Early protection against homologous challenge after a single dose of replication-defective human adenovirus type 5 expressing capsid proteins of foot-and-mouth disease virus (FMDV) strain A24.

Previously we demonstrated that two doses of a replication-defective human adenovirus serotype 5 (Ad5) carrying the capsid (P1) and 3C protease coding regions of a laboratory strain of FMDV (A12) completely protected five of six swine challenged with homologous virus. The objective of the current study was to evaluate the efficacy of one dose of an Ad5-vectored vaccine expressing the P1 coding region of an FMDV field strain. A replication-defective Ad5 containing the P1 coding region of FMDV A24 and the 3C coding region of A12 (Ad5A24) was constructed and evaluated for its ability to induce neutralizing antibodies and protect swine against homologous challenge after a single vaccination. Animals were challenged 7, 14 or 42 days after vaccination. Control groups included animals inoculated with commercial vaccine or phosphate-buffered saline. All vaccinated swine were completely protected against homologous challenge at 7, 14 or 42 days after vaccination. Based on these results, we conclude that a single inoculation of Ad5-vectored vaccines could be used as a tool to control FMD in outbreak situations.