Validation and Field Assessment of a Rapid Lateral Flow Assay for Detection of Bovine Antibody toAnaplasma marginale

Abstract

The lateral flow assay (LFA) is a rapid diagnostic test which may be performed under most conditions and is especially useful for field applications. This type of assay was applied to the detection of antibody to bovine Anaplasma marginale using sera from endemic areas and from areas which have been free from infection for more than 25 years. Briefly, the test uses recombinant A. marginale major surface protein 5 peptide (Msp5), immobilized on a cellulose acetate membrane. A serum sample is added to a pad containing a monoclonal antibody specific for bovine IgG(1), conjugated with colloidal gold, located at one end of the strip. The sample and gold conjugate are wicked along the membrane and if antibody is present in the serum, a visible line will form between the Msp5-antibody-conjugate immune complex in minutes. An additional band of recombinant protein A/G was added to the membrane as a positive control reaction of the monoclonal antibody conjugate. For comparison, direct examination of blood smears and a nested polymerase chain reaction (PCR) were performed on some of the samples. Using samples from herds in one endemic area, the PCR gave a sensitivity value of 9.2% while a commercial competitive enzyme immunoassay (CELISA) gave a sensitivity value of 17.2% and the LFA values of 20.5%. In a second endemic area, selected samples, all positive by direct examination gave a 71.7% sensitivity values with the PCR, 94.5% with the CELISA and 95.5% with the LFA. Using sera from a disease-free area, the specificity values were 100% for the PCR (testing a proportion of randomly selected samples), 99.5% for the CELISA and 98.0% for the LFA. It is envisaged that the validated LFA will be a useful tool for screening cattle moving from an area with infection to a disease-free area.

A Review of Bovine Anaplasmosis

“…In a follow‐up study by the same authors, the LFA was validated and assessed under field conditions (Nielsen et al., 2009). Using 470 selected samples (all positive by direct microscopic examination) from non‐Canadian herds in an endemic area, the sensitivity of the semi‐nested PCR was determined to be 71.7%, while it was 94.5% for the cELISA and 95.5% for the LFA.…”

Lateral flow assays

“…A variety of biological samples can be tested using LFAs, including urine [ 5 ], saliva [ 6 ], sweat [ 7 , 8 ], serum [ 9 ], plasma [ 10 ], whole blood [ 10 , 11 ] and other fluids. Further industries in which LFA-based tests are employed include veterinary medicine [ 12 ], quality control [ 13 ], product safety in food production [ 14 ], and environmental health and safety [ 15 ]. In these areas of utilization, rapid tests are used to screen for animal diseases [ 16 ], pathogens [ 17 , 18 ], chemicals [ 19 ], toxins [ 20 ] and water pollutants [ 21 , 22 ], among others.…”

Biosensor Technologies in Medicine: from Detection of Biochemical Markers to Research into Molecular Targets (Review)

“…The diagnostic platforms-precursors of this innovative strategy include qualitative and semi-quantitative test systems for identifying specific antigens [9] and antibodies [10], as well as gene amplification products [11,12], based on latex agglutination, immunochromatography, and variations of lateral flow immunoassay (lateral flow assay, LFA; and lateral flow immunoassay, LFIA), which have not lost their significance for the diagnosis of infectious diseases these days [10,11,[13][14][15][16] (Figure 1).…”