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  • Sensitive and rapid lateral-flow assay for early detection of subclinical mammary infection in dairy cows.

Sensitive and rapid lateral-flow assay for early detection of subclinical mammary infection in dairy cows.

Scientific reports (2020-07-09)
Mohanned Naif Alhussien, Ajay Kumar Dang
ABSTRACT

Detection of subclinical mastitis (SCM) in its initial stage can save great economic losses, improve milk quality and animal welfare. We have developed a semiquantitative lateral flow assay for the detection of SCM in dairy cows targeting myeloperoxidase (MPO) enzyme of milk neutrophils. A competitive immunoassay format was used, and colloidal gold nanoparticles (GNP) were prepared and used as a labelling agent. Monoclonal anti-MPO antibodies were used and assessed for its quality by enzyme-linked immunosorbent assay and dot blot. Conjugation method for GNP and anti-MPO antibodies was standardised, and the conjugate was placed over the conjugate pad. MPO coupled with a carrier protein (OVA) and the species-specific secondary antibodies were placed on test and control lines, respectively. The developed assay was verified with 75 milk samples collected from healthy, SCM and clinical mastitis cows. It displayed a high sensitivity as it could detect MPO as low as 1.5 ng/ml, an accuracy greater than 97% and showed no crossreactivity when crosschecked with other milk proteins. The developed assay can be used as an alternative for SCM diagnostic tests where lab structure are available for obtaining the lysate of milk SCC.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Histopaque®-1119, sterile-filtered, density: 1.119 g/mL
Sigma-Aldrich
Methylene blue, certified by the Biological Stain Commission
Sigma-Aldrich
Lactoferrin from bovine milk, ≥85% (SDS-PAGE)
Sigma-Aldrich
Xylenes, reagent grade
Sigma-Aldrich
Bovine Serum Albumin, lyophilized powder, ≥96% (agarose gel electrophoresis)
Sigma-Aldrich
Lactoperoxidase from bovine milk, lyophilized, powder, ≥150 U/mg
Sigma-Aldrich
Anti-Mouse IgG (Fc specific)–Peroxidase antibody produced in goat, affinity isolated antibody
Sigma-Aldrich
Histopaque®-1077, sterile-filtered, density: 1.077 g/mL