Diagnostics for the Real World, Ltd.

Helen Lee

Magda Anastassova Dineva

Hsiang Yun Hu

Ling Huang

Shaun Christopher Hazlewood

Dipstick tests for detecting analyte are described. In a preferred embodiment, a multiple biotinylated antibody capable of binding analyte is bound to an anti-biotin antibody labelled with colloidal gold and wicked up the dipstick with test solution thought to contain analyte. Complex formed between analyte, biotinylated anti-analyte antibody, and colloidal gold labelled anti-biotin antibody is captured at a capture zone of the dipstick. Presence of colloidal gold label at the capture zone indicates the presence of analyte in the test solution. The sensitivity of analyte detection using such methods is an order of magnitude higher than for comparable methods in which biotinylated anti-analyte antibody bound to analyte is wicked up the dipstick in a first step, and a colloidal gold labelled anti-biotin antibody is wicked up the dipstick in a separate step. Kits for performing the tests of the invention are also described.

Signal enhancement system with multiple labeled-moieties

Use of dipsticks to test for the presence of target nucleic acid in a sample solution is described. The dipsticks comprise a contact end for contacting the sample solution and a capture zone, remote from the contact end, to which a capture probe is immobilized. The capture probe is capable of hybridising to the target nucleic acid. The sample solution is contacted with the contact end of the dipstick and travels by capillary action to the capture zone. If target nucleic acid is present in the sample solution it is captured and can be detected at the capture zone. The capture probe is immobilized to the capture zone by a spacer. Use of the spacer increases the stability of the interaction between the capture probe and the target nucleic acid and thus improves the sensitivity of target nucleic acid detection. Detection probes with spacers are also described.

Binding interactions in dipstick assays

Dipstick tests for detecting analyte are described. In a preferred embodiment, a multiple biotinylated antibody capable of binding analyte is bound to an anti-biotin antibody labeled with colloidal gold and wicked up the dipstick with test solution thought to contain analyte. Complex formed between analyte, biotinylated anti-analyte antibody, and colloidal gold labeled anti-biotin antibody is captured at a capture zone of the dipstick. Presence of colloidal gold label at the capture zone indicates the presence of analyte in the test solution. The sensitivity of analyte detection using such methods is an order of magnitude higher than for comparable methods in which biotinylated anti-analyte antibody bound to analyte is wicked up the dipstick in a first step, and a colloidal gold labeled anti-biotin antibody is wicked up the dipstick in a separate step. Kits for performing the tests of the invention are also described.

Use of helper probes in dipstick assays is described. In a dipstick assay to test for the presence of a target nucleic acid in a sample solution, the sample solution is contacted with the contact end of the dipstick to cause the sample solution to move by capillary action to a capture zone of the dipstick at which target nucleic acid is captured. The target nucleic acid may be captured at the capture zone by a capture probe capable of hybridising to the target nucleic acid. A labelled detection probe capable of hybridising to the target nucleic acid may be used to detect the target nucleic acid at the capture zone. A helper probe may be used to enhance the binding of the capture and/or detection probe to the target nucleic acid, thereby improving the sensitivity of target nucleic acid detection. Dipsticks and kits are also described.

Capture and detection of target nucleic acid in dipstick assays

The invention provides a dipstick and a kit comprising the dipstick, for testing for the presence of a plurality of different targets in a sample solution which comprises: a dipstick having a plurality of different capture zones and, immobilised to each capture zone, a different capture moiety, each capture moiety capable of capturing a different target; and, separately, a plurality of different detection probes, each detection probe capable of binding to a different target and each detection probe being labelled with or enabling the formation of a detection signal so that the presence of each target is indicated by the formation of a signal at the capture zone for that target; wherein the target for at least two of the capture moieties is a disease causing micro-organism or a marker indicating the existence of a disease, disorder, or condition of the host from which the sample solution was derived, and wherein at least two of the capture moieties are capable of binding to different components or markers of the same disease causing micro-organism as targets for those capture moieties. The dipsticks and kits may be used for confirmatory assays of infection by an infectious agent or disease causing microorganisms.

Dipstick assay

Dipsticks for testing for the presence of a target nucleic acid in a sample solution are described the dipsticks comprise a universal capture probe immobilised at a capture zone of the dipstick. The universal capture probe is capable of hybridising to a hook capture probe which is hybridised to the target nucleic acid in the sample solution. A contact end of the dipstick is contacted with the sample solution to cause hook capture probe hybridised to the target nucleic acid to move by capillary action to the capture zone where the target nucleic acid can be detected. Use of the universal and hook capture probes allows dipsticks to be prepared which can be used to capture any target nucleic acid, thereby simplifying preparation of the dipsticks. Specificity of target nucleic acid capture is then achieved by use of an appropriate hook capture probe. Methods and kits are also described.

Capture and detection format versatility for dipstick assays

Use of helper probes in dipstick assays is described. In a dipstick assay to test for the presence of a target nucleic acid in a sample solution, the sample solution is connected with the contact end of the dipstick to cause the sample solution is contacted with the contact end of the dipstick to cause the sample solution to move by capillary action to a capture zone of the dipstick at which target nucleic acid is captured. The target nucleic acid may be captured at the capture zone by a capture probe capable of hybridising to the target nucleic acid. A labelled detection probe capable of hybridising to the target nucleic acid may be used to detect the target nucleic acid at the capture zone. A helper probe may be used to enhance the binding of the capture and/or detection probe to the target nucleic acid, thereby improving the sensitivity of target nucleic acid detection. Dipsticks and kits are also described.

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Cambridge, United Kingdom

Helen Lee