Immunogenicity and Protection against Foot-and-Mouth Disease Virus in Swine Intradermally Vaccinated with a Bivalent Vaccine of Foot-and-Mouth Disease Virus Type O and A

Abstract

Following the worst outbreak of foot-and-mouth disease (FMD), a highly contagious disease in cloven-hoofed animals caused by the FMD virus, from November 2010–April 2011, the Korean government enforced a mandatory vaccination policy. A bivalent (FMD type O and A; O + A) vaccine has been recently implemented. Although the FMD outbreak was suppressed by vaccination, the intramuscular (IM) injection presents side effects. Therefore, improving FMD vaccine quality is necessary. Here, we investigated the side effects and immune efficacy of the O + A bivalent vaccine using two different routes of administration: intradermal (ID) and IM. To compare the immune efficacy of the two inoculation routes, virus neutralization titers and structural protein (antigen) levels were measured. The protective efficacy of ID vaccines was confirmed using two viruses (FMDV O/AS/SKR/2019 and A/GP/SKR/2018) isolated in the Republic of Korea. Serological analysis revealed that both animals administered by ID and IM injections exhibited equal immune efficacy. A virus challenge test in the target animal (swine) revealed no (or extremely low) clinical symptoms. Swine in the ID injected group exhibited no side effects. In conclusion, we suggest that the ID route of vaccination is an effective alternative to the existing IM route, which is associated with more frequent side effects.

Evaluation of a Vaccine Candidate Designed for Broad-Spectrum Protection against Type A Foot-and-Mouth Disease in Asia

“…Although the A/ASIA/G-VII virus has not yet emerged in Korea, it occurs frequently in neighboring countries; thus, there is a significant risk of not only A/ASIA/Sea-97 G1 and A/ASIA/Sea-97 G2 outbreaks in Korea but also A/ASIA/G-VII outbreaks [ 4 ]. For this reason, there is an urgent need to develop new vaccine strains that can provide effective protection against antigenically diverse type A FMDVs [ 7 ].…”

“…The type A FMDV that occurred in 2010 was of the Asia/Sea-97/G1 clade. This was followed by outbreaks in cattle in 2017 and in pigs in 2018 of viruses belonging to the Asia 1/Sea-97/G2 clade [ 4 ].…”