Comparison of Test Methodologies for Foot-and-Mouth Disease Virus Serotype A Vaccine Matching

Abstract

Vaccination has been one of the most important interventions in disease prevention and control. The impact of vaccination largely depends on the quality and suitability of the chosen vaccine. To determine the suitability of a vaccine strain, antigenic matching is usually studied by in vitro analysis. In this study, we performed three in vitro test methods to determine which one gives the lowest variability and the highest discriminatory capacity. Binary ethylenimine inactivated vaccines, prepared from 10 different foot-and-mouth disease (FMD) virus serotype A strains, were used to vaccinate cattle (5 animals for each strain). The antibody titers in blood serum samples 3 weeks postvaccination (w.p.v.) were determined by a virus neutralization test, neutralization index test, and liquid-phase blocking enzyme-linked immunosorbent assay (ELISA). The titers were then used to calculate relationship coefficient (r 1 ) values. These r 1 values were compared to the genetic lineage using receiver operating characteristic (ROC) analysis. In the two neutralization test methods, the median titers observed against the test strains differed considerably, and the sera of the vaccinated animals did not always show the highest titers against their respective homologous virus strains. When the titers were corrected for test strain effect (scaling), the variability (standard error of the mean per vaccinated group) increased because the results were on a different scale, but the discriminatory capacity improved. An ROC analysis of the r 1 value calculated on both observed and scaled titers showed that only r 1 values of the liquid-phase blocking ELISA gave a consistent statistically significant result. Under the conditions of the present study, the liquid-phase blocking ELISA showed less variation and still had a higher discriminatory capacity than the other tests.

Cross-Protection Induced by a A/MAY/97 Emergency Vaccine Against Intra-Serotype Heterologous Challenge with a Foot-and-Mouth Disease Virus from the A/ASIA/G-VII Lineage

“…Therefore, managers of vaccine banks should not require vaccine of >6 PD 50 /dose but should know the homologous potency to be able to predict the protection against circulating field viruses, using in-vitro vaccine matching results (e.g., r 1 -value) as predictor of the cross-protection-ratio. Although in this study and a previous study [22] the cross-protection-ratio matches reasonably well with the r 1 -value, more research is needed to validate this for more strains, especially as the variation in both r 1 -value determination and potency tests is considerable [23][24][25][26].…”

Cross-protection induced by a A/MAY/97 Emergency Vaccine Against Heterologous Challenge with a Foot-and-mouth Disease Virus from the A/ASIA/G-VII Lineage

“…r1-value) as predictor of the cross-protection-ratio. Although in this study and a previous study [22] the cross-protection-ratio matches reasonably well with the r1-value, more research is needed to validate this for more strains, especially as the variation in both r1-value determination and potency tests is considerable [23][24][25][26].…”

Foot-and-Mouth Disease Seroprevalence in Cattle in Eritrea

“…The validation of the VNT was performed with Dutch sera because no well‐defined sera were available from African cattle. Previous FMD vaccination studies showed responses in Eritrean cattle which were similar to responses observed in European cattle (Tekleghiorghis et al., ,b). Therefore, we consider the use of Dutch cattle for validation of the VNTs used on cattle sera collected in Eritrea valid.…”