Development and evaluation of monoclonal antibody-based immune electron microscopy for diagnosis of adenovirus types 40 and 41.

Immune electron microscopy based on monoclonal antibodies was developed and evaluated for diagnosis of adenovirus type 40 and adenovirus type 41 directly from clinical specimens. One adenovirus type 40 monoclonal (5-8) and one adenovirus type 41 monoclonal (5-15) were found to react to high titre with homotypic but not heterotypic antigen. These monoclonals were tested on a coded batch of 20 stools which contained adenovirus type 40 or adenovirus type 41. The results showed that 5/6 adenovirus type 40 and 13/14 adenovirus type 41 strains were correctly serotyped but one strain of each type failed to react with either serum. A wide variation in the numbers of virions bound to positive grids was observed. A further coded batch of 27 specimens, a mixture of subgenus F (i.e. type 40 or 41) or non-subgenus F adenoviruses, was then tested. There was complete serotype concordance with reference results for 16/19 subgenus F strains and all 8 non-subgenus F adenoviruses gave negative results. However, three subgenus F adenoviruses also gave negative results. In conclusion, monoclonal antibody-based immune electron microscopy accurately distinguished adenovirus type 40 from adenovirus type 41 and both viruses from other adenovirus serotypes in clinical specimens and will therefore be useful in the diagnosis of adenovirus gastroenteritis, but some strains may be missed, presumably because of antigenic variation in surface epitopes.