Study tests oral levamisole to boost FMD vaccination in swine
Bottom line
Researchers in South Korea reported that oral levamisole, given separately from a standard intramuscular foot-and-mouth disease, or FMD, vaccine, improved immune responses in both mice and swine. In the new Frontiers in Veterinary Science study, the adjunct was administered orally while the bivalent inactivated vaccine remained unchanged and was delivered by deep intramuscular injection, a setup the authors describe as “route-decoupled.” In pigs, the levamisole group showed higher structural protein antibody and virus-neutralizing titers through 84 days post-vaccination, along with higher IgG and IgA at day 56, compared with pigs that received the same vaccine without levamisole. In mice, the adjunct group also had stronger antibody responses and better post-challenge survival. (frontiersin.org)
Why it matters: For veterinary professionals, the practical appeal is that this approach aims to boost FMD vaccine performance without reformulating the licensed vaccine itself. That could matter in swine programs, where adjuvant choice, injection route, and injection-site reactions have long been important operational issues. WOAH materials note that oil-adjuvanted inactivated vaccines can cause inflammatory local reactions in pigs, and prior literature has highlighted the need for strategies that improve protection while minimizing tissue damage and preserving flexibility in how vaccines are deployed. This study doesn’t establish field efficacy or change policy, but it adds early evidence that an orally delivered immunomodulator might enhance humoral responses while leaving the injected product unchanged. (woah.org)
What to watch: The next question is whether larger pig studies, challenge data in target species, safety assessments, and eventual regulatory development can show that oral levamisole delivers meaningful field-level benefit beyond improved lab readouts. (frontiersin.org)
Key facts
- Study type
- Two-species evaluation in mice and swine
- Journal
- Frontiers in Veterinary Science
- Intervention
- Oral levamisole as a route-decoupled adjunct
- Vaccine
- Standard bivalent inactivated FMD vaccine
- Administration route
- Deep intramuscular injection in the neck
- Pig dose
- 1 mg levamisole per pig
- Pig age
- 8 to 9 weeks
- Key finding in pigs
- Higher structural protein antibody and virus-neutralizing titers through 84 days post-vaccination
- Mouse finding
- Stronger antibody responses and complete survival after viral challenge
A newly published two-species study suggests oral levamisole could serve as a practical add-on to intramuscular FMD vaccination, potentially improving immune responses without requiring manufacturers to alter the vaccine formulation itself. The paper, published in Frontiers in Veterinary Science in 2026, evaluated the approach in mice and FMD-seronegative swine using a conventional bivalent inactivated vaccine and found stronger antibody and neutralizing responses when oral levamisole was used as a separate adjunct. (frontiersin.org)
That framing matters because FMD control still relies heavily on inactivated vaccines, and improving performance without reopening formulation work would be attractive for outbreak response and routine control programs. WOAH describes FMD as a severe, highly contagious livestock disease with major economic consequences, and notes that vaccine potency, safety, and strain matching remain central to control. At the same time, prior reviews of FMD vaccination in pigs have pointed to persistent challenges around durability of protection, adjuvant optimization, and injection-site damage, especially with oil-adjuvanted products. (woah.org)
In the new study, pigs 8 to 9 weeks of age received a standard one-dose bivalent FMD vaccine by deep intramuscular injection in the neck, with or without 1 mg of levamisole per pig. Vaccination was repeated at a 28-day interval, and sera were collected through 84 days post-vaccination. According to the study, pigs in the levamisole group had significantly higher structural protein antibody titers and virus-neutralizing titers against both type O and type A strains at multiple time points, and they also showed higher IgG and IgA concentrations at day 56. In mice, the levamisole adjunct improved antibody responses and was associated with complete survival after viral challenge, compared with lower survival in the vaccine-only control group. (frontiersin.org)
The work also builds on the same research group’s earlier levamisole-adjuvant findings. A 2024 Frontiers in Microbiology paper from the group tested levamisole incorporated into an FMD vaccine formulation and reported enhanced innate and adaptive immune responses in mice and pigs. The new study appears to extend that concept by separating the immunomodulator from the injected product and delivering it orally instead, which is the main operational distinction and the source of its “route-decoupled” framing. That’s an important nuance, because it suggests the authors are looking for a way to strengthen vaccine response without changing the base vaccine composition. (frontiersin.org)
Outside commentary specific to this new paper was limited in publicly accessible sources, but the broader literature supports why the idea is getting attention. Reviews of swine vaccine adjuvants list levamisole among candidate immunostimulants, and older experimental work has described adjuvant effects for levamisole in killed viral vaccines and mucosal vaccination models in pigs. Separately, WOAH and other technical sources continue to emphasize that inactivated and oil-adjuvanted vaccines can produce local inflammatory reactions, granulomas, fibrosis, or abscessation, making any strategy that could improve efficacy without intensifying injection-site burden worth watching. (sciencedirect.com)
Why it matters: For veterinary professionals, especially those working in food animal medicine, the study points to a possible middle path between accepting current vaccine performance and undertaking full reformulation. If an oral adjunct can reliably raise neutralizing responses in pigs while preserving the same intramuscular product, that could eventually offer more flexibility for manufacturers, regulators, and vaccination programs. It may also be relevant in systems where injection-site lesions, carcass quality concerns, or repeated booster logistics already complicate FMD vaccination strategy. Still, this is an early-stage research signal, not a practice recommendation. The study measured immunologic and mouse challenge outcomes, but it does not by itself establish commercial-scale effectiveness, outbreak performance, or regulatory readiness in swine. (frontiersin.org)
What to watch: The key next steps are larger controlled swine studies, target-species challenge data, clearer safety and dosing data for oral administration, and any movement toward product development or regulatory filing. In the U.S., APHIS policy documents underscore that FMD vaccine use sits within a tightly managed preparedness framework, so any adjunct strategy would need a strong evidence package before it could influence control planning. (aphis.usda.gov)