Detection of replication competent adenovirus upon serial passaging of recombinant adenovirus expressing FMDV capsid proteins

Generation of Replication Deficient Human Adenovirus 5 (Ad5) Vectored FMD Vaccines

Adenovirus vectors offer a convenient platform for the expression of antigens and have become an attractive system for vaccine development. Currently, the most successful approach to the development of new foot-and-mouth disease (FMD) vaccines has been the production of a replication-defective human serotype 5 adenovirus that delivers the capsid and capsid processing coding regions of FMD virus (FMDV) (Ad5-FMD). A specific construct for FMDV serotype A24 has been fully developed into a commercial product fulfilling the requirements of the Center of Veterinary Biologics (CVB) of the Animal and Plant Health Inspection Service (APHIS) of the U.S. Department of Agriculture (USDA), for commercialization in the USA. In this chapter, we describe a standard protocol for the generation and small-scale production of Ad5-FMDV serotype O1Manisa vaccines. We use directional cloning to introduce the FMDV O1Manisa capsid in the Ad5-Blue vector. This is followed by the linearization of the recombinant Ad5 with Pac I and transfection into HEK293 cells for rescue and propagation, and then by increased production and purification. Finally, purified recombinant virus is characterized by determining virus yield and expression of targeted antigen in specific cell type of interest.

Adenovirus-Vectored Capsid Proteins of the Serotype A Foot-and-Mouth Disease Virus Protect Guinea Pigs Against Challenge

Type A foot-and-mouth disease virus (FMDV) has been detected on China’s pig farms since 2015, and all suspected samples have been strain A/GDMM/CHA/2013. To overcome the shortcomings of inactive FMDV vaccines, we expressed the capsid protein precursor P1-2A and mutated viral 3C protease of FMDV strain A/GDMM/CHA/2013 in a replication-deficient human adenovirus type 5 vector in this study. A significant humoral immune response, T-cell-mediated antiviral response, and mucosa-mediated antiviral response were induced by the adenovirus-vectored FMDV vaccines in BALB/c mice. Immunization of guinea pigs with the adenovirus-vectored FMD vaccines induced significant neutralizing antibodies and anti-FMDV immunoglobulin A antibodies. The recombinant adenovirus rAdv-P12A3C^G38SF48S-GD protected 100% of guinea pigs against challenge when administered intramuscularly. Our study demonstrated the potential utility of rAdv-P12A3C^G38SF48S-GD as a vaccine against type A FMDV.