ACTIVITY OF ANTIBODIES AGAINST SALMONELLA-DUBLIN, TOXOPLASMA-GONDII, OR ACTINOBACILLUS-PLEUROPNEUMONIAE IN SERA AFTER TREATMENT WITH ELECTRON-BEAM IRRADIATION OR BINARY ETHYLENIMINE

Viral contamination of biological material may constitute a risk when samples are exchanged between countries, and it may be necessary to su bject the material to an inactivation treatment. The present study inv estigated possible adverse effects on antibody activity subsequent to either electron beam irradiation or binary ethylenimine (BEI) treatmen t The treatments were performed with sera obtained from pigs or cattle . For each treatment level, the posttreatment activity was plotted aga inst the pretreatment activity and regression analyses were carried ou t. The slope of the regression line was used as an estimate for the re lative posttreatment activity. For a Toxoplasma gondii indirect enzyme -linked immunosorbent assay (ELISA) and agglutination assay as well as for a Salmonella dublin indirect ELISA, the posttreatment activity wa s more than 89% of the pretreatment activity when the samples were irr adiated in the frozen state (on dry ice) with up to 46.5 key or when t hey were treated with 5 or 10 mM BEI for up to 48 h. The samples were more sensitive to irradiation in the liquid state. Thus, samples irrad iated nith 22.6 kGy retained 98% of their activity in the indirect ELI SA when they were irradiated in the frozen state on dry ice but only 3 5% of their activity when they were irradiated in the liquid state at 0 degrees C. The patterns seen in an S. dublin blocking ELISA and an A ctinobacillus pleuropneumoniae complement fixation assay differed in t hat samples with a low level of pretreatment activity were subject to a relatively greater decrease in activity than samples with a high lev el of pretreatment activity. The complement fixation assay was particu larly sensitive to irradiation of serum. ft is concluded that serum sa mples retain sufficient activity by both methods of virus inactivation , especially when used in indirect ELISA or in the T. gondii agglutina tion assay.