Various viral agents of the adenovirus group have now been isolated from cases of epidemic keratoconjunctivitis (EKC),1,2 pharyngoconjunctival fever,3 and sporadic forms of catarrhal and follicular conjunctivitis.4
For the identification of adenoviruses a soluble complement-fixing antigen, which is specific for the adenovirus group and common to all its members, is used. Serotypes of the adenovirus group are generally determined by type-specific neutralizing antibody tests with use of rabbit immune sera.3 Eighteen human and five simian serotypes of adenoviruses have now been established by this method.5
Precipitation tests in vitro, using vaccinia virus6 and psittacosis virus7 as antigens and their respective antisera as sources of antibody, have been performed with success, but viruses of smaller size, with the possible exception of influenza virus,8 have thus far not proved so satisfactory for this gross type of reaction. Demonstration of precipitating antibody to viruses of