U N I V E R S I T Y O F P R E T O R I AU N I V E R S I T E I T V A N P R E T O R I A

Y U N I B E S I T H I Y A P R E T O R I A

Faculty of Veterinary Science

RAPID DETECTION OF FOOT AND MOUTH DISEASE NON-STRUCTURAL PROTEINS USING A LATERAL FLOW ASSAY

1, 3 1 2 2 3Lazarus, D. D *., Wungak, Y. , Omotainse, O. S ., Talabi, A. O. , Fasina, F. O .

1 2Viral Research Division, National Veterinary Research Institute, Vom, Plateau State, Nigeria; Faculty of Veterinary Medicine, University of Agriculture, Abeokuta, Ogun State, Nigeria;3Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa.

IntroductionThe detection of antibodies to the non-structural (NS) proteins of the Foot and Mouth Disease Virus (FMDV) is of great importance for the detection of virus infected and carrier individual animals within a vaccinated herd and where the vaccination status of individual animals is not known. Since many animal species are hosts of this virus, a simple rapid test that allows a simultaneous screening for antibodies to FMDV in all the affected susceptible species is of great importance. We are presenting a preliminary report of a simple rapid lateral flow assay for the detection of antibodies to Non-Structural proteins of FMDV in the sera of infected cattle. This is a newly introduced product into the Nigerian livestock market, and we took time to preliminary evaluate its application in rapid diagnosis as a first line diagnostics for veterinarians especially where facilities for FMD diagnosis are not in place.

ObjectiveTo preliminarily access the performance of Foot and Mouth Disease NSP Ab Rapid Test kit.

Material and MethodsPrinciple of the assayQuicking Foot and Mouth Disease NSP Ab Rapid Test is based on sandwich lateral flow immuno-chromatographic assay. The test device has a testing window. The testing window has an invisible T (test) zone and C (control) zone. When sample is applied into the sample hole on the device, the liquid will laterally flow on the surface of the test strip. If there is enough FMD NSP antibodies in the sample, a visible T band will appear. The C band should always appear after a sample is applied, indicating a valid result. By this means, the device can accurately indicate the presence of FMD NSP antibodies in the sample. The panel of bovine sera that was used in this study was obtained from the serum bank of the Foot and Mouth Disease Research Centre, National Veterinary Research Institute, Vom-Nigeria.Test ProcedureThe lateral device cassettes were removed from the foil pouch and labelled according to the samples, panels of bovine sera thawed at room temperature were then dispensed gradually; 3 drops into the sample hole “S” of the cassette. This was allowed to flow along the surface of the test strip for 5-10 minutes. The results was observed and interpreted within 10 minutes test time. Result after 10 minutes is considered as invalid.

ResultsThe results obtained in this study showed a high level of sensitivity in comparison to conventional 3 ABC ELISA for FMD. In all the 40 panel of positive bovine sera tested by 3 ABC ELISA, 38 tested positive by this assay; a sensitivity of 95%. These results were obtained in full concordance with the results obtained from running the same panel of sera on 3 ABC ELISA for FMD.

DiscussionAn essential component of any disease control strategy includes the deployment of diagnostic assays to rapidly confirm the initial clinical determination of infection. The speed with which the results of suspected foot and mouth disease outbreak are released will maximise the efficiency of disease control to stop further spread to non-infected areas. This has become necessary considering the dynamics of transmission of FMD especially where large population of livestock exists within contiguous farms. The result obtained from this study demonstrates that the assay could be used for rapid sero-monitoring in outbreak situations. Furthermore, since it will differentiate infected from vaccinated animals, this will provide better epidemiological information for prompt actions. This assay although is not a substitute to the conventional ELISA protocol for the detection of antibodies against FMD NSP, can be used as a trigger for taking rapid measures at the site of suspected FMD outbreak before a confirmatory diagnosis is established in a national laboratory that has the facility for FMD diagnoses, thereby offering the possibility for implementing control measures more rapidly and limiting the spread of the outbreak. This assay is a simple direct test for the detection of antibodies to non-structural proteins of FMD in sera of infected animals, and can be carried out at penside. It is a rapid test which may be carried out on the field, next to the animal. It may be used for early detection of infection as first line diagnostics for veterinarians in slaughter houses, farms and in simply equipped national/regional laboratories to control the spread of infections. The test procedure is rapid and simple, providing a result within 10 minutes.

ConclusionThese results reaffirm the apparent high sensitivity of this assay to detect antibodies to NSPs following infection with FMD viruses.The results reported here originated from testing of field samples submitted during outbreaks and are in line with the laboratory-based comparisons between this assay and conventional 3 ABC ELISA which found this assay to have a high sensitivity for FMD NSP antibodies in sera of infected cattle.The results add further knowledge to the application of lateral flow assay for diagnosis of FMD NSP in sera of infected cattle in Nigeria.

ReferenceFoot and Mouth Disease NSP Antibodies Rapid Test Cat No. : W81058. Quicking Biotech Co., Ltd. No. 1998. South Yanggao Road, Shanghai China. Product Leaflet.

Fig. 1. Rapid Lateral Device cassette.

Fig. 2. Panel of bovine sera being dropped unto the cassette.

Fig. 3. The first cassette is a negative result and the second cassette is a positive result.

Fig. 4. 3 ABC ELISA plate

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