• Vaccine Name: Plant Produced AHSV Serotype 5 VLPs Vaccine
• Target Pathogen: African horse sickness virus
• Type: Subunit vaccine
• Status: Research
• Host Species for Licensed Use: None
• Antigen: Plant-produced AHSV-1/5 VLPs displaying VP2 and VP5 of serotype 5 as the outer shell lay- ered on the AHSV serotype 1 core (VP3/VP7) (O'Kennedy et al., 2022)
• VP2 gene engineering:
  • Type: Recombinant protein preparation
  • Description:
  • Detailed Gene Information: Click Here.
• VP7 gene engineering:
  • Type: Recombinant protein preparation
  • Description:
  • Detailed Gene Information: Click Here.
• Preparation: AHSV-1/5 VLPs were produced in N. benthamiana 𝚫XT/FT. The AHSV virion is a triple layered particle formed by the outer capsids (VP2 and VP5), the middle layer (VP7), and the inner shell (VP3, subcore). D-(+)-Trehalose dihydrate (Sigma-Aldrich)(5 % m/v) was added to the TFF purified VLPs before filter sterilization with a 0.45 lM + 0.2 lM Sartopore 2 sterile capsule (Sartorius, 5441307H4) using a peristaltic pump. The appropriate filter sterilized VLPs were mixed with autoclaved adjuvant (5% Montanide GEL 01 PR, Seppic, France) immediately before vaccination. (O'Kennedy et al., 2022)
• Immunization Route: Intraperitoneal injection (i.p.)
• Description: A plant-produced AHSV-1/5 VLP (Chimaeric Virus-Like Particles) provides protection against AHSV-5 in IFNAR -/- mice. (O'Kennedy et al., 2022)

Mouse Response

• Vaccination Protocol: Eight groups of IFNAR-/- mice (n = 3) were vaccinated intraperitoneally with 1 µg, 5 µg or 10 µg plant-produced VLPs or VP2. Five groups of mice (n = 6 for vaccinated; and n = 3 for control groups) were used in the challenge study. Mice in the challenge study, were prime boost vaccinated (days 0 and 14) with either 10 µg VLPs (group 1) or 10 µg VP2 (group 2) or PBS buffer (negative control, group 3) or BEI inactivated 5x10^4 PFU (positive control, group 4). (O'Kennedy et al., 2022)
• Immune Response: Mice vaccinated with a single dose of plant-produced chimaeric AHSV- 1/5 VLPs seroconverted at a 5 µg and 10 µg vaccine dose, within the first 14 days. The primary vaccination of AHSV-1/5 VLPs led to seroconversion of 1:40 (1.6 log10) and 1:28 (1.45 log10) when vaccinated with 5 and 10 lg AHSV-1/5 VLPs already on day 14, respectively. A booster vaccine was however necessary to elevate the neutralizing antibodies (nAbs) to 1:320 (2.5 log10) on day 28 for all VLP vaccine doses. Ten micrograms of soluble VP2 per mouse were required to equal this immune response after prime-boost vaccination. All the test antigens indicated a measure of CD4+/ CD8+ stimulation which is required to induce cell memory. Mice vaccinated with plant-produced AHSV-1/5 VLPs showed a larger increase in stimulation as compared to the OBP BEI inactivated vaccine as positive control and to a lesser extent for the soluble VP2 vaccinated mice. (O'Kennedy et al., 2022)
• Challenge Protocol: Groups 1–4 were challenged 28 days after the primary vaccine. Challenge with a dose containing 1.4 X 10^5 pfu of AHSV-5 per mouse on day 28 (14 days post booster immunization) was administered subcutaneously. (O'Kennedy et al., 2022)
• Efficacy: Protection against AHSV-5 conferred by both plant-produced adjuvanted VLPs and VP2 vaccines correlated strongly with SNTs determined during the immunogenicity study and mice (n = 6) of each group survived until day 25 post challenge when the study was terminated. The negative control group (PBS with adjuvant) succumbed within 8– 11 days after challenge. (O'Kennedy et al., 2022)