New developments in the molecular epidemiology of adenovirus 8 keratoconjunctivitis.

Four consecutive epidemics of keratoconjunctivitis caused by adenovirus 8 (Ad8) occurred over a 5-year period in Brest, France. A selection of 30 strains isolated during this period was studied by DNA restriction enzyme analysis using nine restriction enzymes. BglI and SacI were the most discriminative enzymes and allowed the recognition of four DNA variants, all different from the prototype strain Trim. Within each of the epidemics, the strains tested could not be distinguished in this analysis. Between strains from different epidemics differences in DNA structure could be detected however. Thus, the Ad8 epidemics of 1983/1984, 1984, 1987, and 1988 appear to have been due to DNA variants Ad8/D7, D8, D9, and D10, respectively. These results demonstrate that the DNA of Ad8 seems to display a considerable variability, comparable to that observed with Ad7 and Ad21. As has been described for Ad7, Ad21 and Ad41, successive DNA variants of Ad8 prevail during one or more years, and are then replaced by other, newly emerging variants sometimes associated with epidemics.