Classical Swine Fever Virus (CSFV) causes CSF, one of the most serious diseases affecting swine. CSFV infection leads to fever, diarrhoea and wasting, with death after around 2 weeks. Live attenuated vaccine, C strain, provides full protection from 5 days post vaccination but does not provide the ability to Differentiate Vaccinated from Infected Animals (DIVA). Subunit vaccines allow DIVA but are less effective. Ideally CSFV vaccines would incorporate the efficacy of C strain but allow DIVA.

Porvac is a promising subunit vaccine, formulated by fusing the CSFV E2 protein with porcine CD154 (CD40L), leading to an improved immune response. Inoculations of Porvac, C strain, E2 control and a Mock were compared in CSFV challenged pigs. DC populations in the lymph and tonsil were compared. All vaccinated animals were protected, and C strain and Mock inoculations showed similar patterns of DC frequency and activation as did both subunit vaccines.

Vaccine efficacy is also dependent on route of inoculation and adjuvant. Porvac is formulated with the mineral oil emulsion adjuvant ISA50V2. The impact of this adjuvant on DC responses was compared to an alternative emulsion adjuvant ISA201VG. A novel inoculation method of implanting solid dose vaccine subcutaneously was also trialled, alongside this solid dose with pathogen associated molecular patterns (PAMPs) injection as an adjuvant. These results showed high reactogenicity with adjuvants but also high immunogenicity.

An unclassified CD163⁺CD14⁺ population had been identified in tonsils of C strain vaccinated, and Alfort infected, but not healthy, animals. This population were highly susceptible to CSFV infection and may play a role in the balance between pathogenicity and protection. In vitro work was carried out to characterise these cells with a focus on generation of an equivalent population from blood derived monocytes. A large population of monocytes became CD163⁺CD14⁺CD16⁺ after culture with their appearance not altered via infection, though they were susceptible to CSFV infection.