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By using a genomic probe, DNA hybridization for adenovirus type 41 (Ad41) showed equivalent sensitivity with a direct spot method from clinical specimens compared with a more laborious DNA phenol extraction procedure. By using this direct spot preparation method, fecal specimens of 67 patients were examined under code for blind testing for the presence of adenovirus by DNA hybridization by using two Ad41 probes (genomic and cloned BglII-D) and an adenovirus type 2 genomic probe. Identical results were obtained with both of the Ad41 probes. Of the fecal specimens from 42 children with adenovirus gastroenteritis studied prospectively (16 of whom had enteric adenoviruses), 13 specimens (81%) were detected by DNA hybridization with a cloned Ad41 BglII-D probe. There were 14 fecal specimens that were positive by electron microscopy (EM) and culture for nonenteric adenovirus, and 2 specimens were positive by DNA hybridization (87% specificity); these 2 specimens may have been from a mixed enteric adenovirus and nonenteric adenovirus infection. None of 26 specimens from age-matched healthy control patients was positive for adenovirus by EM or DNA hybridization. Our data indicated that DNA hybridization gives highly reproducible results. The direct spot technique is the method of choice for specimen preparation in the diagnostic laboratory, since it requires only the simplest manipulations in specimen preparation. By using DNA hybridization with the BglII D fragment of a cloned enteric Ad41, both adenovirus type 40 and Ad41 were detected directly from fecal specimens, but it was less sensitive than EM following direct ultracentrifugation of specimens. The Bg1II-D Ad41 DNA probe was highly specific for enteric adenoviruses, and DNA hybridization with this probe could be a useful diagnostic test for these fastidious adenoviruses.

Restriction endonuclease analysis was performed on reference strains of each unknown adenovirus subgenus, in comparison with 40 isolates not identified by our routine methods of neutralization with antisera of species 1 to 8. Several uncommon species would not have been identified initially without the assistance of reference laboratories (species 15, 35, and 37). Other species were identified by comparison with published adenovirus DNA restriction endonuclease patterns or from DNA analysis of reference strains (species 31, 40, and 41). Some isolates could not be matched beyond the level of presumptive adenovirus subgenus. Genomic DNA restriction endonuclease analysis of adenoviruses was useful for the identification of adenovirus isolates in a diagnostic virology laboratory. However, accurate interpretation of results will require more extensive DNA restriction endonuclease fragment analysis of a broader range of adenovirus species and genomic variant strains.