Porvac® Subunit Vaccine E2-CD154 Induces Remarkable Rapid Protection against Classical Swine Fever Virus

Live attenuated C-strain classical swine fever vaccines provide early onset protection. These vaccines confer effective protection against the disease at 5–7 days post-vaccination. It was previously reported that intramuscular administration of the Porvac® vaccine protects against highly virulent classical swine fever virus (CSFV) “Margarita” strain as early as seven days post-vaccination. In order to identify how rapidly protection against CSFV is conferred after a single dose of the Porvac® subunit vaccine E2-CD154, 15 swine, vaccinated with a single dose of Porvac®, were challenged intranasally at five, three, and one day post-vaccination with 2 × 103 LD50 of the highly pathogenic Cuban “Margarita” strain of the classical swine fever virus. Another five animals were the negative control of the experiment. The results provided clinical and virological data confirming protection at five days post-vaccination. Classical swine fever (CSF)-specific IFNγ T cell responses were detected in vaccinated animals but not detected in unvaccinated control animals. These results provided the first data that a subunit protein vaccine demonstrates clinical and viral protection at five days post-vaccination, as modified live vaccines

Porvac^® Subunit Vaccine E2-CD154 Induces Remarkable Rapid Protection against Classical Swine Fever Virus

Live attenuated C-strain classical swine fever vaccines provide early onset protection. These vaccines confer effective protection against the disease at 5–7 days post-vaccination. It was previously reported that intramuscular administration of the Porvac® vaccine protects against highly virulent classical swine fever virus (CSFV) “Margarita” strain as early as seven days post-vaccination. In order to identify how rapidly protection against CSFV is conferred after a single dose of the Porvac® subunit vaccine E2-CD154, 15 swine, vaccinated with a single dose of Porvac®, were challenged intranasally at five, three, and one day post-vaccination with 2 × 103 LD50 of the highly pathogenic Cuban “Margarita” strain of the classical swine fever virus. Another five animals were the negative control of the experiment. The results provided clinical and virological data confirming protection at five days post-vaccination. Classical swine fever (CSF)-specific IFNγ T cell responses were detected in vaccinated animals but not detected in unvaccinated control animals. These results provided the first data that a subunit protein vaccine demonstrates clinical and viral protection at five days post-vaccination, as modified live vaccines

Immunogenicity of E2CD154 Subunit Vaccine Candidate against Classical Swine Fever in Piglets with Different Levels of Maternally Derived Antibodies

E2CD154 is a novel subunit vaccine candidate against classical swine fever virus (CSFV). It contains the E2 envelope protein from CSFV fused to the porcine CD154 molecule formulated in the oil adjuvant MontanideTM ISA50 V2. Previous works evidenced the safety and immunogenicity of this candidate. Here, two other important parameters related to vaccine efficacy were assessed. First, the existence of high maternally derived antibody (MDA) titers in piglets born to sows vaccinated with E2CD154 was demonstrated. These MDA titers remained above 1:200 during the first seven weeks of life. To assess whether the titers interfere with active vaccination, 79 piglets from sows immunized with either E2CD154 or a modified live vaccine were vaccinated with E2CD154 following a 0–21-day biphasic schedule. Animals immunized at either 15, 21, or 33 days of age responded to vaccination by eliciting protective neutralizing antibody (NAb) titers higher than 1:600, with a geometric mean of 1:4335, one week after the booster. Those protective levels of NAb were sustained up to six months of age. No vaccination-related adverse effects were described. As a conclusion, E2CD154 is able to induce protective NAb in piglets with different MDA levels and at different days of age