Differentiation of vaccine virus from field isolates of feline panleukopenia virus by polymerase chain reaction and restriction fragment length polymorphism analysis

Abstract

In an attempt to distinguish feline panleukopenia virus (FPLV) live vaccine strains from FPLV field isolates in Japan, we compared restriction fragment length polymorphisms (RFLP) of polymerase chain reaction (PCR)-amplified fragments of live FPLV vaccine strains with those of FPLV Japanese field isolates. On the basis of nucleotide sequence differences between PLI-IV, a live vaccine strain, and FPV-483, a recent field isolate, two restriction enzymes, Dra I and Afa I, were selected for PCR-RFLP analysis of nucleotide (nt) differences at nt 3695 and 4508, respectively. Three live vaccine strains including the PLI-IV strain could be distinguished from the Japanese field isolates by their PCR-RFLP patterns by Afa I, but one live vaccine strain was indistinguishable from the Japanese isolates when Dra I and Afa I were used. The Japanese field isolates were divided into two groups by the profile of PCR-RFLP patterns generated by Dra I and Afa I, suggesting that PCR-RFLP analysis using several enzymes provides a good genetic estimate of strain differentiation. No isolate that shows a Dra I-negative/ Afa I-negative pattern has emerged in Japan, indicating the possibility that the live vaccine viruses with a Dra I-negative/ Afa I-negative pattern, such as the PLI-IV strain, are candidates for use as live FPLV vaccine strain in Japan where they can be genetically distinguished from field strains.