Detection of cross-reacting virus-specific human and animal antibodies

A long series of human and animal viruses possess cross-reacting antigens e .g. adenoviruses, pestiviruses, immune-deficiency viruses and herpesviruses . In many cases, clinical diagnostics of viral zoonoses require use of the same antigen preparations for the detection of antibodies in different anim al species and humans. Staphylococcus A- and Streptococcus G-peroxidase con jugates have been used for the detection of antibodies by biochemists and h istologists since many years. This work describes the adaptation of Fc-spec ific conjugates for the detection of virus-specific human and animal antibo dies using commercial ELISA reagents and IF antigen preparations. Recombina nt HCV, HEV and HIV enzyme immune assays were used throughout. The Epstein- Barr virus antigen was prepared according to standard diagnostic immune-flu orescence procedures. The Fc-fragment binding conjugates (manufactured by Pierce Chemical Company , Rockford, Illinois - Cat. No. 32400 - ImmunoPure Recomb Protein A Peroxid ase Conjugated 1 mg or by Sigma-Aldrich Chemichal Co., Cat. No. P-5164) wer e used for the detection of different species specific IgG molecules. The standardization had to be performed with each commercial reagent indivi dually, using positive and negative collections of human sera. HIV reagents always gave false positive results with human sera using Staphylococcus A protein Conjugates. This was not the case with monkey sera. Sera of C. aeth iops mere shown to contain antibodies to hepatitis E virus (1 of 25), HIV2 (18 of 57), HIV-1+2 (8 of 57). The evaluation of O. D./"cutoff" values indi cated that the presence of HIV 1+2 mixed antibodies were not found in the s era of highest crossreacting antibody titres. It was suggested, that the "m ixed" and "unique" reactivities originate from the cross-reaction with two different simian viruses. The HIV-type specific reactivity was confirmed wi th Western-blot tests. More than 90% of the monkeys were seropositive with Epstein-Barr virus reagents. The geometric mean titre was 1:160 in 10 anima ls titrated. Hepatitis E virus antibodies were found in wild swine (9 of 27) and in dome stic pigs (7 of 25). All 7 domestic pigs seroconverted in the 5th months of life indicating one single epidemiological event introducing the virus int o the farm. Though both wild swine and domestic pigs were seronegative for hog cholera, a few animals were found to carry crossreacting antibodies to human hepatitis C virus. Antibodies were detected in cattle crossreacting w ith Epstein-Barr virus, but these animals were negative for bovine herpesvi rus type 4, and the antibodies were shown to be unrelated to Herpesvirus sa imiri antibodies.