Enzyme Linked Immunosorbent Assay And Immunochromatography In The Evaluation Of Anti- Rubella Antibodies
S Sangeetha, P Seema, M Damayanthi
anti-rubella igg antibodies, elisa, immunochromatography
S Sangeetha, P Seema, M Damayanthi. Enzyme Linked Immunosorbent Assay And Immunochromatography In The Evaluation Of Anti- Rubella Antibodies. The Internet Journal of Microbiology. 2012 Volume 10 Number 1.
A new commercially available rapid screening immunochromatographic test (ICT) for Detection of anti-rubella IgG & IgM antibodies was compared with ELISA. Materials and methods: 161 serum samples were tested by immunochromatography card test (Rubella IgG/IgM, SD –Bioline) and were compared with a standard IgG & IgM ELISA (Ani Biotech Oy, Orgenium Laboratories, Vantaa, Finland). Results: ELISA and ICT showed a sensitivity and specificity of 63.4% and specificity of 77% and 36.6% and 22.52% respectively in detection of anti-rubella IgG antibodies .All samples were negative for IgM by both methods. Statistical analysis done using Chi- square test showed a significant difference in sensitivity and specificity between the two tests (p< 0.05). Conclusion: ELISA was superior in achieving a comparatively high sensitivity and specificity. The rapid test required little technical expertise, lesser time and could be done without elaborate equipment unlike the ELISA. If the low sensitivity and specificity of ICT could be corrected in the kit by using better high inbuilt sensitivity & specificity controls for anti-rubella IgG, then it could replace IgG ELISA in screening for rubella antibodies in peripheral laboratories.
Rubella is a mild disease which ordinarily is benign in children and adults. However, if acquired during the first trimester of pregnancy it can damage the developing foetus. For this reason, serological testing to determine the immune status of women of child bearing age is important¬ 1. Non-immune pregnant women are at risk of contracting the infection from patients and unimmunized men2.The detection of IgG antibodies is the only laboratory tool available to assess immune status to rubella virus.
Serological testing is universally used today to determine immune status and acute rubella infection3. ELISA test for rubella is objective, sensitive, specific, and economical. Seroprevalence studies conducted in support of rubella control activities typically use the quantitative detection by EIA of IgG in a single serum sample4.
Recently more rapid, less complicated assays for rubella testing have been developed including Immunochromatography. Terada K
Materials and methods
This study was undertaken in August 2010 after approval by the Institute Ethical committee. 161 purposive serum samples were collected from volunteers of our institute after taking written informed consent. Subjects suspected of having current infection with rubella virus were excluded. A 5ml blood specimen was obtained from each subject. The separated serum was stored at 4-8 0C at the study site. Rubella specific IgG and IgM antibodies were detected by colloidal gold solid-phase Immunochromatography( Rubella IgG and IgM, SD-Bioline) and a commercial IgG enzyme linked immunosorbent assay (ELISA) Rubella IgG & IgM Kit (Ani Biotech Oy, Orgenium Laboratories, Vantaa, Finland) in accordance with manufacturer’s instructions. Statistical analysis was done by Chi-square test.
A total of 161 samples were tested by both methods as shown in Table 1. 130(80.75%) were positive by IgG ELISA, (6 samples showing uncertain results were excluded). 75 (46.58%) were positive by IgG ICT. All samples were negative for IgM antibodies by both techniques.
Table 2 shows the comparison of specificity and sensitivity between the two test procedures. ELISA showed a sensitivity of 63.4% and specificity of 77%. ICT showed a sensitivity of 36.6% and specificity of 22.52%. ELISA showed a high sensitivity and specificity when compared to ICT.
The difference in sensitivity and specificity between the two tests was found to be significant (p< 0.05) by Chi-square test.
The aim of all rubella antibody detection techniques is to get maximum sensitivity with minimum sacrifice of specificity. When large volumes of samples are to be tested, a technique that is simple and fast to perform giving results that are reliable, easily interpreted and cost effective is required1.
In our study IgG rubella ELISA showed 63.4% sensitivity and 77% specificity, this is comparable to Wittenburg
In a study similar to ours, Terada K
ELISA continues to be the gold standard for detection of immunity against rubella. Though it is highly sensitive and specific, it is cumbersome to perform, requires trained technical personnel and reports have long turnaround time. On the other hand, ICT assay is a rapid test has been added to the battery of available rubella tests. This test unlike ELISA requires no pre -treatment of sera, elaborate equipment and can be performed in a matter of minutes. If ICT had high inbuilt sensitivity and specificity controls, as shown by other authors, it could be an acceptable alternative to ELISA. ICT could very well be most useful for clinical laboratories performing tests for where immediate results are required for management of patients.
The authors would like to thank Mr Girish of Standard Diagnostics for providing the ICT cards & ELISA Kit.