ENZYME IMMUNOASSAYS FOR THE DIAGNOSIS OF TOXOPLASMOSIS. Toxoplasma gondii INFECTIOUS SEROLOGY. Parasitology

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1 INFECTIOUS SEROLOGY Parasitology ENZYME IMMUNOASSAYS FOR THE DIAGNOSIS OF TOXOPLASMOSIS Toxoplasma gondii ELISA and IMMUNOBLOT kits are optimized and validated for detection of IgA, IgE, IgG and IgM antibodies in human serum and plasma

2 Introduction Toxoplasmosis is a widespread parasitic disease caused by protozoan Toxoplasma gondii a parasite with a complicated life cycle consisting of several morphologically different stadia. Primary hosts are members of the feline family. Humans and most warm-blooded animals can be infected by either primarily infected food (insufficiently heat-treated meat) or by ingestion of oocysts (secondary contaminated food or contaminated fingers, objects, etc.). Acquired toxoplasmosis in immunocompetent individuals is usually asymptomatic or can manifest itself with flu-like symptoms (subfebrility, fatigue, lymphadenopathy, muscle aches) and has no lasting ill effects. Severe life-threatening infections (encephalitis, hepatitis, chorioretinitis, myocarditis, generalized form of the disease) may develop in immunocompromised patients usually because of a reactivation of a latent infection. Congenital toxoplasmosis is caused by transmission of infection from mother to foetus and it might result in severe damages of the foetus (brain calcification, hydrocephalus, vision disorders, mental affections), still birth or abortion. The effects of congenital toxoplasmosis can be prevented by chemotherapy. Diagnosis of infection Diagnosis of the disease is based on epidemiological anamnesis, clinical manifestation and laboratory tests. Direct detection of the parasite is not available for routine diagnostics. Serology is the most important tool for laboratory diagnostics of toxoplasmosis. Screening determination of total antibodies by complement fixation test (CFT) Determination of specific IgA, IgE, IgM, IgG antibodies and IgG avidity by ELISA and confirmation of results by Immunoblot

3 Antibody Response IgG Antibody titer IgE IgG Avidity IgA CFT IgM Months ELISA IgM antibodies: Highly sensitive marker of acute infection Disadvantage: long-time persistence after the beginning of infection (more than 1 year) IgA antibodies: Sensitive and specific marker of acute infection Persistence for -9 months from the beginning of infection IgE antibodies: Highly specific marker of acute infection Persistence up to months from the beginning of infection IgG antibodies: Anamnestic antibodies Persist for years and ensure protection against new infection IgG avidity reflects stage of infection Clinical Application Diagnostics and differentiation of toxoplasmosis stage by detection of IgA, IgE, IgG a IgM specific antibodies in human serum or plasma and determination of IgG avidity. Antigens Purified and inactivated native Toxoplasma gondii antigen (RH strain).

4 Test Principle Summary of EIA Protocol The IgG assay is based on a sandwich type of ELISA method. The IgA, IgE and IgM assays are based on a capture type of ELISA method. Step No. 1 Test steps Dilute samples Serum/plasma (1+1) Sandwich ELISA Capture ELISA 2 Pipette Controls and diluted samples 1 µl Blank = empty well HRP HRP 3 Incubate minutes at 37 C Anti-Hu IgG Tracer 4 Aspirate and wash the wells 5 times Ag 5 Add 1 µl Conjugate or Tracer Blank = empty well IgG IgM Incubate minutes at 37 C 7 Aspirate and wash the wells 5 times Ag Anti-Hu IgM 8 Add 1 µl Substrate (TMB-Complete) Including blank Microtitre plate Microtitre plate Tracer: T.gondii antigen + HRP labelled anti-p3 antibody 9 Incubate 2 minutes at 37 C 1 Add 1 µl Stopping solution Including blank 11 Read colour intensity at 45 nm User Comfort Test Characteristics Ready-to-use components (except Tracer) Colour-coded components Interchangeable components Breakable colour-coded microplate strips CUT-OFF included Semiquantitative evaluation of results (Index of Positivity) Quantitative evaluation of IgG antibodies (IU/ml) Easy assay procedure ELISA Diagnostic Sensitivity Diagnostic Specificity EIA Toxoplasma IgA 9.9% 99.% EIA Toxoplasma IgE 9.9% 99.% EIA Toxoplasma IgG 98.9% 99.2% EIA Toxoplasma IgM 9.4% 97.9%

5 Results Interpretation IgE IgA IgM IgG Interpretation + Acute infection (occurs rarely) Low + Acute infection Acute infection Acute or post-acute infection Advantages Identical assay procedure High diagnostic specificity and sensitivity High reproducibility High dynamics of antibody response Avidity test available Ready for automation Customer support Low Post-acute infection + + Post-acute or latent infection + Latent infection Specific antibodies were not proven IMMUNOBLOT Test Principle Electrophoretically separated Toxoplasma gondii antigens are transferred to a nitrocellulose membrane. E P Reaction of substrate and enzyme resulting in coloured insoluble product Clinical application Detailed determination for the presence of anti-toxoplasma gondii specific antibodies Diagnostic of Toxoplasma gondii infection, confirmative test for ELISA Useful method to trace immune profile of mothers' and newborns sera determination of congenital toxoplasmosis Enzyme-conjugated secondary antibody binding to primary antibody User comfort Ag Specific primary antibody binding to protein Specific antigen protein Blocking agent Strip Non-specific antigen protein Ag Ready-to-use components Colour-coded strips Positive and Negative controls CUT-OFF control is present on the strip Interchangeable components Easy assay procedure Anti-Hu IgG (IgA, IgM): AP-labelled anti-human IgG (IgA, IgM) antibody

6 Antigens Summary of Immunoblot Protocol Antigen with Mw 3 kda is considered as a positivity marker. Step No. Test steps 1 Pipette Universal solution 2 ml Cut-off line Start 2 Strips soaking 1 min. at room temperature 3 Aspirate 4 Dilute samples serum/plasma (8µl+1.5ml) 35 kda 3 kda 5 Pipette Controls and diluted samples 1.5 ml 7 Incubate min. at room temperature Aspirate samples and wash strips with 1.5 ml of Universal solution 3-times for 5 min. 8 Pipette Conjugate 1.5 ml Test Characteristics 9 1 Incubate min. at room temperature Aspirate Conjugate and wash strips with 1.5 ml of Universal solution 3-times for 5 min. Immunoblot Diagnostic Sensitivity Diagnostic Specificity 11 Pipette Substrate solution (BCIP/NBT) 1.5 ml BLOT Toxoplasma IgA 9.9% 92.9% BLOT Toxoplasma IgG 91.7% 91.7% Incubate 1 min. at room temperature Aspirate Substrate solution and wash strips with 2 ml of distilled water 2-times for 5 min. BLOT Toxoplasma IgM 9.9% 99.5% 14 Sticking and evaluation of strips Advantages Easy interpretation and reproducibility of results High diagnostic specificity and sensitivity Easy evaluation of the test Compatibility with all commercial immunoblot processing systems Customer support

7 Clinical Data Seroprevalence and dynamics of IgG antibody in population of blood donors (the Czech Republic) 5 4 Blood donors (n = 483) Antibody titer 3 2 Positive (n = 119) (seroprevalence) Negative (n = 34) 1 Borderline 25% 75% Samples Avidity test Determination of IgG antibody avidity is possible. IA (%) A F G CH I J L M Samples of patients A-M Time interval in month (2-11) from the first testing () sample 2. sample 3. sample 4. sample At the beginning of infection the IgG antibodies have lower avidity (i. e. lower strength of specific bound) than in the latent stage. During the progress of infection the immune response matures and the avidity increases.

8 INFECTIOUS SEROLOGY Ordering Information Related Products ELISA Cat. No. Product No. of Tests TgA9 EIA Toxoplasma IgA (capture) 9 TgE9 EIA Toxoplasma IgE (capture) 9 TgG9 EIA Toxoplasma IgG 9 TgM9 EIA Toxoplasma IgM (capture) 9 Immunoblot Cat. No. Product No. of Tests TgAB1 BLOT Toxoplasma IgA 1 TgGB1 BLOT Toxoplasma IgG 1 TgMB1 BLOT Toxoplasma IgM 1 CFT Cat. No. TgKF2 TgKF5 Tg-KF1 KFAs KFAs1 KFC1 TgKFN2 TgKFP2 Product Toxo CF Ag lyophil. (.2 ml) Toxo CF Ag lyophil. (.5 ml) Toxo CF Ag lyophil. (1 ml) CF AMBOCEPTORset (.5 ml) CF AMBOCEPTORset (1 ml) CF COMPLEMENT (1 ml) Toxo CF Negative control, lyophil. Toxo CF Positive control, lyophil. Contact TestLine Clinical Diagnostics Ltd. Krizikova 8 12 Brno, Czech Republic Tel.: (218) Fax: trade@testlinecd.com Company is certified to the quality management system standards ISO 91 and ISO for in vitro diagnostics.