GB2196427A - Diagnostic kit - Google Patents

Abstract

A diagnostic kit, for example for diagnosing fish disease (such as furunculosis) by means of an enzyme-linked immunosorbent assay, comprises one or more probes 25, a container (not shown) and a support means 11. A portion of the probe is coated with a first reagent such as a monoclonal antibody. The support means comprises retaining means 37 and 39 for retaining the probe when not in use. First reaction wells 13 suitable for containing liquid second reagent (for example an enzyme-antibody conjugate) are provided. The reaction wells 13 are so shaped as to be able to retain the probe in contact with liquid reagent in the reaction well in use of the kit. <IMAGE>

Description

SPECIFICATION Diagnostic kit This invention relates to a diagnostic kit which is particularly suitable for use in non-laboratory situations, such as in the field. It is particularly envisaged that the kit will be of use to veterinary surgeons and to fish farmers in diagnosing diseases of fish.

Within the last ten years or so the advent of monoclonal antibody technology has enabled significant advances in diagnostic techniques to be made. Techniques have, in general, become cheaper, more specific and more reliable. From the chemical point of view, there is no reason why many diagnostic techniques could not be used outside the carefully controlled environment of the laboratory. However, up till now, there has not been made available hardware, for use in conjunction with the reagents for diagnosis, to enable accurate diagnosis to be made in the field.

According to the present invention there is provided a diagnostic kit comprising a probe and a support means, at least a portion of the probe being coated with a first reagent, and the support means comprising first retaining means for retaining the probe when not in use, a reaction well suitable for containing a liquid second reagent and second retaining means for retaining first reagent coated on the probe, in use of the kit, in contact with liquid second reagent in the reaction well.

The invention therefore enables a field worker to achieve results comparable with those obtained by sophisticated equipment in the laboratory but with minimal equipment and at low cost.

The kit may further comprise a first container for containing, when the kit is not in use, second reagent or a component of it, and the support means may comprise third retaining means for retaining the first container. The first container may contain an applicator such as a teat pipette for transferring liquid second reagent to the reaction well.

It is particularly preferred that the second retaining means of the support means be provided by the shape or configuration of the reaction well itself. This arrangement allows for particularly cost effective construction and may be realised by having the reaction well constitute a socket for the probe. The socket should in preference be a relatively close fit to the probe, but clearly there will be a limit to the degree of closeness that is appropriate, in view of the need for accommodation of an adequate volume of liquid second reagent accessible to the coated probe. To increase the amount of liquid reagent available, the reaction well may have one or more reservoir portions.

A construction which embodies all these principles and has been found to be particularly effective is when the probe, or at least a portion of it on which is coated the first reagent is in the form of a blade, and the reaction well is in the form of a slit having a widening, which may be centrally disposed.

The support means may be a tray, and the reaction well may be recessed into the tray. In a preferred embodiment, the reaction well constitutes a deep recess formed in a shallowly recessed portion of the tray: this allows for excess reagent forced out of the reaction well, on insertion of the probe, to be contained within the shallowly recessed portion, thereby avoiding spillage and enabling the coated portion of the probe to have access to further amounts of liquid reagent.

The support means may comprise first and second reaction wells, the or each first reaction well being suitable for containing a liquid second reagent and marked with a first indicia, and the or each second reaction well being suitable for containing a liquid third reagent and marked with a second indicia. When one or more second reaction wells are provided, a second container may also be provided for containing, when the kit is not in use, third reagent or a component of it; in such a case the support means can comprise fourth retaining means for retaining the second container.

The kit may comprise a plurality of probes and a corresponding plurality of reaction wells.

There may, for example, be five probes, five first reaction wells and five second reaction wells. The first container should be able to supply second reagent for all the first reaction wells and the second container should be able to supply third reagent for all the second reaction wells.

It has been found that a kit in accordance with the invention is particularly suitable for use in carrying out an enzyme-linked immunosorbent assay (ELISA). In such a case, the first reagent may be an antibody, the liquid second reagent may comprise enzyme-antibody conjugate and the liquid third reagent, when provided, may comprise substrate for the enzyme. Suitable enzymes for use in the ELISA include alkaline phosphatase and peroxidase. The antibody is preferably a monoclonal antibody.

In embodiments of the invention suitable for use by fish farmers, the antibody may be an antibody to an antigen characteristic of a condition (such as a disease) of fish, and the probe can in such cases be so constructed as to be suitable for insertion into fish tissue.

For a better understanding of the present invention, and to show how it may be put into effect, reference will now be made to the accompanying drawings, in which: FIGURE 1 shows a perspective view of a diagnostic kit in accordance with the present invention; FIGURES 2A and 2B show, respectively, front and side elevational views of a probe for use in the kit; FIGURE 3A shows a plan view of a tray being a support means for use in a kit of the present invention; FIGURES 3B and 3C show details of first retaining means for retaining the probe when not in use; FIGURE 4A shows a section view through a reaction well taken along the line IVA-IVA of Figure 4B; FIGURE 4B shows a top plan view of the reaction well shown in Figure 4A; and FIGURE 5 shows a top plan view of an alternative reaction well.

Referring now to the drawings, Figure 1 shows a diagnostic kit 1 in accordance with the invention comprising a case with a base 3 and a hinged lid 5, each having handle portions 7 and 9 which, when the container is closed, co-operate together to form a handle, by means of which the kit can be carried. On the inside of the lid 5 is mounted a sheet 27 bearing instructions for use of the kit.

In the base 3 is fitted a tray 11, which serves as a support means. Recessed into the tray 11 is a series of first reaction wells 13, a series of second reaction wells 15, a central recess 17 for accommodating probe retaining means, and three further recesses. The three further recesses are to retain containers containing reagents, or components of them.

They are designated as a first container recess 19, a second container recess 21 and a third container recess 23. Probes 25 can be seen retained by probe retaining means in the central recess and, for illustrative purposes, in one of the second reaction wells 15.

A probe 25 is illustrated more clearly in Figures 2A and 2B. It is generally flat and elongate and comprises a ribbed handle portion 27 and a coated blade portion 29 separated from the remainder of the probe by a collar 31. On one face of the probe is marked a serial number 33 for ease of reference by the user of the probe and a label 35 indicating the condition (in this case furunculosis) which the probe is to detect. The blade 29 is coated with monoclonal antibodies against the bacterial agent responsible for furunculosis, namely Aeromonas salmonicida.

Figure 3A shows the tray 11 which acts as a support means. In the central recess 17 are mounted first and second probe supports 37 and 39, which are shown in more detail, and in elevation, in Figures 3B and 3C respectively. Each of the probe supports 37 and 39 is provided with a series of castellations, between which the probes can be clipped into place and securely retained.

The first container recess 19 is for containing a liquid component of a second reagent.

The first reagent, it will be recalled, is a monoclonal antibody coated on the blade 29 of the probe 25. The second container recess 21 is for a container for a solid component of the second reagent. The solid component is antibody-enzyme conjugate for use in the enzyme linked immunosorbent assay. Liquid buffer in the container to go in the first container recess 19 can be used to dissolve enzyme-antibody conjugate in the container to go in the second container recess 21. The liquid container can be equipped with a teat pipette for this purpose, and the teat pipette can subsequently be used for transferring the solution into the first reaction wells 13.

The third container recess 23 is to retain a further container holding liquid substrate for the enzyme which is conjugated to the antibody. This container again has a teat pipette, by means of which the substrate can be transferred to the second reaction wells 15.

One of the first reaction wells is shown in more detail in Figures 4A and 4B. The interior of the reaction well is generally in the form of a slit corresponding in shape to the blade 29 of the probe 25. The reaction well therefore acts, as a socket for the probe. To enable a reasonable amount of liquid to be in contact with the probe, however, the slit is formed with a widening 41. In addition, it can be seen that the reaction well is deeply recessed from a shallow recess 43 formed in the tray 11. The reason for this is as follows. Liquid reagent is put into the reaction well 13 before the probe 25 is inserted. When the probe 25 is inserted, the level of liquid will rise. The shallow recess 43 prevents overspill and acts as a supplementary reservoir of liquid. The first reaction wells 13 are indicated by the shallow recess 43 being round.This is to be compared and contrasted with Figure 5, in which the second reaction well 15 can be seen to have a corresponding square-shaped shallow recess 45.

The kit is used as follows. Fish tissue coming from a fish suspected of having died of furunculosis is taken.

The blade 29 of the probe 25 is inserted into the tissue and left to incubate for ten minutes. The probe 25 is then extracted and washed well in clean cold water for one minute. The blade 29 was then put in one of the first reaction wells 13, which contained enzymeantibody conjugate dissolved in buffer. The immersion was continued for five minutes. At the end of the five minute immersion period, the probe 25 was extracted and the blade 29 was washed for one minute in clean cold water. The blade 29 was then inserted into a second reaction well 15, in which liquid substrate had been placed. The development of colour on the blade 29 indicated the presence of antigen characteristic of furunculosis.

Five probes 25, five first reaction wells 13 and five second reaction wells 15 are provided, so that five specimens of fish tissue can be analysed simultaneously.

Claims (17)

1. A diagnostic kit comprising a probe and a support means, at least a portion of the probe being coated with a first reagent, the support means comprising first retaining means for retaining the probe when not in use, a reaction well suitable for containing a liquid second reagent and second retaining means for retaining first reagent coated on the probe, in use of the kit, in contact with liquid second reagent in the reaction well.

2. A kit as claimed in Claim 1 further comprising a first container for containing, when the kit is not in use, second reagent or a component of it, and wherein the support means comprises third retaining means for retaining the first container.

3. A kit as claimed in Claim 1 or 2, wherein the second retaining means is provided by the shape or configuration of the reaction well.

4. A kit as claimed in Claim 3, wherein the reaction well constitutes a socket for the probe.

5. A kit as claimed in Claim 4, wherein the socket is close fitting to the probe.

6. A kit as claimed in Claim 4 or 5, wherein the reaction well has one or more reservoir portions.

7. A kit as claimed in Claim 4, 5 or 6, wherein at least a portion of the probe on which is coated the first reagent is in the form of a blade, and the reaction well is in the form of a slit having a widening.

8. A kit as claimed in any one of Claims 1 to 7, wherein the support means is a tray and the reaction well is recessed into the tray.

9. A kit as claimed in Claim 8, wherein the reaction well constitutes a deep recess formed in a shallowly recessed portion.

10. A kit as claimed in any one of Claims 1 to 9, wherein the support means comprises first and second reaction wells, the or each first reaction well being suitable for containing a liquid second reagent and marked with a first indicia, and the or each second reaction well being suitable for containing a liquid third reagent and marked with a second indicia.

11. A kit as claimed in Claim 10 further comprising a second container for containing, when the kit is not in use, third reagent or a component of it, and wherein the support means comprises fourth retaining means for retaining the second container.

12. A kit as claimed in any one of Claims 1 to 11 comprising a plurality of probes and a corresponding plurality of reaction wells.

13. A kit as claimed in any one of Claims 1 to 12 which is suitable for carrying out an enzyme linked immunosorbent assay and wherein the first reagent is an antibody, the liquid second reagent comprises enzyme-antibody conjugate and the liquid third reagent, when provided, comprises substrate for the enzyme.

14. A kit as claimed in Claim 13, wherein the antibody is monoclonal antibody.

15. A kit as claimed in Claim 13 or 14 wherein the antibody is an antibody to an antigen characteristic of a condition of fish and wherein the probe is suitable for insertion into fish tissue.

16. A kit as claimed in Claim 15, wherein the condition is a disease.

17. A kit substantially as herein described with reference to the accompanying drawings.