Search

This study describes the development and validation of a simplified enzyme-linked immunosorbent assay (ELISA) for the detection and discrimination of foot-and-mouth disease virus (FMDV) serotypes O, A, C and Asia 1. The multiplex ELISA was designed using selected, type-specific monoclonal antibodies (MAbs) coated onto ELISA plates as catching antibodies and a unique pan-FMDV MAb (1F10) as detector conjugate. Capture MAbs with the broadest intratypic reactivity were selected for each of the four FMDV serotypes by screening large panels of candidate MAbs with a wide spectrum of representative FMDV isolates. An additional pan-FMDV ELISA using 1F10 MAb for both capture and detection was used to complement the specific typing ELISAs to detect virus isolates, which might escape binding to the selected serotype-specific MAbs. This multiplex ELISA was prepared in a stabilized format, with immunoplates pre-coated with six MAbs and positive antigen controls already trapped by the relevant MAb, with the view to make available a diagnostic kit. Diagnostic performance of the MAbs-multiplex ELISA was analysed using 299 FMDV-positive epithelial suspensions representative of the antigenic and genomic variability within each serotype. Overall, the results provided evidence that the diagnostic performance of this assay platform is improved compared to the more complex polyclonal-based antigen detection ELISA; combining data from different serotypes and referring to the gold standard tests (i.e. virus isolation and/or RT-PCR), the MAbs-multiplex ELISA showed a sensitivity of 79% for the serotype-specific ELISA, compared to 72% for the polyclonal ELISA. The absence of reactivity of a minority of FMDV strains using the MAbs-multiplex ELISA can largely be attributed to deteriorated or low antigen concentration in the sample. This multiplex ELISA is simple, rapid and stable. FMDV antigenic diversity was adequately covered by the selected MAbs. Therefore, it can be used to replace existing polyclonal ELISAs for FMDV detection and serotyping., (© 2020 Blackwell Verlag GmbH.)

Two indirect, sandwich ELISAs are described for use in African swine fever (ASF) diagnosis. One assay uses polyclonal serum raised in rabbits and guinea pigs against the cytoplasmic soluble ASF virus protein and the second, a combination of monoclonal antibody raised against the VP73 protein and rabbit polyclonal serum. Both assays have been shown to detect antigen of representative field strains of phylogenetically distinct groupings of ASF virus but the ELISA, which utilises polyclonal antisera was slightly more sensitive than that using the monoclonal antibody.

Recombinant integrin alpha v beta6 was evaluated as a capture ligand in a sandwich ELISA for the detection and serotyping of foot-and-mouth disease (FMD) virus. Our routinely applied method employs seven serotype-specific rabbit polyclonal antibodies as capture ligands and seven serotype-specific guinea pig polyclonal antibodies as detecting reagents. The recombinant integrin bound FMD virus of all seven serotypes but not that of another vesicular disease, swine vesicular disease (SVD). Considerable heterotypic cross-reactions were evident when using the integrin capture ligand in combination with guinea pig detecting antibodies but totally type-specific reactions resulted when serotype-specific monoclonal antibodies (mabs) were used instead of the guinea pig reagents. The specificity of reaction of the integrin capture/mab detector combination was superior to that of our routinely employed rabbit/guinea pig ELISA and offers an improvement for test interpretation. As a universal trapping reagent for all FMD virus serotypes the alpha v beta6 recombinant protein also has the potential for application in other test procedures for viral identification (e.g. pen-side chromatographic strip-tests, biosensors, immunocapture RT-PCR, antigenic characterization procedures and monoclonal antibody profiling of emerging field virus strains) and in antibody detection assays employed for the diagnosis of FMD.

Abstract: Two lateral flow devices (LFD) for the detection of vesicular stomatitis (VS) virus (VSV), types Indiana (VSV-IND) and New Jersey (VSV-NJ) were developed using monoclonal antibodies C1 and F25VSVNJ-45 to the respective VSV serotypes. The performance of the LFDs was evaluated in the laboratory on suspensions of vesicular epithelia and cell culture passage derived supernatants of VSV. The collection of test samples included 105 positive for VSV-IND (92 vesicular epithelial suspensions and 13 cell culture antigens; encompassing 93 samples of subtype 1 [VSV-IND-1], 9 of subtype 2 [VSV-IND-2] and 3 of subtype 3 [VSV-IND-3]) and 189 positive for VSV-NJ (162 vesicular epithelial suspensions and 27 cell culture antigens) from suspected cases of vesicular disease in cattle and horses collected from 11 countries between 1937 and 2008 or else were derived from experimental infection and 777 samples that were either shown to be positive or negative for foot-and-mouth disease (FMD) virus (FMDV) and swine vesicular disease virus (SVDV) or else collected from healthy cattle or pigs and collected from 68 countries between 1965 and 2011. The diagnostic sensitivity of the VSV-IND (for reaction with VSV-IND-1) and VSV-NJ LFDs was either similar or identical at 94.6% (VSV-IND) and 97.4% (VSV-NJ) compared to 92.5% and 97.4% obtained by the reference method of antigen ELISA. The VSV-IND LFD failed to react with viruses of VSV-IND-2 and 3, while the VSV-NJ device recognized all VSV-NJ virus strains. The diagnostic specificities of the VSV-IND and VSV-NJ LFDs were 99.1% and 100, respectively, compared to 99.6% and 99.8% for the ELISA. Reactions with FMDV which can produce indistinguishable syndromes clinically in cattle, pigs and sheep and SVDV (vesicular disease in pigs) did not occur. These data illustrate the potential for the LFDs to be used next to the animal for providing rapid and objective support to veterinarians in their clinical judgment of vesicular disease and for the subtype (VSV-IND-1) and type-specific (VSV-NJ) pen-side diagnosis of VS and differential diagnosis from FMD. [Copyright &y& Elsevier]

Abstract: A sandwich ELISA using recombinant integrin αvβ6 as a capture ligand and serotype-specific monoclonal antibodies (Mabs) as detecting reagents has been compared with a polyclonal antibody based ELISA (using type-specific rabbit antibodies as capture and guinea pig antibodies as detectors), which is employed routinely at the FAO World Reference Laboratory for Foot-and-Mouth Disease (FMD), for the identification and serotyping of FMD virus (FMDV). The study used cell culture grown antigens (1351 FMDV positive) derived from suspected cases of vesicular disease collected from 86 countries between 1924 and 2011, those positive for the other vesicular diseases of swine vesicular disease (n =25) and vesicular stomatitis (n =45) and negative samples collected from uninfected cell cultures (n =36). The diagnostic sensitivity of the assays was similar at 98.1% (polyclonal ELISA) compared to 97.9% (integrin/Mab ELISA) but the serotypic-specificity of the latter was vastly superior (96%) to that of the former (61.5%). Reactions with the viruses of swine vesicular disease and vesicular stomatitis, which produce clinically indistinguishable syndromes in pigs and cattle, did not occur. The integrin/Mab ELISA recognized FMDV strains of wide antigenic and molecular diversity of all seven serotypes and although some FMDV isolates were not detected, the greater specificity of the assay, while retaining test sensitivity comparable to the conventional assay, warrants its consideration for adoption for routine diagnostic use. [Copyright &y& Elsevier]

Abstract: A lateral flow device (LFD) for the detection of all seven serotypes of foot-and-mouth disease virus (FMDV) was developed using a monoclonal antibody (Mab 1F10) shown to be pan-reactive to FMDV strains of each serotype by ELISA. The performance of the LFD was evaluated in the laboratory on suspensions of vesicular epithelia (304 positive and 1003 negative samples) from suspected cases of vesicular disease collected from 86 countries between 1965 and 2008 and negative samples collected from healthy animals. The diagnostic sensitivity of the LFD for FMDV was similar at 84% compared to 85% obtained by the reference method of antigen ELISA, and the diagnostic specificity of the LFD was approximately 99% compared to 99.9% for the ELISA. The device recognized FMDV strains of wide diversity of all seven serotypes but weaker reactions were often evident with those of type SAT 2, several viruses of which were not detected. Reactions with the viruses of swine vesicular disease and vesicular stomatitis that produce clinically indistinguishable syndromes in pigs and cattle, did not occur. The test procedure was simple and rapid, and typically provided a result within 1–10min of sample addition. Simple homogenizers that could be used in field conditions for preparing epithelial suspensions were demonstrated to be effective for LFD application. These data illustrate the potential for the LFD to be used next to the animal in the pen-side diagnosis of FMD and for providing rapid and objective support to veterinarians in their clinical judgment of the disease. [Copyright &y& Elsevier]

Abstract: A lateral flow device (LFD) for the detection of foot-and-mouth disease virus (FMDV) of the SAT 2 serotype was developed using a monoclonal antibody (Mab 2H6). The performance of the LFD was evaluated in the laboratory on suspensions of vesicular epithelia: 305 positive for FMDV type SAT 2 from suspected cases of vesicular disease collected from 30 countries and 1002 samples shown to be negative for FMDV type SAT 2 collected from 67 countries between 1968 and 2008. The diagnostic sensitivity of the LFD for FMDV type SAT 2 was higher at 88% compared to 79% obtained by the reference method of antigen ELISA, and the diagnostic specificity of the LFD was approximately 99% compared to 100% for the ELISA. The device recognized FMDV strains of wide diversity within the FMDV SAT 2 serotype and gave a superior performance for their detection compared to the 1F10 LFD which had been developed previously and shown to perform less well for the detection of FMDVs of this particular serotype. Reactions in the SAT 2 2H6 LFD with the viruses of other FMDV serotypes and swine vesicular disease (which produces a clinically indistinguishable syndrome in pigs), did not occur. These data illustrate the potential for the LFD to be employed to complement the 1F10 device next to the animal in the pen-side diagnosis of FMD, for providing rapid and objective support to veterinarians in their clinical judgment of the disease and for specific confirmation of a FMDV type SAT 2 infection. [Copyright &y& Elsevier]

Abstract: The solid-phase competition ELISA (SPCE) has been evaluated in both screening and titration assay formats for detecting antibodies against foot-and-mouth disease virus (FMDV) for the six non-O serotypes A, C, SAT 1, SAT 2, SAT 3 and Asia 1. Cut-off values were determined as a percentage inhibition of 40 for the SAT serotypes and 50 for serotypes A, C and Asia 1, which gave rise to specificity values ranging from 99.41% to 99.9% for the different serotypes. The relative sensitivity between the SPCE and LPBE/virus neutralisation test was 100%/109%. Antiserum titres derived by the SPCE for samples of serotypes O, A22 and Asia 1 were more than 11, 1 and 5 times of those determined by virus neutralisation test, respectively. This study indicated that the non-type O SPCEs have sufficient sensitivities and specificities for use as serological diagnostic tests for the qualitative and quantitative detection of antibodies against FMDV. [Copyright &y& Elsevier]

Abstract: A novel proximity ligation assay (PLA) using a pan-serotype reactive monoclonal antibody was developed and evaluated for the detection of foot-and-mouth disease virus (FMDV) in clinical samples collected from field cases of disease. The FMDV-specific PLA was found to be 100 times more sensitive for virus detection than the commonly used antigen capture-ELISA (AgELISA). As few as five TCID50 were detected in individual assays, which was comparable with the analytical sensitivity of real-time RT-PCR. Although this assay was capable of detecting diverse isolates from all seven FMDV serotypes, the diagnostic sensitivity of the PLA assay was lower than real-time RT-PCR mainly due to a failure to detect some SAT 1, SAT 2 and SAT 3 FMDV strains. In conclusion, this new PLA format has high analytical sensitivity for the detection of FMDV in clinical samples and may prove valuable as a rapid and simple tool for use in FMD diagnosis. [Copyright &y& Elsevier]