FIG. 6.

Kinetics of the humoral immune responses of rabbits immunized with BoHV-4-A-CMV-IgK-gE2gD-TM (transmembrane) and compared with those of rabbits immunized with BoHV-4-A-CMV-IgK-gE2gD-14 (secreted). (A) Diagram showing the rabbit immunization scheme and blood sample collection. (B and C) Sera collected from rabbits before immunization and after immunization were evaluated for anti-gD (B) and anti-gE2 (C) antibodies by ELISA. Antibodies detected were expressed as the optical density at 504 nm; each value represents the mean response of five rabbits ± the standard error of the mean (*, P < 0.005 as measured by Student's t test or one-way analysis of variance). (D and E) Anti-BoHV-1 (D) and anti-BVDV (E) serum-neutralizing antibodies (SN) as measured by serum neutralization test. SN antibodies were expressed as the reciprocal of the highest dilution of the serum that inhibited the development of virus-induced CPE in MDBK cells. Virus neutralization titers of >2 (log₂) were considered positive. Each value represents the mean response of five rabbits ± the standard error of the mean (*, P < 0.005 as measured by Student's t test or one-way analysis of variance).