Development and application of ELISA test system for assessing humoral immunity against SAT2 topotype XIV foot-and-mouth disease virus

Introduction. Foot-and-mouth disease (FMD) is a highly contagious, economically significant disease of cloven-hoofed animals, characterized by vesicular symptoms. There are seven known foot-and-mouth disease virus (FMDV) serotypes (A, O, C, SAT 1, SAT 2, SAT 3 and Asia 1), which immunologically differ from each other. Special attention has been recently paid to FMDV of SAT2/XIV topotype (South African Territories 2) due to its rapid spread. One of the key methods of FMD control is vaccination and assessment of the susceptible animal immune status.

Objective. Development and testing of an enzyme-linked immunosorbent assay (ELISA) system based on the indirect liquid-phase blocking ELISA for the determination of antibodies to structural proteins of SAT2/XIV FMDV in order to evaluate the effectiveness of an FMD vaccine based on SAT-2/XIV/2023 FMDV antigen in the process of its production and subsequent use.

Materials and methods. The test material included experimental serum samples collected from cattle, pigs and white mice. The developed ELISA test system for assessing the level of post-vaccination antibodies against SAT2/XIV FMDV was validated through comparative testing with commercial test-kits: Test-kit for the determination of SAT 2 FMDV antibodies (Federal Centre for Animal Health, Russia) and “Solid-phase competitive ELISA for antibodies specific to FMDV serotype SAT 2”(IZSLER & The Pirbright Institute, Italy/Great Britain).

Results. The effectiveness of the proposed test system in detecting the induction of antibodies against SAT2/XIV FMDV was higher than that of other ELISA systems with the pronounced topotype specificity to the SAT2/VII FMD agent. Specific antibodies were detected in individual cattle on day 7 post vaccination. High diagnostic sensitivity (90%), specificity (98%) and accuracy (95%) ensured high degree of the ELISA results consistency with the known diagnostic status of the tested animals (k-criterion – 0.896).

Conclusion. Thus, the ELISA system for assessing humoral immunity against SAT2/XIV FMDV, which is 100% homologous with the vaccine strain and demonstrates high diagnostic parameters, is a reliable tool for assessing the quality of the SAT2/XIV FMD vaccine.

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