A simple and rapid assay to evaluate purity of foot-and-mouth disease vaccine before animal experimentation

In-process quality control in foot-and-mouth disease vaccine production by detection of viral non-structural proteins using chemiluminescence dot blot assay

Foot-and-mouth disease (FMD) is a contagious viral disease of cloven-footed animals. Immunization with inactivated virus vaccine is effective to control the disease. Six-monthly vaccination regimen in endemic regions has proven to be effective. To enable the differentiation of infected animals from those vaccinated, non-structural proteins (NSPs) are excluded during vaccine production. While the antibodies to structural proteins (SPs) could be observed both in vaccinated and infected animals, NSP antibodies are detectable only in natural infection. Quality control assays that detect NSPs in vaccine antigen preparations, are thus vital in the FMD vaccine manufacturing process. In this study, we designed a chemiluminescence dot blot assay to detect the 3A and 3B NSPs of FMDV. It is sensitive enough to detect up to 20 ng of the NSP, and exhibited specificity as it does not react with the viral SPs. This cost-effective assay holds promise in quality control assessment in FMD vaccine manufacturing.

Development of a double-antibody sandwich ELISA for rapidly quantitative detection of residual non-structural proteins in inactivated foot-and-mouth disease virus vaccines

Foot-and-mouth disease (FMD) is a highly contagious and economically devastating disease of cloven-hoofed animals. Vaccination and surveillance against non-structure protein (NSP) are the most efficacious and cost-effective strategy to control this disease. Therefore, vaccine purity control is vital for successful prevention. Currently, vaccine purity is tested by an in-vivo test that recommended in the World Organization for Animal Health (WOAH), but it is time consuming and costly. Herein, we develop a double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) for quantitative detection of residual NSPs in inactivated FMD virus (FMDV) vaccines. In this assay, the monoclonal antibody 3A24 was selected as capture antibody and biotinylated 3B4B1 (Biotin-3B4B1) as detection antibody. A standard curve was developed using the NSP 3AB concentration versus OD value with the linear range of concentration of 2.5-160 ng/mL. The lowest limit of detection was 2.5 ng/mL. In addition, we determined 2.5 ng/mL of NSP as an acceptable threshold value of FMD vaccine purity using a dose-response experiment in cattle. The DAS-ELISA combined with the threshold value of FMD vaccine purity could provide a quick and simple tool for evaluation the antigenic purity of FMD vaccine during the manufacturing process.

Foot-and-Mouth Disease Virus Evades Innate Immune Response by 3C-Targeting of MDA5

Foot-and-mouth disease (FMD) is a highly contagious disease caused by FMD virus (FMDV) in cloven-hoofed animals. Retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated gene 5 (MDA5) are representative receptors in the cytoplasm for the detection of viral RNA and trigger antiviral responses, leading to the production of type I interferon. Although MDA5 is a crucial receptor for sensing picornavirus RNA, the interplay between MDA5 and FMDV is relatively unknown compared to the interplay between RIG-I and FMDV. Here, we observed that the FMDV infection inhibits MDA5 protein expression. Of the non-structural proteins, the Lb and 3C proteinases (Lbpro and 3Cpro) were identified to be primarily responsible for this inhibition. However, the inhibition by 3Cpro was independent of proteasome, lysosome and caspase-dependent pathway and was by 3C protease activity. A direct interaction between 3Cpro and MDA5 protein was observed. In conclusion, this is the first report that 3Cpro inhibits MDA5 protein expression as a mechanism to evade the innate immune response during FMDV infection. These results elucidate the pathogenesis of FMDV and provide fundamental insights for the development of a novel vaccine or therapeutic agent.

Determination of non-structural protein level for Turkey foot-and-mouth disease vaccine antigens during in-process

Purpose

The success of foot-and-mouth disease (FMD) serological serosurveillance greatly depends on the FMD vaccine which does not include any non-structural proteins (NSPs) of the FMD virus. Since pure FMD vaccines from NSPs are used with the FMD eradication programs using DIVA (Differentiating Infected from Vaccinated Animals) tests. Apart from the in-vivo test defined in the World Organisation for Animal Health, two different test kits were developed in-process NSP detection purposes. The first test kit was developed in 2010 and the second one has been very recently developed in 2019.

Materials and Methods

In this study, the level of NSP has been examined by first-chemiluminescent filtration assisted (FAL)-enzyme-linked immunosorbent assay (ELISA) based in-vitro, in-process test kit for Turkey FMD vaccine antigen samples. A total of 94 samples were used. The critical maximum acceptable levels of NSP were determined after purification stage of samples.

Results

As a maximum NSP level, 70 ng NSP for the polyethylene glycol concentrated samples and 30 ng NSP for the vaccine antigen mixture samples were accepted. A mini repeatability study was also performed. The correlation between the NSP, total protein, and 146S particul quantity of samples were analyzed.

Conclusion

As a conclusion, the chemiluminescent FAL-ELISA based test kit can be used for the NSP purity level determination of in-process samples.