Induction of immune responses in cattle with a DNA vaccine encoding glycoprotein C of bovine herpesvirus-1

A DNA vaccine expressing glycoprotein C (gC) of bovine herpesvirus-l (BHV-1 ) was evaluated for inducing immunity in bovines. The plasmid encoding gC o f BHV-1 was injected six times intramuscularly or intradermally into calves at monthly intervals. After immunization by both routes neutralizing antib ody and lymphoproliferative responses developed. The responses in the intra dermally immunized calves were better than those in calves immunized intram uscularly. However, the intradermal (i.d.) route was found to be less effic acious when protection against BHV-1 challenge was compared. Following intr anasal BHV-1 challenge, all immunized calves demonstrated a rise in IgG ant ibody titre on day 3, indicating an anamnestic response. The control non-im munized calf developed a neutralizing antibody response on day 7 post-chall enge. The immunized calves showed a slight rise in temperature and mild cli nical symptoms after challenge. The intramuscularly immunized calves showed earlier clearance of challenge virus compared with intradermally immunized calves. These results indicate that DNA immunization with gC could induce neutralizing antibody and lymphoproliferative responses with BHV-1 responsi ve memory B cells in bovines. However, the immunity developed was not suffi cient to protect calves completely from BHV-1 challenge. (C) 2001 Elsevier Science B.V. All rights reserved.