Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L3/00—Containers or dishes for laboratory use, e.g. laboratory glassware; Droppers
  • B01L3/02—Burettes; Pipettes
  • B01L3/021—Pipettes, i.e. with only one conduit for withdrawing and redistributing liquids
  • B01L3/0217—Pipettes, i.e. with only one conduit for withdrawing and redistributing liquids of the plunger pump type
  • B01L3/022—Capillary pipettes, i.e. having very small bore
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
  • C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
  • C12Q1/58—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving urea or urease
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
  • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
  • G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
  • G01N33/531—Production of immunochemical test materials
  • G01N33/532—Production of labelled immunochemicals
  • G01N33/535—Production of labelled immunochemicals with enzyme label or co-enzymes, co-factors, enzyme inhibitors or enzyme substrates
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
  • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
  • G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
  • G01N33/543—Immunoassay; Biospecific binding assay; Materials therefor with an insoluble carrier for immobilising immunochemicals
  • G01N33/54366—Apparatus specially adapted for solid-phase testing
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N35/00—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor
  • G01N2035/00178—Special arrangements of analysers
  • G01N2035/00237—Handling microquantities of analyte, e.g. microvalves, capillary networks
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N35/00—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor
  • G01N35/10—Devices for transferring samples or any liquids to, in, or from, the analysis apparatus, e.g. suction devices, injection devices
  • G01N2035/1027—General features of the devices
  • G01N2035/1048—General features of the devices using the transfer device for another function
  • G01N2035/1055—General features of the devices using the transfer device for another function for immobilising reagents, e.g. dried reagents
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N35/00—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor
  • G01N35/10—Devices for transferring samples or any liquids to, in, or from, the analysis apparatus, e.g. suction devices, injection devices
  • G01N2035/1027—General features of the devices
  • G01N2035/1048—General features of the devices using the transfer device for another function
  • G01N2035/1062—General features of the devices using the transfer device for another function for testing the liquid while it is in the transfer device

Definitions

• This invention relates to improvements in methods, test kits and apparatus for performing enzyme- linked immunosorbent assays for the detection and quantitative determination of antigens and antibodies.
• the present invention relates to improvements in methods, test kits and apparatus which enable such assays to be performed by following a simple procedure which does not require the use of elaborate laboratory equipment or trained laboratory personnel, and hence may be performed under relatively adverse conditions, for example in the field.
• the prior specification describes apparatus for detecting or determining the presence of antigenic or haptenic substances or antibodies in a sample which comprises a plurality of containers, one of said containers being provided with a cap which has antibodies or antigenic or haptenic substances attached to an internal surface thereof, said cap being adapted to be transferred from one to another of said containers so the internal surface thereof is brought into contact with solutions contained in said plurality of containers in a predetermined sequence.
• the "internal surface" of the cap includes those surfaces of the cap themselves which, when the cap is applied to a container, are exposed to the contents of the container, as well as the surfaces of projecting portions provided on the cap to extend within the body of the container when the cap is applied thereto, and surfaces which are physically attached to or retained within a cap which are themselves exposed to the contents of the container when the cap is applied thereto.
• ther "internal surface" of the cap to which the antibodies or antigenic or haptenic substances are attached comprises the internal surface of a tube attached to the cap, for example the tube portion of a "dropper-type” cap having a rubber teat or the like to enable the fluid to be drawn up into the tube and expelled therefrom.
• One of the main limitations of the apparatus disclosed in the prior specification lies in the fact that only a single antibody or antigenic or haptenic substance can be attached to the internal surface of the cap or of the tube attached to the cap. This is a relatively serious limitation when the apparatus is to be used in a screening-type test. For example, in the detection and identification of snake venoms in Australia, it is usually necessary to be able to detect at least two and in most cases five primary snake venoms to enable selection of the appropriate antivenom. This means that when using the apparatus disclosed in the prior specification, at least two and often five separate tests must be carried out in order to identify the unknown venom in the clinical sample, together with control tests where appropriate.
• a device for use in detecting or determining the presence of antigenic or haptenic substances or antibodies in a sample which device comprises a plurality of tubular or capillary elements, each of said capillary elements having antibodies or antigenic or haptenic substances attached to an internal surface thereof, and means for causing fluids to pass simultaneously or sequentially through said plurality of capillary elements.
• fluids including unknown samples and test reagents may be drawn in to the device and hence into contact with the internal surface of each of the capillary elements, and subsequently expelled therefrom.
• such means may comprise a rubber teat or a syringe device.
• the device of the present invention is particularly intended for use with test apparatus of the type generally disclosed in the prior Australian Specifications referred to above.
• the device of the present invention may be provided in combination with a plurality of containers whereby an assay may be performed by bringing the internal surfaces of the capillary elements of the device into contact with solutions contained in said plurality of containers in a predetermined sequence.
• the various test solutions and reagents may be provided in the wells of a reagent tray.
• the capillary elements comprising the device of the present invention may be made of any suitable material such as. glass, polyvinyl chloride, polystyrene or other suitable plastics materials, however it is important that the elements be transparent so that reactions taking place within each element may be observed externally.
• the antibodies or antigenic or haptenic substances may be attached to the internal surface of the capillary elements by known techniques, for example, in the case of glass capillary elements, by adsorption or covalent bonding, and in the case of elements of plastics materials, by adsorption or covalent bonding.
• the capillary elements may be 1.5 cm to 2.0 cm in length, and have an internal diameter of about 1 mm, and an external diameter of about 2 mm. Such elements have a capacity ⁇ f around 5 - 20 ⁇ l.
• the plurality of capillary elements are connected in series by tubular connecting elements.
• fluids such as unknown samples and test reagents are drawn into and expelled from the elements in sequence.
• the tubular connecting elements inter-connecting the individual tubular elements may be of any suitable material, and by way of example, silicone rubber and polyvinyl chloride have bee n found to be suitable materials.
• a device of the present invention enables a single sample to be "screened” against a number of known antibodies or antigenic or haptenic substances in a single test sequence.
• each capillary element will be provided with a different known antibody or antigenic or haptenic substance, and a "positive control" capillary element may also be included in the device.
• a "positive control" capillary element may also be included in the device.
• the device of the present invention may be used in a semi-quantitative type of "screening" test in which a single unknown sample is tested alongside one or more known positive controls against a single antibody or antigenic or haptenic substance in a single test sequence.
• the known positive control or controls may have known levels of the material which is to be detected in the sample, and once again the single test sequence is performed by drawing the various test fluids in sequence into the device and hence into the capillary elements before being expelled therefrom.
• the use of this device in this manner in the performance of digoxin and tetanus screening tests is described below as further examples of the use of this device.
• the present invention relates to an improved method of detecting or determining the presence of antibodies or of antigenic or haptenic substances in a sample.
• Prior Australian Specification No. 68117/81 discloses tests for the detection or determination of the presence of antibodies or antigenic or haptenic substances by an improved enzyme-linked immunosorbent assay procedure in which the enzyme urease is used in the antibody-enzyme conjugate, with urea being the corresponding enzymic substrate utilised to indicate the presence of antibodies or antigenic or haptenic substances in the sample. The presence of ammonia produced by the action of the enzyme urease on the urea substrate is then used to indicate the presence of antibodies or antigenic or haptenic substances in the sample.
• This improved ELISA technique has wide application, not only in connection with the use of the apparatusdisclosed above and in the prior specification, but also as a general ELISA technique for use in association with known apparatus such as plates, wells and the like.
• a method of detecting or determining the presence of antibodies or an antigenic or haptenic substance in a sample by the enzyme-linked immunosorbent assay technique in which the binding of an antibody-enzyme or antigen-enzyme conjugate to a solid phase is used to indicate the presence or absence of antibodies or antigenic or haptenic substance in said sample, characterised in that the enzyme in said conjugate is urease, the solid phase is contacted with urea as the enzyme substrate, and the presence of ammonia is detected or determined using di-bromo-ocresolsulfonphthalein to indicate the presence of antibodies or antigenic or haptenic substances in the sample.
• the present invention may be adapted to perform a wide variety of assay procedures. The following are illustrative, but by no means limiting, of the types of procedures which may be performed:
• A Antigen detection, e.g. hepatitis, digoxin.
• Sandwich antigen assay e.g.
• Solid phase Tube - Anti-hepatitis Ab 2.
• Sample ⁇ Hepatitis subunit or virus
• Type 1 e.g. sheep antibody
• Second Antibody Anti-hepatitis Ab Type 2 Ce.g. rabbit antibody
• a method of detecting or determining the presence of an antigenic or haptenic substance in a sample which comprises, in sequence, the steps of:- 1. contacting the sample with a solid phase having antibody corresponding to the said antigenic or haptenic substance attached thereto, and then contacting the solid phase with an antibodyenzyme conjugate;
• the present invention provides a method of detecting or determining the presence of antibodies in the sample which comprises, in sequence, the steps of:-
• this invention provides a test kit for the detection or determination of the presence of antibodies or an antigenic or haptenic substance in a sample by the enzyme-linked immunosorbent assay technique in which the binding of an antibody-enzyme or antigen-enzyme conjugate to a solid phase is used to indicate the presence or absence of antibodies or antigenic or haptenic substances in said sample, said kit comprising an antibody - enzyme or antigen-enzyme conjugate, the enzyme in said conjugate being urease, and a substrate/ indicator system comprising urea as the enzyme substrate and di-bromo-o-cresolsulfonphthalein as indicator.
• test kits as generally described above may be set up with appropriate components to enable the performance of the wide variety of assay procedures previously mentioned including the so-called “sandwich” and “competitive” assays, and the double-antibody type assays.
• a test kit for the detection or determination of the presence of an antigenic or haptenic substance in a sample comprising, in combination: 1. a solid phase having antibody corresponding to the said antigenic or haptenic substance attached thereto;
• a substrate/indicator system comprising urea as the enzymic substrate and di-bromo-ocresolsulfonphthalein as indicator.
• the invention also provides a test kit for the detection or determination of the presence of antibodies in a sample, said kit comprising, in combination: 1. a solid phase having antigen corresponding to said antibodies attached thereto;
• a substrate/indicator system comprising urea as the enzymic substrate and di-bromo-ocresolsulfonphthalein as indicator.
• the present invention further provides in combination and individually, antibody-enzyme conjugates and substrate-indicator systems, as described above.
• the improvement now provided in these further aspects resides in the use of the particular indicator -di-bromo-o-cresolsulfonphthalein, or Bromcresol Purple, as the indicator of the presence of ammonia.
• the production of ammonia may be readily detected by a pH shift which has been found to be best detected by the vivid colour change (yellow to purple) of Bromcresol Purple incorporated in an unbuffered substrate solution.
• urease-urea as an enzyme-substrate system offers a number of important advantages: the substrate, being stable, may be stored ready to use; titration end points are sharp and readily visible; the enzyme is not poisoned by sodium azide and therefore test reagents may be prepared with this preservative and stored ready to use (this is not the case with Horse
• HRP Radish Peroxidase
• the enzyme reaction may, if desired, be stopped instantly by the addition of the organo- mercurial preservative Thiomersal, thus allowing storage of EIA results for later examination.
• Bromcresol Purple is of particular benefit as an indicator in the methods described above is surprising, since the colour change provided by Bromcresol Purple takes place in the pH range of 5.2 to 6.8.
• Urease has a maximum activity of pH's in the range of 7 to 8. It has, nevertheless, been found that the use of Bromcresol Purple to detect the presence of ammonia is effective in giving a complete and quite rapid colour change. In contrast, other pH indicators tested do not give a comparable colour change or exhibit a similar rapidity of reaction for a given concentration of antigenic substance, for example, snake venom.
• FIG. 1 of the accompanying drawings illustrates the sensitivity of Bromcresol Purple (BCP) as an indicator of the presence of ammonia produced by the action of urease on urea, when compared with the other pH indicators Cresol Red (CR), Bromthymol Blue (BTB), Chlorophenol Red (CPR) and Phenol Red (PR), all of which also provide a colour change in the pH range of 5 to 8, as set out in Table 1 below.
• BCP Bromcresol Purple
• BBP Bromthymol Blue
• CPR Chlorophenol Red
• PR Phenol Red
• Bromcresol Purple is also particularly advantageous when compared with the use of the Nessler reaction to detect the formation of ammonia, as the use of a pH indicator provides a continuous measurement of urease activity and does not destroy the enzyme as in the use of the Nessler reaction. Accordingly, the use of Bromcresol Purple is of particular advantage in performing assays using urease/urea as the enzyme/ substrate system in ELISA techniques.
• this reagent comprises the conjugate carried in a standard diluting buffer, for example, buffered saline (pH 7.2) containing 0.5% by weight, surfactant (Tween 20). 0.25% by weight, bovine serum albumin, and 0.1% by weight, preservative (sodium azide).
• ovalbumin is added to this reagent in an amount of 0.1% by weight or greater, preferably from 0.25% to 1% by weight.
• Figure 2 is a part-sectional view through a first embodiment of a device in accordance with the invention.
• Figure 3 is a part-sectional view of a second embodiment of a device in accordance with the invention.
• the device depicted in Figure 2 is designed particularly for use as a snake venom detection apparatus, and will be described hereinafter with particular reference to its use in this manner.
• the device comprises a glass tube assembly 10, and a syringe 11 which is arranged to draw fluids into and expel fluids from the glass tube assembly 10.
• Assembly 10 comprises six tubular elements 1, 2, 3, 4, 5, 6, which are joined in series by pieces of silicone rubber tubing 8.
• Each of the tubes 1 to 5 has a different antivenom adhering to its internal surface as follows:- Tube 1 Tiger Snake Tube 2 Brown Snake
• tube 6 is provided as a control positive tube.
• the free end of tube 6 is sealed by means of a sealed plastic tube 7 which, in contrast to the transparent tubes 1 to 5, may be coloured, or opaque.
• the device illustrated in Figure 2 of the drawings is used in the detection and identification of snake venoms in combination with a number of solutioncontaining bottles as follows:- Bottle 1 Contains washing buffer Bottle 2 Contains antibody-enzyme conjugate, i.e. antivenom coupled to urease, in buffered saline Bottle 3 Contains washing liquid (unbuffered) Bottle 4 Contains enzyme substrate and indicator, i.e. urea solution,
• the indicator used to detect the production of ammonia in the urease/urea system is Bromcresol Purple.
• this indicator has been found to be of particular benefit in this system and it is found that the detection limit of the test as performed above is approximately 10 to 20 nanograms/ml of sample used in step 2.
• greater sensitivity may be achieved by repeating the test using longer incubations for steps 3 and 6 (for example of the order of 20 to 30 minutes).
• this indicator in the urease/enzyme system is by no means restricted to use with the devices disclosed in the present specification or in the prior specifications referred to above, and those skilled in the art will appreciate that it has wide application as a general indicator for detecting urease activity in ELISA procedures using other apparatus.
• the device described in detail above is not restricted to use in the detection of snake venoms, and it has application in the detection of tetanus antibodies as described in the prior specifications referred to above, as well as in other screening tests utilising the ELISA technique.
• the device depicted in Figure 3 illustrates an alternative embodiment of the device of the invention for use, for example, in a digoxin or tetanus screening test, and will be described hereinafter with particular reference to its use in this manner.
• the device 20 comprises three glass tubular or capillary elements 21, 22 and 23 mounted in a common body or support 24. Each of these elements has a haptenic substance adhering to its internal surface as described below. Support 24 is also provided with three bores 25, 26 and 27 which communicate with elements 21, 22 and 23, respectively. Plungers 28, 29 and 30 are located within bores 25, 26 and 27, respectively, and are adapted to draw fluids through the respective capillary elements and into the bores, and to express these fluids out through the respective elements on movement of the plungers within the bores. Plungers 28, 29 and 30 are interconnected by a single handle piece 31 so that fluids are simultaneously drawn into and expressed from each of the capillary elements 21, 22 and 23.
• a white background area 32 is provided behind a portion of elements 21, 22 and 23 to assist in visual comparison of colour development in these elements.
• the device 20 may be used in a digoxin screening test based on the inhibition of ureaseanti-digoxin antibody conjugate binding to digoxin immobilised on the inner surface of the glass capillary elements caused by free digoxin present in the unknown serum.
• This test may be designed to detect digoxin in the serum of patients at levels below 1.0 nanograms/ml, between 1.0 and 3.0 nanograms/ml, and above 3.0 nanograms/ml.
• the accepted therapeutic range for digoxin is between 1.0 and 3.0 nanograms/ml, serum levels below this range may be ineffective, serum levels above this range may be toxic.
• This simple screening test enables the physician to estimate patient compliance with prescribed medication and, in cases of suspected toxicity, to rapidly confirm the diagnosis.
• the mixtures are expressed out of the elements 21, 22 and 23, the elements are washed and the urea indicator previously described simultaneously drawn into the elements.
• the amount of inhibition of colour development in the case of the unknown sample is then compared to that seen in the cases of the sera containing known amounts of free digoxin to provide a semi-quantitative assay of the unknown sample.
• An alternative use of the device 20 is in a tetanus screening assay in which a sample of the blood or serum of a patient is screened against reference serums or blood to ascertain the level of tetanus antibodies in the sample.
• the assay is based on detection of tetanus antibodies binding to purified tetanus antigen immobilised on the inner surfaces of the glass capillary elements, the procedure comprising incubating the sample serum or blood and high (for example at least 1.28 International Units/ml) and low (for example no greater than 0.01 International
• the sample can be classified into one of three categories: (a) A titre equal to or greater than the high reference titre - indicates patient highly immune and probably does not require booster vaccination (which would possibly involve risk of adverse reaction). (b) A titre between the high and low reference titres
• the urease conjugate is prepared by standard procedures, either by the single step glutaraldehyde method (Aurameas, S., Ternynck, T. and Guesdon, J.L., "Coupling of enzymes to antibodies and antigens", 1978 Scand. J. Immunol. 8 C.Suppl.7 ⁇ , pp. 7 - 23) or by the M.B.S. method (Monji, N., Malkus, H. and Castro, A., "Maleimide derivative of hapten for coupling to enzyme : A new method in enzyme immunoassay" Biochem. Biophys. Res. Comm., 85, 671 (1978)).
• the conjugate reagent is made-up in buffered saline (pH 7.2) as described in detail above, and includes ovalbumin in an amount of from 0.25% to 1% by weight to minimise non-specific binding of the conjugate.
• the substrate solution comprises a dilute urea solution, for example containing 1 mg/ml of urea in glass distilled water, to which is added EDTA to complex heavy metal ions which may poison the urease.

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Cited By (22)

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• 1981
  • 1981-12-15 NZ NZ199286A patent/NZ199286A/en unknown
  • 1981-12-21 CA CA000392770A patent/CA1184847A/en not_active Expired
  • 1981-12-22 DE DE8282900081T patent/DE3176186D1/de not_active Expired
  • 1981-12-22 EP EP82900081A patent/EP0067182B1/en not_active Expired
  • 1981-12-22 JP JP57500157A patent/JPS57502041A/ja active Pending
  • 1981-12-22 WO PCT/AU1981/000191 patent/WO1982002211A1/en not_active Ceased
  • 1981-12-22 AT AT84201067T patent/ATE41528T1/de not_active IP Right Cessation
• 1982
  • 1982-08-12 NO NO822750A patent/NO822750L/no unknown
  • 1982-08-20 DK DK375782A patent/DK158682C/da active
• 1990
  • 1990-01-05 DK DK002590A patent/DK159408B/da not_active Application Discontinuation

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