• Vaccine Name: Foot-and-mouth disease virus vaccine rFMDVΔ3A^87-144
• Target Pathogen: Foot-and-mouth disease virus
• Target Disease: Foot-and-mouth disease
• Type: Recombinant vector vaccine
• Status: Research
• Host Species for Licensed Use: None
• Antigen: cDNA clone for FMDV serotype A Indian vaccine strain lacking 58 amino acid residues (87-144 amino acid position) in the carboxy-terminal region of the viral 3A protein. (Dhanesh et al., 2020)
• Preparation: The rFMDVΔ3A^87-144 viruses were grown in BHK-21 monolayer in roller bottles and harvested after observing complete CPE. The virus supernatant was inactivated with 3 mM BEI for 24 h at room temperature after chloroform clarification. Three back passaging of the inactivated virus in BHK-21 were carried out to ensure the absence of residual infectivity. The inactivated virus was concentrated with PEG as described earlier and purified by cesium chloride density gradient ultracentrifugation to estimate the antigen content in the concentrated suspension by spectrophotometer. The vaccines were formulated by blending the PEG concentrated antigen and MontanideISA-201 VG adjuvant (Seppic, France) by homogenization to have 1.2 μg antigen per dose in 250 μl vaccine. (Dhanesh et al., 2020)
• Immunization Route: Intradermal injection (i.d.)
• Description: rFMDVΔ3A^87-144 vaccine induces potent immune response with 100% protective efficacy upon challenge with homologous virus in guinea pigs. (Dhanesh et al., 2020)

Guinea pig Response

• Vaccination Protocol: Thirty-six healthy male guinea pigs of 3 months age were randomly divided into three groups of 12 each. The first group received 1.2 μg of FMDV^WT virus antigen, and the second group received a similar dose of rFMDVΔ3A^87-144 virus antigen. The third group received phosphate-buffered saline to serve as the control. All the three groups received a similar dose of booster injections of respective antigen post 28 days of primary immunization. (Dhanesh et al., 2020)
• Immune Response: The FMDV^WT and rFMDVΔ3A^87-144 vaccinated group developed a mean serum titer of 1.38 log10SN50 and 1.35 log10SN50, respectively, on 28 dpv. Further, the serum titer of both the groups increased to 1.87 log10SN50 and 1.70 log10SN50, respectively, by 28 dpb, indicating a potent anamnestic immune response on second exposure with the antigen. Both conventional and the deletion mutant virus vaccine produced a similar immune response with no significant difference (p > 0.05). (Dhanesh et al., 2020)
• Challenge Protocol: After 28 days post-booster, all the groups were challenged with 100 GPID50 of guinea pig adapted FMDV^WT in 50-μl volume by intradermal tracking in the left rear footpad. (Dhanesh et al., 2020)
• Efficacy: 100% protection was conferred by both vaccines as no systemic infection was noticed in any of the vaccinated animals. (Dhanesh et al., 2020)