Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/17/1996
Publication Date: N/A
Technical Abstract: Little is known concerning the function(s) of specific domains within the single calicivirus capsid protein. The capsid protein of the animal caliciviruses has been divided into 6 distinct regions (A-F). To examine the function of these regions, sequences encoding these domains from the FCV strains CFI, KCD, and NADC were used to replace the homologous sequences in the FCV Urbana infectious clone. With domain swaps of the 33 bp hypervariable E region, distinct differences were noted in growth rate of the recovered viruses when compared to the Urbana parental strain. The NADC E region construct (pUN/E) grew to titers approximately 1 log less than the parental Urbana virus. The KCD E region construct (pUKC/E) grew somewhat better than the Urbana strain approaching titers achieved by the KCD wild-type strain, with complete CPE in 12-16 hours. The CFI E region construct was nonviable. pUN/E produced plaques of 5-6 mm (similar to both hUrbana and NADC) while pUKC/E displayed a small plaque phenotype with plaques of 1-3 mm, a size similar to that of the wild-type KCD virus. Preliminary analysis indicates that E region swaps may also have affected the antigenic characteristics of these viruses. Urbana was neutralized at a dilution of greater than or equal to 512 by homologous antiserum but only at a dilution of 1:8 with NADC antiserum. NADC was neutralized at a dilution of greater than or equal to 512 and less than 1:4 with NADC and Urbana antiserum, respectively. However, pUN/E was neutralized at a dilution of greater than or equal to 512 with anti-NADC and 1:32 with anti- Urbana serum. These data indicate that the E region plays a major role in the antigenicity and neutralization of FCV.