Differentiation of infectious laryngotracheitis virus strains by polymerase chain reaction.

Oligonucleotide primers derived from infectious laryngotracheitis virus (ILTV) DNA clones of vaccine and virulent strains were used to develop a polymerase chain reaction (PCR) for the identification and differentiation of ILTV strains. The PCR followed by restriction endonuclease analysis was used to group four strains of ILTV. A 458-bp sequence that for the LT-IVAX ILTV strain contains a unique BamHI site was amplified by PCR and digested with BamHI restriction endonuclease. From the sizes of the resultant DNA fragments the virulent strain was distinguished from the three low virulence strains.