Immune responses and protection against foot-and-mouth disease virus (FMDV) challenge in swine vaccinated with adenovirus-FMDV constructs

A replication-defective adenovirus 5 encoding foot-and-mouth disease virus (FMDV) capsid and 3C proteinase coding regions (Ad5-FMDV3CWT) was used to v accinate swine. A single inoculation utilizing 1 x 10(8) plaque forming uni ts (pfu) or an inoculation of 1 x 10(8) followed by a boost of 5 x 10(8) pf u Ad5-FMDV3CWT were tested, along with an inoculation and boost using an ad enovirus encoding the FMDV capsid coding region and an inactive form of the 3C proteinase (Ad5-FMDV3CMUT). Sera collected from these animals were exam ined for the presence of FMDV-specific antibodies using immunoprecipitation , neutralization, and ELISA assays specific for IgM. IgG1 and IgG2. Efficac y studios were performed by placing the vaccinated swine in contact with an FMDV-infected swine and monitoring for signs of disease and changes in ser um antibody levels. Ad5-FMDV3CMUT. which is unable to produce FMDV capsid s tructures, did not elicit FMDV-neutralizing antibodies or protect against F MD. Single inoculation with Ad5-FMDV3CWT generated FMDV-specific neutralizi ng antibodies, and reduced clinical signs in challenged swine, but failed t o completely protect the majority of swine from FMD. Swine which received a primary vaccination with Ad5-FMDV3CWT followed by the boost at 4 weeks gen erated high levels of FMDV-neutralizing antibodies resulting in complete pr otection of five of the six swine and limited disease in the remaining anim al. Increased efficacy of the two-dose regimen was associated with heighten ed levels of FMDV-specific IgG1 and IgG2 antibodies. Published by Elsevier Science Ltd.