Development and preliminary evaluation of an enzyme immunosorbent assay for the detection of adenovirus type 8

Epidemic keratoconjunctivitis (EKC) is a highly contagious adenoviral ocular infection which can occur in outbreaks and is predominantly caused by adenovirus type 8 (Ad8). Detection and typing of this virus after isolation is generally by serum neutralisation or more complex molecular techniques. These methods can be time consuming particularly during outbreaks. Therefore, an Ad8 specific antigen capture enzyme immunosorbent assay (EIA) was developed as a rapid and cost effective diagnostic method for laboratories. An Ad8 type-specific monoclonal antibody was used in a direct antigen capture method and an anti-hapten fluorescein isothiocyanate (FITC)-anti-FITC system. Assay configuration studies indicate that the system in which a type specific capture antibody and a group specific detector antibody are used provides greater sensitivity to the assay than a system using a group specific monoclonal or polyclonal capture antibody. Also, this allows the use of the same detector antibody with varying type specific capture antibodies on the solid phase. In a preliminary evaluation of the two formats, the direct antigen capture assay and the FITC-anti-FITC system had a sensitivity of 98.75% and 100%, respectively, with a specificity of 100%. However, these results are not statistically significant due to the low numbers of Ad8 and other viral isolates obtained from eye swabs. The direct EIA format has been shown to be able to detect different Ad8 genome types including four isolated from four epidemics of EKC in Brest, France, the Ad8 prototype strain, and some DNA-variant isolates which had not been typed by restriction endonuclease analysis (REA).