Live-attenuated foot-and-mouth disease virus vaccine engineered by codon deoptimization induces a strong protective humoral immune response in cattle

Authors: Attreed, Sarah; Silva, Christina; RODRIGUEZ-CALZADA, MONICA - Oak Ridge Institute For Science And Education (ORISE); HEIMROTH, RYAN - Oak Ridge Institute For Science And Education (ORISE); STENFELDT, CAROLINA - Kansas State University; Azzinaro, Paul; Spinard Iii, Edward; Arzt, Jonathan; Rieder, Aida; De Los Santos, Teresa; Medina, Gisselle; MOGULOTHU, AISHWARYA - Oak Ridge Institute For Science And Education (ORISE); MUELLER, STEFFEN - Codagenix, Inc; TAILON, BRUCE - Elanco Animal Health, Inc; DIAZ SAN SEGUNDO, FAYNA - National Institutes Of Health (NIH)

Submitted to: NPJ Vaccines
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/30/2025
Publication Date: 1/24/2026
Citation: Attreed, S.E., Silva, C.M., Rodriguez-Calzada, M., Heimroth, R., Stenfeldt, C., Azzinaro, P.A., Spinard Iii, E.J., Arzt, J., Rieder, A.E., De Los Santos, T.B., Medina, G.N., Mogulothu, A., Mueller, S., Tailon, B., Diaz San Segundo, F. 2026. Live-attenuated foot-and-mouth disease virus vaccine engineered by codon deoptimization induces a strong protective humoral immune response in cattle. NPJ Vaccines. 11. Article 48. https://doi.org/10.1038/s41541-025-01368-7.
DOI: https://doi.org/10.1038/s41541-025-01368-7

Interpretive Summary: Problem: The current commercial foot-and-mouth disease (FMD) vaccine formulation provides limited within- and cross-serotype protection and immunity of limited duration. Novel vaccines are needed that can provide early protection, durable immunity and cross-protection. Accomplishment: Using genetic engineering techniques, we have developed and tested a novel live attenuated FMD vaccine candidate in cattle and found that it: 1) has a broad safety margin, protecting 100% of cattle from infection with FMD virus (FMDV); 2) prevents cattle from shedding viable virus following challenge; and 3) elicits a cross-protective antibody response. Contribution to field: This vaccine has the potential to be applied in FMD outbreak scenarios to help rapidly prevent the spread of this disease.

Technical Abstract: Foot-and-mouth disease (FMD) is a rapidly replicating viral disease with economically devastating effects on livestock production. For 70 years, an inactivated whole antigen vaccine has contributed to control of the disease worldwide. However, recent, rapidly-spreading outbreaks in Europe and Eastern Asia highlight the need for new control strategies that confer early protection and rapidly stop disease spread. Live-attenuated vaccines (LAV) provide strong, early and long-lasting protection against viral diseases; however, possible reversion to virulence must be mitigated. We previously demonstrated that synonymous codon deoptimization of the P1 or P2/P3 coding regions of the viral genome resulted in attenuated FMDV in vitro and in vivo in a mouse model and in swine. Here, an A24Cruzeiro infectious clone with engineered codon deoptimized P2/P3 region (A24-P2/P3Deopt) and DIVA markers was tested for safety and efficacy in Holstein heifers. In the safety study, cattle were intradermolingually (IDL) inoculated with 10^6 or 10^7 pfu A24-P2/P3Deopt. All A24-P2/P3Deopt-inoculated animals remained free of clinical disease, and blood and nasal secretions remained free of viable virus. In the efficacy study, cattle were subcutaneously inoculated/vaccinated either once with 10^5 pfu or twice at 0 and 14 days post-inoculation (dpi) with 10^4, 10^5 or 10^6 pfu A24-P2/P3Deopt. Consistent with the safety study, no animal developed any signs of disease after inoculation. At 28 dpi, all animals were IDL challenged with 10^4 median bovine infectious dose (BID50) of wild-type FMDV A24 All vaccinated animals developed strong neutralizing antibody responses peaking by 28 dpi and all, excepting one animal administered the single dose of 105 pfu, were protected from clinical disease after challenge. Moreover, vaccinated sera show strong cross-reactivity against several A strains and even serotype Asia1. Our work demonstrates that codon deoptimization is a viable technology to derive novel LAV candidates that are safe, immunogenic and efficacious against FMD in cattle.