| Abstrakt: |
Six-month-old calves were given one injection or two injections 14 days apart, with a vaccine strain of infectious bovine rhinotracheitis (IBR) virus. Six months later the calves received a similar injection. Serum neutralizing antibody titers to IBR virus were determined with and without complement (C′). Nine days after the 1st injection, titers were 16- to 64-fold higher with than without C′. Complement-requiring neutralizing (CRN) antibodies rapidly decreased relative to non-CRN (NCRN) antibodies. Titers 6 months after the 1st injection, although low, were the same or twofold higher with than without C′. An injection of IBR virus at 6 months stimulated the production of NCRN, but not CRN, antibodies. Differences between titers determined with and without C′ of healthy, adult cattle were low. It was concluded that early in the primary response CRN antibodies were preferentially produced compared with NCRN antibodies and, that if this phenomenon occurs in naturally infected cattle, this observation could be useful from a diagnostic point of view. A possible effect of the injection at 14 days in prolonging the CRN antibody response was also observed. |
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