The subgroup F adenoviruses.

Background. Introduction. Human subgroup F adenoviruses (Ad) differ from all other adenoviruses in having been discovered by electron microscopy rather than culture (Flewett et al., 1974). Ironically, the first isolate, designated strain Tak, was noted in 1973 as an unidentifiable adenovirus giving CPE in HeLa cells, but remained uncharacterized for several years (de Jong et al., 1983). After more than 20 years, and despite appreciable advances in their genomic characterization, the fastidiousness of subgroup F adenoviruses in culture remains largely unexplained. This has baffled experts in adenovirus diagnosis and strain characterization and continues to intrigue others adopting a more molecular approach to their recalcitrant nature. Subgroup F adenoviruses present a quite different phenotype to that of the prototype human adenovirus (Ad2), which, by its ability to replicate efficiently in human cell cultures, allowed elucidation of eukaryotic splicing mechanisms.