Gold nanoparticle dimer-based immunochromatography for in situ ultrasensitive detection of porcine epidemic diarrhea virus.

The low detection sensitivity of lateral-flow immunochromatography assay (LFIA) based on spherical gold nanoparticle (AuNP) limits its wide applications. In the present study, AuNP dimers with strong plasma scattering and robust signal output were synthesized via the Ag ion soldering (AIS) strategy and used as labeled probes in LFIA to boost the sensitivity without any extra operation process and equipment. The established LFIA exhibited high sensitivity with a limit of detection (LOD) of 2.0 × 102 TCID50/mL for PEDV, which provides 50 times higher sensitivity than commercial LFIA based on spherical colloidal gold. In addition, the AuNP dimer-based LFIA showed strong specificity, good reproducibility, high stability, and good accordance to reverse transcription polymer chain reaction (RT-PCR) when detecting 109 clinical samples. Thus, the AuNP dimers is a promising probe for LFIA and the developed AuNP dimer-based LFIA is suitable for the rapid detection of PEDV in the field.

Evaluation of a Lateral Flow Immunochromatography Assay (LFIA) for Diagnosis and Surveillance of Brucellosis in French Alpine Ibex (Capra ibex).

France has been officially free of bovine brucellosis since 2005. Nevertheless, in 2012, as the source of two human cases, a bovine outbreak due to B. melitensis biovar 3 was confirmed in the French Alpine Bargy massif, due to a spillover from wild, protected Alpine ibex (Capra ibex). In order to reduce high Brucella prevalence in the local ibex population, successive management strategies have been implemented. Lateral flow immunochromatography assay (LFIA) was thus identified as a promising on-site screening test, allowing for a rapid diagnosis far from the laboratory. This study compared a commercial LFIA for brucellosis diagnosis with the WOAH-recommended tests for small ruminants (i.e., Rose Bengal test (RBT), Complement fixation test, (CFT) and Indirect ELISA, (iELISA)). LFIA showed the same analytical sensitivity as iELISA on successive dilutions of the International Standard anti-Brucella melitensis Serum (ISaBmS) and the EU Goat Brucella Standard Serum (EUGBSS). Selectivity was estimated at 100% when vaccinated ibex sera were analyzed. When used on samples from naturally infected ibex, LFIA showed high concordance, as well as relative sensitivity and specificity (>97.25%) in comparison with RBT and CFT. This work shows high reliability and ensures a better standardization of LFIA testing for wild ruminants.

Point-of-Care Tests for Rapid Detection of Porcine Epidemic Diarrhea Virus: A Systematic Review and Meta-Analysis.

The timely and accurate diagnosis of porcine epidemic diarrhea virus (PEDV) infection is crucial to reduce the risk of viral transmission. Therefore, the objective of this review was to evaluate the overall diagnostic accuracy of rapid point-of-care tests (POCTs) for PEDV. Studies published before 7 January 2022 were identified by searching PubMed, EMBASE, Springer Link, and Web of Science databases, using subject headings or keywords related to point of care and rapid test diagnostic for PEDV and PED. Two investigators independently extracted data, rated risk of bias, and assessed the quality using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. The bivariate model and the hierarchical summary receiver operating characteristic (HSROC) model were used for performing the meta-analysis. Threshold effect, subgroup analysis, and meta-regression were applied to explore heterogeneity. Of the 2908 records identified, 24 eligible studies involving 3264 specimens were enrolled in the meta-analysis, including 11 studies on evaluation of lateral flow immunochromatography assay (ICA)-based, and 13 on nucleic acid isothermal amplification (NAIA)-based POCTs. The overall pooled sensitivity, specificity and diagnostic odds ratio (DOR) were 0.95 (95% CI: 0.92-0.97), 0.96 (95% CI 0.88-0.99) and 480 (95% CI 111-2074), respectively; for ICA-based POCTs and the corresponding values for NAIA-based, POCTs were 0.97 (95% CI 0.94-0.99), 0.98 (95% CI 0.91-0.99) and 1517 (95% CI 290-7943), respectively. The two tests showed highly comparable and satisfactory diagnostic performance in clinical utility. These results support current recommendations for the use of rapid POC tests when PEDV is suspected.

Development of a rapid lateral flow immunochromatography assay for the detection of group-specific antibodies against VP7 protein of bluetongue virus in multiple species.

Bluetongue virus (BTV), the causative agent of bluetongue disease infects many domestic and wild ruminants. In the present study, colloidal gold nanoparticle-based lateral flow immunochromatography assay (LFIA) was developed to detect the group-specific antibodies to BTV in serum samples of sheep, goats, cattle, and camel. The recombinant VP7 protein of BTV conjugated to colloidal gold nanoparticles (GNPs) was used as a detector reagent. Recombinant streptococcal protein G and monoclonal antibody to BTV group-specific antigen were immobilized as the test and the control line, respectively on a nitrocellulose membrane. The protein G could capture the specific antibodies to BTV present in the serum of multiple ruminant species susceptible to BTV in a common test format and could eliminate the requirement of multiple anti-species antibodies. Upon addition of serum sample, GNP-rVP7 protein-serum complex migrated laterally onto the strip via capillary action and results were analyzed based on appearance of red colour band at test and control line. Serum samples (n = 481) of sheep, goats, cattle, and camel segregated as positive and negative by the commercial competitive-ELISA (c-ELISA) kit were tested in the fabricated LFIA strips to analyze the performance of the assay. In comparison with c-ELISA, the relative diagnostic sensitivity (DSn) of 95.2% with 91.6-97.6 (95%)) confidence interval and relative diagnostic specificity (DSp) of 99.6% 97.8-100.0 (95%) confidence interval were obtained for the optimized LFIA. The agreement between the LFIA and the c-ELISA was excellent as indicated by the kappa coefficient value of 0.949 (SE = 0.0142) with 0.9219 to 0.9779 (95%) confidence interval. The recombinant protein G based LFIA is a sensitive, specific, rapid, one-step test that can be used in the field or poorly equipped laboratories for serological diagnosis and serosurveillance of bluetongue in multiple susceptible species.