animal species. Brilliant immunofluorescence was elicited by labeled antibodies to heterologous γ-globulins only when the antiviral sera used for the primary stage of the reaction were used undiluted, or at the most in 10-fold dilution. The rabbit anti-guinea pig γ-globulin sera from which effective fluorescein conjugates were prepared yielded from one to three lines of precipitation in Ouchterlony tests with sera from several heterologous species with the exception of rabbits, whereas those sera from which strictly species-specific conjugates were obtained produced no precipitates with heterologous sera. Cross-reacting antisera to guinea pig γ-globulin also reduced the viral neutralizing capacity of human poliomyelitis convalescent serum. No attempts were made to identify the cross-reacting serum component(s). Such broadly reactive anti-γ-globulins might be useful for the indirect technique of immunofluorescence in that they overcome the usually observed species limitation of this method.
