The use of sequence analysis of a feline calicivirus (FCV) hypervariable region in the epidemiological investigation of FCV related disease and vaccine failures

A reverse transcriptase polymerase chain reaction (PCR) was used to amplify a 235 bp hypervariable region of the feline calicivirus (FCV) genome which encodes part of the capsid protein. Sequence from this region was used to compare viruses used in thr-ee attenuated vaccines to viruses isolated from vaccinated cats with clinical signs of FCV-infection (vaccine failures), All three vaccine viruses contained sequence similar to that published for FCV strain F9 (Carter et al, 1992, Virology 190, 443-448), However, two of the three vaccines contained a separate sequence which was 20.67% distant (number of nucleotide substitutions pel 100 bases) from F9, The sequences derived from isolates obtained 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% distant) to suggest that the isolate may have originated from the vaccine. In addition, comparison of sequence determined for isolates from the same disease outbreak showed them to be closely related (0.00-1.33% distant), whereas epidemiologically unrelated isolates were 20.67-38.00% distant. (C) 1997 Elsevier Science Ltd.