Scientists made a virus‑based vaccine for wild boars that also carries a piece of the hormone GnRH. When boars got the vaccine, they made antibodies against GnRH, which lowered their testosterone and caused some shrinkage and damage to the testes. The vaccine worked both when given by mouth and by injection, though the injection was more effective.

Classical swine fever virus (CSFV) is a highly contagious and fatal disease in pigs and wild boars. While hunting and bait vaccination are effective for CSFV eradication, additional strategies are needed to control wild boar populations. This study aimed to develop an oral vaccine, Flc-LOM-GnRHx3, by inserting gonadotropin-releasing hormone (GnRH) epitopes into the Flc-LOM clone. The Flc-LOM-GnRHx3 strain was rescued from CPK cells and propagated to high titers in MDBK cells. Male boars (20 weeks old) received three doses (10^5.0 TCID₅₀/ml/dose) of Flc-LOM-GnRHx3 either orally or intramuscularly at 2-week intervals. Anti-CSFV E2 antibodies were detected via immunofluorescence and Western blotting. Both vaccination routes induced anti-GnRH antibodies and reduced testosterone levels. Testis size and weight were slightly lower than controls, with seminiferous tubule and spermatid deformities observed in 52.5% of intramuscularly vaccinated pigs and 20.8% of orally vaccinated pigs. Flc-LOM-GnRHx3 demonstrates potential as a dual-function oral vaccine that can eradicate CSFV and impair reproductive capacity in wild boars, offering a novel approach for integrated disease control and population management.