The Toll-like receptor adaptor molecule TRIF enhances DNA vaccination against classical swine fever.

To evaluate the effects of the Toll/interleukin-1 receptor domain-containing adaptor-inducing interferon-beta (TRIF) on immune responses induced by DNA vaccines, mice were immunized with the eukaryotic expression plasmid pcDNA/E2 encoding classical swine fever virus (CSFV) E2 alone or in combination with the TRIF genetic adjuvant. Immune responses were examined in immunized mice. Our data demonstrates that co-delivery of the DNA vaccine pcDNA/E2 with the TRIF adjuvant augmented specific humoral and cellular immune responses in a mouse model. Vaccination of pigs confirmed that the pcDNA/E2 in combination with TRIF conferred total protection against lethal challenge with highly virulent CSFV. We conclude that TRIF enhances the effects of the DNA vaccine against CSFV infection and could be used as a potential genetic adjuvant for DNA vaccines in large animal species.