First Oral Vaccination of Eurasian Wild Boar Against African Swine Fever Virus Genotype II

Figure 1. Titers of antibody against ASFV in wild boar orally vaccinated with Lv17/WB/Rie1 (gray) and wild boar exposed through contact with vaccinated animals (blue). The latter animals were exposed through contact starting from 0 days (animal ID7), 7 days (ID10), and 15 days (ID17) after vaccination. Titers were determined using the indirect immunoperoxidase test.

Figure 2. Average of clinical scores, body temperatures and Ct values from real-time PCR of wild boar orally vaccinated with Lv17/WB/Rie1 (n = 9; dark blue), exposed through contact (VContact, n = 3; light blue), intramuscularly challenged controls inoculated with virulent ASFV Arm07 (n = 4; red) and late in-contact wild boar (n = 2; gray). Averages are shown at different days post-vaccination (dpv), including days post-challenge (dpc). Error bars indicate SD.

Figure 3. Views of thoracic and abdominal cavities from (A) wild boar orally vaccinated with Lv17/WB/Rie1 and (B) intramuscularly challenged control with virulent ASFV Arm07. Hydrothorax, hepatomegaly, and splenomegaly are evident in (B).

Figure 4. Survey view of pericardial sac (I), kidney (II), and mucosal surface of the intestine (III) from (A) wild boar orally vaccinated with Lv17/WB/Rie1 and (B) intramuscularly challenged controls inoculated with virulent ASFV Arm07. (B) Shows hydropericardium (IB), congestive kidney with acute multifocal ranging from petechial to ecchymotic hemorrhages on the cortex surface (IIB), and numerous acute petechiae on the mucosal surface of the colon (IIIB).

Figure 5. ASFV DNA levels (Ct values from real-time PCR) in post-mortem tissues from animals orally vaccinated with Lv17/WB/Rie1 (dark blue), exposed through contact (VContact, light blue), intramuscularly challenged controls inoculated with virulent ASFV Arm07 (red) and late in-contact wild boar (gray).The unique orally vaccinated animal that did not survive the challenge (ID11) gave strongly positive results in several tissues (Ct = 23.32 ± 1.60), similar to the intramuscularly challenged controls.

Figure 6. Comparison of ASFV DNA levels (Ct values from real-time PCR results) in 16 post-mortem tissues with the number of days from last viremia detected until necropsy. The Ct values are inversely related to the level of virus genome.