[Laboratory procedures in adenoviruses. III. Sensitivity and specificity of serological tests (author's transl)].

84 paired sera from patients with adenoviral infections were tested in neutralization and hemagglutination-inhibition (HI) against the homologous as well as against heterologous virus types of the respective subgroup. Only titer rises are considered as positive reactions. Sera of patients being infected with adenoviruses of subgroup I viruses (52 pairs, types 7, 3, 4, 14) exhibit high rates of positive reactions in the group-specific complementfixation (CF) and in homologous neutralization, lower rates in homologous HI. On the other hand, heterologous reactions are seen more frequently in neutralization than in HI. Patients with type 4 infections often show antibody responses with viruses of subgroup III (types 1, 2, 5, 6). In infections with these virus types, homologous antibody response is seen in approximately half of the cases only; heterologous reactions are observed rarely. Patients with type 8-infections (25 pairs) almost invariably show positive homologous neutralization, while HI or CF tests often fail to show rising titers. These patients, as well as 2 patients with type 19-infection, exhibit a remarcable high rate and range of cross-reactions in neutralization as well as in HI with numerous types if subgroup II and, to a lesser extent, with viruses outside of subgroup II. Although the relatively late appearance of type-specific antibodies (usually between the 10 th and 14 th days after onset of disease) is advantageous for the demonstration of antibody rises, the type-specific diagnosis of adenoviral infections should preferably be performed by isolation and typing of the virus. The heterologous reactions appear to be based on the presence of overlapping intertypic antigenic determinants rather than on an anamnestic antibody response.