Upconverting phosphor technology-based lateral flow assay for the rapid and sensitive detection of anti-Trichinella spiralis IgG antibodies in pig serum

Abstract

Background Trichinella spiralis is a zoonotic food-borne parasite. A disease caused by infection with T. spiralis is called trichinellosis in humans. It is important to investigate the epidemic situation and the surveillance of herds and then prevent infection in humans. Therefore, this study is to develop a rapid and sensitive diagnostic method for on-site test in domestic and wild animals. Methods Upconverting phosphor nanoparticles (UCNPs), an excellent optical label, were conjugated with the excretory-secretory (ES) antigens from T. spiralis muscle larvae (ML) or goat anti-rabbit IgG, and a lateral flow (LF) assay based on these probes (UCNPs-ES/goat anti-rabbit IgG) was developed for the rapid and sensitive detection of anti-T. spiralis IgG antibodies in pig serum. The assay is named the UPT-LF-ES assay. In addition, the probes were characterized, and the assay was optimized. A cut-off threshold of the assay was also identified by using 169 known negative pig samples. Performance of the assay to T. spiralis with different infective numbers, cross-reactivity with other parasitic infections, the single-blinded experiment, and coincidence were evaluated with the assay. Results The UPT-LF-ES assay was successfully constructed and optimized based on the probes of UCNPs-ES/goat anti-rabbit IgG. In the pigs infected with 100, 1000, and 10,000 ML, positive results were first presented at 35 days post-infection (dpi), 30 dpi, and 25 dpi, respectively. The assay had no cross-reaction with other parasitic infections. A single-blinded experiment indicated that the sensitivity and specificity of the UPT-LF-ES assay were 100% and 100%, respectively, the area under the receiver operating characteristic (ROC) curve was 1.000. In addition, the value detected by the UPT-LF-ES assay was significantly different between positive and negative samples. Moreover, compared with the “gold standard” magnetic stirrer method, the coincidence rate of the UPT-LF-ES assay was 87.27%, and the kappa (K) coefficient was 0.7454, showing a substantial agreement. Conclusions The UPT-LF-ES assay is a useful point-of-care test (POCT) with T. spiralis in the detection of pig, which contributes to preventing human trichinellosis. Graphical Abstract

Scrub Typhus Diagnostics: The Present and the Future

“…Li et al have developed and evaluated a UCNP based assay for detection of anti-Trichinella spiralis IgG antibodies in pig serum. This assay is highly promising and has shown very good concordance with the gold standard [126]. Similar advancements in scrub typus detection may be highly useful for rapid diagnosis of scrub typhus.…”

Scrub typhus diagnostics: An overview

“…Assays to detect Yersinia pestis, Bacillus anthracis spore and Brucella spp (98) were evaluated in China and found to have a detection limit 10 5 CFU/ml, developed and evaluated an UCNP based assay for detection of anti-Trichinella spiralis IgG antibodies in pig serum. This assay is very promising as it showed very good concordance with gold standard (99). A similar advancement with scrub typus detection could be a game changer.…”

“…Recently, next generation sequencing (NGS) performed on clinical samples, metagenomic NGS (mNGS) has been used for identifying the etiology when conventional techniques have been unable to unravel the pathogen. NGS on various biological samples has been successfully performed to detect Orientia tsutsugamushi (98)(99)(100)(101)(102)(103). The summary of the cases for which NGS was used is described in the following paragraph.…”