Background: The quality of a vaccine depends strongly on the effects of the adjuvants applied simultaneously with the antigen in the vaccine. The adjuvants enhance the protective effect of the vaccine against a viral challenge. Conversely, oil-type adjuvants leave oil residue inside the bodies of the injected animals that can produce a local reaction in the muscle. The longterm immunogenicity of mice after vaccination was examined. ISA206 or ISA15 oil adjuvants maintained the best immunity, protective capability, and safety among the oil adjuvants in the experimental group. Objectives: This study screened the adjuvant composites aimed at enhancing foot-andmouth disease (FMD) immunity. The C-type lectin or toll-like receptor (TLR) agonist showed the most improved protection rate. Methods: Experimental vaccines were fabricated by mixing various known oil adjuvants and composites that can act as immunogenic adjuvants (gel, saponin, and other components) and examined the enhancement effect on the vaccine. Results: The water in oil (W/O) and water in oil in water (W/O/W) adjuvants showed better immune effects than the oil in water (O/W) adjuvants, which have a small volume of oil component. The W/O type left the largest amount of oil residue, followed by W/O/W and O/W types. In the mouse model, intramuscular inoculation showed a better protection rate than subcutaneous inoculation. Moreover, the protective effect was particularly weak in the case of inoculation in fatty tissue. The initial immune reaction and persistence of long-term immunity were also confirmed in an immune reaction on pigs. Conclusions: The new experimental vaccine with immunostimulants produces improved immune responses and safety in pigs than general oil-adjuvanted vaccines.

Interferon-gamma (IFNgamma) has been demonstrated to have potent stimulatory effects on parameters of cell-mediated immunity in chickens (11). Protection of neonatal leghorn chickens against infection by invasive salmonellae has been associated with enhanced cell-mediated indices of immunity (5). The present investigation evaluated the effect of recombinant-turkey (rt) IFN-gamma on protection of neonatal leghorn chicks from Salmonella enteritidis (SE) organ invasion after experimental challenge in three experiments. In Expt. 1, intraperitoneal (i.p.) administration of 25 microg rtIFNgamma per chick 30 min prior to per os SE challenge resulted in a 35% reduction (P < 0.01) in SE organ invasion when compared with control (vehicle injected) chicks 24 hr post-SE challenge. However, i.p. administration of 2.5 microg rtIFNy per chick was not efficacious in reducing SE organ invasion. In Expt. 2 and Expt. 3, i.p. administration of 13.75 microg rtIFNgamma per chick 30 min prior to per os SE challenge resulted in significant reductions of 38.4% (P < 0.025) and 31.58% (P < 0.01), respectively, in SE organ invasion as compared with control chicks 24 hr post-SE challenge. Administration of 2.5 or 25 microg rtIFNgamma per chick i.p. had no effect on SE organ invasion in either Expt. 2 or Expt. 3 24 hr post-SE challenge. Additionally, i.p. administration of rtIFNgamma 30 min prior to SE challenge in Expt. 2 and Expt. 3 was not associated with protection against SE organ invasion when organ culture was performed 72 hr postchallenge. Further, the oral administration of 25 microg rtIFNgamma per chick was not efficacious in conferring protection against SE organ invasion at 24 or 72 hr postchallenge when this route of administration was evaluated in Expt. 2. Similarly, the subcutaneous administration of a potential repository injection of 13.75 or 25 microg rtIFNgamma per chick did not protect chicks against SE organ invasion when evaluated 72 hr postchallenge. These data indicate a potential acute immunostimulatory activity of rtIFNgamma in chickens experimentally challenged with SE. Further, these experiments, although preliminary, are suggestive of the potential involvement of IFNgamma in cell-mediated or innate mechanisms of protective immunity against salmonellosis in chickens.

Foot-and-mouth disease (FMD) is an acute epidemic that spreads rapidly among cattle and pigs. In 2014, in Korea, despite enforced vaccination, the type O Southeast Asia (SEA) topotype viruses (Mya-98 lineage) infected mainly cattle and pigs simultaneously, thereby causing enormous damage. If a vaccine that is completely protective against this FMD virus is developed and used, it can become a very important preventive measure in Asia, which is where this type of virus mainly circulates. The SEA topotype has been steadily evolving and transforming into new variations since it became epidemic in Asia. Therefore, it became necessary to develop a new vaccine that could provide protection against the FMD virus strain that was responsible for the 2014–2015 outbreak in Korea. This study aimed to develop a vaccine that would provide complete protection against the SEA topotype FMD virus to control sporadic FMD outbreaks, which occur despite the enforcement of vaccination, and to completely prevent virus shedding, thereby preventing the virus from spreading. The vaccine candidate virus developed in this study showed low pathogenicity and can be distinguished from the wild-type FMD virus strain. The developed vaccine was able to protect mice from SEA and Middle East–South Asia topotype virus strains and induced high titers of antibodies against both virus strains in pigs, thereby confirming the sufficiency of its protective function. In particular, the results of the SEA topotype virus challenge test in pigs revealed that perfect immunity was created in the vaccinated pigs, without virus shedding and viremia.