A Novel Immunochromatographic Test Strip Using Lanthanide-Labeled Fluorescent Nanoparticles for the Serological Detection ofin Dogs and Cats.

Abstract

() is an important zoonotic pathogen which induces both acute and chronic toxoplasmosis. Timely diagnosis ofis crucial for effective disease management. Here, we present a pioneering approach using europium (III)-chelated nanoparticles (EuNPs) in a rapid lateral flow immunochromatographic test strip (ICTS) for detectingantibodies in serum samples. By conjugating EuNPs with Staphylococcus aureus protein A, we efficiently captured-specific antibodies, which bound toantigens on the test line (T-line), generating a distinct fluorescent signal. Employing this novel method, we conducted an extensive epidemiological investigation ofinfections among dogs and cats in Shanghai, China. This innovative ICTS allows for rapid results within 25 min, which include a qualitative result through naked-eye observation under an ultraviolet lamp and a quantitative one derived using a strip reader. With a detection limit of 1:6400 for dog positive serum and no cross-reactivity with other canine and feline pathogens, the EuNPs-ICTS demonstrated excellent consistency with standard enzyme-linked immunosorbent assay results for dogs (κ = 0.91) and cats (κ = 0.92). In addition, 20.38% of 996 dog serum samples and 14.18% of 416 cat serum samples revealedantibodies, highlighting the efficacy of this approach. Our study presents a rapid, sensitive, specific, and reproducible EuNPs-ICTS, serving as a promising tool for on-the-spot diagnosis ofinfections in dogs and cats.