Tailed viruses have been found in over 140 prokaryote genera representing most branches
of the Bacterial and Archaeal phylogenetic trees. The host specificity of these viruses can
vary widely; some can infect multiple closely related genera, but perhaps more common
(especially in the host family Enterobacteriacea, where the most varieties have been studied)
are viruses that are specific for particular isolates or groups of isolates of closely related
host species.