Development of a nano-gold immunodiagnostic assay for rapid on-site detection of invasive aspergillosis.

Development of a nano-gold immunodiagnostic assay for rapid on-site detection of invasive aspergillosis.

J Med Microbiol. 2019 Jul 29;:

Authors: Raval KM, Ghormade V, Rajamohanan PR, Choudhary H, Rudramurthy SM, Chakrabarti A, Paknikar K

Abstract
INTRODUCTION: Timely detection of invasive aspergillosis (IA) caused by fungal pathogens, i.e. Aspergillus fumigatus and Aspergillus flavus, in immunocompromised patients is crucial in preventing high mortality.
AIM: To develop a simple immunoassay for the detection of galactomannan (GM), an IA biomarker.
METHODOLOGY: GM from A. fumigatus and A. flavus clinical strains was purified and characterized by X-ray diffraction, IR spectroscopy and 13C/1H nuclear magnetic resonance (NMR) for polyclonal antibody (pAb) production in rabbits. An enzyme-linked immunosorbent assay (ELISA) was standardized using concanavalin A to capture Aspergillus GM and pAbs to detect it. Gold nanoparticles (AuNPs) were synthesized and conjugated to pAbs for the development of a dot-blot immunoassay. The developed dot-blot was evaluated with 109 clinical serum and bronchoalveolar lavage samples.
RESULTS: Spectroscopy studies characterized the d-galactofuranosyl groups of GM responsible for the immune response and generation of pAbs. The ELISA employing pAbs showed a sensitivity of 1 ng ml-1 for Aspergillus GM. Furthermore, a sensitive, visual, rapid dot-blot assay developed by the conjugation of pAbs to AuNPs (~24±5 nm size, -36±2 mV zeta potential) had a detection limit of 1 pg ml-1 in serum. The pAbs interacted with Aspergillus spp. but did not cross-react with other fungal pathogen genera such as Penicillium and Candida. Evaluation of the dot-blot with 109 clinical samples showed high sensitivity (80 %) and specificity (93.2 %), with an overall assay accuracy of 89%.
CONCLUSION: The developed nano-gold immunodiagnostic assay has immense potential for practical use in rapid, specific and sensitive on-site diagnosis of IA, even under resource-limited settings.

PMID: 31355743 [PubMed – as supplied by publisher]

Source: Industry