Genetic Characterization of Feline Calicivirus From China Reveals That Amino Acid Mutations at 441-443 in The ORF2 E Region Are Related to Pathogenicity

Abstract We studied the diversity and regularity of FCV variations in two new feline calicivirus (FCV) isolates QD-7 and QD-164. We compared the genomes of these new strains with 39 from the NCBI database including isolates from China, United States, Germany, South Korea, the United Kingdom and Japan. The nucleotide sequence identities ranged from 75-88 % indicating a high degree of variability. These variations were not related to distributions of the virus by time of isolation and geographical location. Cats that were experimentally infected with the new isolate QD-164 showed typical clinical symptoms of sneezing, fever and conjunctivitis and all recovered within 30 days. In contrast, QD-7 infections were asymptomatic and the virus was cleared within 16 days. These results indicate that QD-7 and QD-164 were naturally attenuated strains. NNS mutations that are characteristic of highly virulent strains at positions 441-443 were absent from QD-7 while QD-164 possessed an N at position 442. This indicated that mutations in regions 441-443 may be linked to disease severity.