The polymerase chain reaction for the detection of defective interfering canine parvovirus particles

The PCR assay was used to amplify a portion of the genome of virulent and vaccinal canine parvovirus strains and of a vaccinal feline panleukopenia virus strain. A DNA fragment corresponding to the gene that encodes the VP1/VP2 proteins was amplified. The size of the PCR products was 2.2 Kbp except for CPV vaccinal 17-80 strain. The PCR product of 17-80 was 1.1 Kbp leading to the hypothesis of the presence of defective particles. All the restriction enzymes digested the 2.2 Kbp amplified products giving restriction fragments of the expected size whereas Hind III, Hpa II and Pvu II did not digest the PCR fragment of 1.1 Kbp.