Restriction endonuclease patterns of some European and American isolates of avian infectious laryngotracheitis virus.

Eleven isolates of infectious laryngotracheitis virus (nine European and two American) were compared by restriction endonuclease analysis of their DNA after radiolabeling with 32P. Digestion with KpnI gave identical cleavage patterns for all the European isolates, but the two American viruses (one field and one vaccine) showed some differences from them and from each other. In the case of the American vaccine strain, however, these differences were only minor. After BamHI digestion, only the American field isolate appeared to be different, whereas with HindIII, all 11 isolates were identical.