Co-administration of IL-2 enhances antigen-specific immune responses following vaccination with DNA encoding the glycoprotein E2 of bovine viral diarrhoea virus.

Induction of effective immunity requires the delivery of a protective antigen with appropriate co-stimulatory signals. For bovine viral diarrhoea virus (BVDV) this antigen is the major viral glycoprotein E2. Neutralising antibodies are directed towards the E2 protein and passive transfer of antibodies in serum or colostrum can completely protect against viral infection. DNA vaccination of mice with a construct encoding the E2 glycoprotein induced neutralising antibody levels that were potentially sufficient to prevent virus replication in a challenge system. The co-delivery of interleukin-2 (IL-2) further enhanced the levels of antibody raised. The strong IgG2a component of the antigen-specific antibody suggests a Th1 bias to the immune response induced following vaccination.