THE USE OF SEQUENCE-ANALYSIS OF A FELINE CALICIVIRUS (FCV) HYPERVARIABLE REGION IN THE EPIDEMIOLOGIC INVESTIGATION OF FCV RELATED DISEASE AND VACCINE FAILURES

A reverse transcriptase polymerase chain reaction (PCR) was used to am plify a 235 bp hypervariable region of the feline calicivirus (FCV) ge nome which encodes part of the capsid protein. Sequence from this regi on was used to compare viruses used in thr-ee attenuated vaccines to v iruses isolated from vaccinated cats with clinical signs of FCV-infect ion (vaccine failures), All three vaccine viruses contained sequence s imilar to that published for FCV strain F9 (Carter et al, 1992, Virolo gy 190, 443-448), However, two of the three vaccines contained a separ ate sequence which was 20.67% distant (number of nucleotide substituti ons pel 100 bases) from F9, The sequences derived from isolates obtain ed from vaccine failures fell into two categories, Most were distinct (21.33-38.00% distant) from vaccine sequence, However, in some cases, sequences were sufficiently similar to the vaccines' (0.00-5.33% dista nt) to suggest that the isolate may have originated from the vaccine. In addition, comparison of sequence determined for isolates from the s ame disease outbreak showed them to be closely related (0.00-1.33% dis tant), whereas epidemiologically unrelated isolates were 20.67-38.00% distant. (C) 1997 Elsevier Science Ltd.