Evaluation of Equine Infectious Anemia Virus by the Indirect Enzyme-linked Immunosorbent Assay EIA-LAB as Screening Tools in Mexico

Equine infectious anemia is a worldwide distributed disease that affects the Equide family. Commercial effective vaccine is not available, for that reason control of the disease depends on diagnostic tools. To improve the efficiency of the diagnostic program in Cuba, LABIOFAM Group, developed an indirect enzyme-linked immunosorbent assay (ELISA), ELISA kit, to complement the diagnostic system that currently uses the agar gel immunodiffusion (AGID) kit. The ELISA AIE-LAB Kit was evaluated in a Mexican context, compared with the gold standard test Agar gel immunodiffusion, AGID AIE-LABIOFAM, and commercial AGID kit. The analytical sensitivity was determined using serial dilutions twofold of the positive control serum to establish the range of detected antibodies in relation to the cutoff value of the plate (OD 0.300). A precision study was carried out to evaluate repeatability, intermediate precision, and reproducibility by estimating the standard deviation and coefficient of variation. The precision results were satisfactory and the values of the coefficient of variation were considered adequate to guarantee an excellent consistency of the ELISA AIE-LAB. The diagnostic performance of the ELISA AIE-LAB involved the evaluation of specificity, sensitivity, and concordance in comparison with both AGID tests. The diagnostic sensitivity was 100% and the specificity 97.6%, with a very good degree of concordance (Kappa = 0.9). The results suggest that the ELISA AIE-LAB test could be used in Mexico as a diagnostic system for the detection of specific antibodies against the equine infectious anemia virus, as per current international norms.

Deep sequencing of phage-displayed peptide libraries reveals sequence motif that detects norovirus

Norovirus infections are the leading cause of non-bacterial gastroenteritis and result in about 21 million new cases and $2 billion in costs per year in the United States. Existing diagnostics have limited feasibility for point-of-care applications, so there is a clear need for more reliable, rapid, and simple-to-use diagnostic tools in order to contain outbreaks and prevent inappropriate treatments. In this study, a combination of phage display technology, deep sequencing and computational analysis was used to identify 12-mer peptides with specific binding to norovirus genotype GI.1 virus-like particles (VLPs). After biopanning, phage populations were sequenced and analyzed to identify a consensus peptide motif-YRSWXP. Two 12-mer peptides containing this sequence, NV-O-R5-3 and NV-O-R5-6, were further characterized to evaluate the motif's functional ability to detect VLPs and virus. Results indicated that these peptides effectively detect GI.1 VLPs in solid-phase peptide arrays, ELISAs and dot blots. Further, their specificity for the S-domain of the major capsid protein enables them to detect a wide range of GI and GII norovirus genotypes. Both peptides were able to detect virus in norovirus-positive clinical stool samples. Overall, the work reported here demonstrates the application of phage display coupled with next generation sequencing and computational analysis to uncover peptides with specific binding ability to a target protein for diagnostic applications. Further, the reagents characterized here can be integrated into existing diagnostic formats to detect clinically relevant genotypes of norovirus in stool.

A conformational epitope mapped in the bovine herpesvirus type 1 envelope glycoprotein B by phage display and the HSV-1 3D structure

The selected dodecapeptide (1)DRALYGPTVIDH(12) from a phage-displayed peptide library and the crystal structure of the envelope glycoprotein B (Env gB) from Herpes Simplex Virus type 1 (HSV-1) led us to the identification of a new discontinuous epitope on the Bovine herpesvirus type 1 (BoHV-1) Env gB. In silico analysis revealed a short BoHV-1 gB motif ((338)YKRD(341)) within a epitope region, with a high similarity to the motifs shared by the dodecapeptide N-terminal region ((5)YxARD(1)) and HSV-1 Env gB ((326)YARD(329)), in which the (328)Arg residue is described to be a neutralizing antibody target. Besides the characterization of an antibody-binding site of the BoHV-1 Env gB, we have demonstrated that the phage-fused peptide has the potential to be used as a reagent for virus diagnosis by phage-ELISA assay, which discriminated BoHV-1 infected serum samples from negative ones.

Development, evaluation, and laboratory validation of immunoassays for the diagnosis of equine infectious anemia (EIA) using recombinant protein produced from a synthetic p26 gene of EIA virus

Equine infectious anemia (EIA)-a retroviral disease caused by equine infectious anemia virus (EIAV)-is a chronic, debilitating disease of horses, mules, and donkeys. EIAV infection has been reported worldwide and is recognized as pathogen of significant economic importance to the horse industry. This disease falls under regulatory control program in many countries including India. Control of EIA is based on identification of inapparent carriers by detection of antibodies to EIAV in serologic tests and "Stamping Out" policy. The current internationally accepted test for diagnosis of EIA is the agar gel immune-diffusion test (AGID), which detects antibodies to the major gag gene (p26) product. The objective of this study was to develop recombinant p26 based in-house immunoassays [enzyme linked immunosorbent assays (ELISA), and AGID] for EIA diagnosis. The synthetic p26 gene of EIAV was expressed in Escherichia coli and diagnostic potential of recombinant p26 protein were evaluated in ELISA and AGID on 7,150 and 1,200 equine serum samples, respectively, and compared with commercial standard AGID kit. The relative sensitivity and specificity of the newly developed ELISA were 100 and 98.6 %, respectively. Whereas, relative sensitivity and specificity of the newly developed AGID were in complete agreement in respect to commercial AGID kit. Here, we have reported the validation of an ELISA and AGID on large number of equine serum samples using recombinant p26 protein produced from synthetic gene which does not require handling of pathogenic EIAV. Since the indigenously developed reagents would be economical than commercial diagnostic kit, the rp26 based-immunoassays could be adopted for the sero-diagnosis and control of EIA in India.