Serological diagnosis of infections due to measles and rubella viruses is done by IgM detection. The aim of this study was to comparatively evaluate commercial systems for detecting IgM against both viruses, including those of ELISA, in indirect and capture formats, chemiluminescence and electrochemiluminescence.
MethodsSeven (for rubella) and six (for measles) assays were studied. One hundred and sixty two samples were included in the study (from 90 rubella and 72 measles cases), and all were analyzed in all the assays.
ResultsThe ranges of sensitivity, specificity and agreement for rubella were 94.8–100%, 52.4–100% and 75.5–98.1%, respectively. The corresponding ranges for measles assays were 87.0–100%, 53.3–100%, and 73.0–99.4%.
ConclusionThe best-performing assays were chemiluminescence (for measles and rubella IgM), and electrochemiluminescence (for rubella IgM).
El diagnóstico serológico de las infecciones por los virus de la rubéola y del sarampión se realiza por detección de IgM específica. El objetivo de este estudio fue evaluar comparativamente sistemas comerciales para la detección de IgM frente a ambos virus, incluyendo ensayos de ELISA, tanto con metodologías indirectas como de captura, así como quimioluminiscencia y electroquimioluminiscencia.
MétodosSe estudiaron 7 ensayos para rubéola y 6 para sarampión. Se emplearon 162 muestras (de 90 casos de rubéola y de 72 de sarampión) que se analizaron en todos los ensayos.
ResultadosLos rangos de sensibilidad, especificidad y concordancia para los ensayos de rubéola fueron 94,8-100%, 52,4-100% y 75,5-98,1%, respectivamente. Los rangos correspondientes para los ensayos de sarampión fueron 87-100%, 53,3-100% y 73-99,4%, respectivamente.
ConclusiónLos mejores ensayos fueron quimioluminiscencia (para IgM frente a rubéola y a sarampión) y electroquimioluminiscencia (para IgM frente a rubéola).
Rubella and measles infections are usually diagnosed in the laboratory by RT-PCR detection of the virus genomes during the first four days of the disease. However, samples taken at the appropriate time for making a direct diagnosis are not always available, so the detection of IgM-class antibodies is used as a fundamental tool for correct case characterization.1 Using a combination of the two approaches greatly improves the performance of measles2,3 and rubella2 diagnosis. In a situation of elimination, such as the current one, serological tests with good sensitivity and specificity characteristics are required. Siemens Healthcare Diagnostics (Marburg, Germany) (ELISA-Siemens) currently supplies the reference methods (ELISA assays, Enzygnost®) for determining IgM against rubella (RuV) and measles (MeV) viruses. The Enzygnost® kits have been used by a large number of network laboratories for many years.4,5 However, they will soon be withdrawn from the market, so the identification of alternative methods with acceptable performance characteristics is a challenge for clinical laboratories.
The aim of this study is to assess the operating characteristics of ELISA assays, based on indirect or μ chain capture methodologies, and chemiluminescence (CLIA) (capture), all for the purpose of determining the levels of IgM against RuV and MeV, and of electrochemiluminescence (ECLIA) (capture), for determining IgM versus RuV. Seven assays were compared for RuV IgM and six for MeV IgM.
Materials and methodsSerological methodsThe following assays were studied (Table 1):
- 1.
Rubella assays
- i.
Enzygnost Rubella IgM, Siemens (Marburg, Germany) (RuV-ELISA-Siemens). The determinations were carried out in a Behring ELISA Processor III (BEPIII) (Siemens).
- ii.
Serion ELISA Classic Rubella IgM, Serion (Würzburg, Germany) (RuV-ELISA-Serion). The determinations were done in a BEPIII.
- iii.
Anti-Rubella IgM ELISA, EuroImmun (Lübeck, Germany) (RuV-ELISA-Euroimmun-1). The assay was done manually, and the plates were read in a BEPIII.
- iv.
Anti-Rubella IgM GP ELISA, EuroImmun (RuV-ELISA-Euroimmun-2). The tests were done manually, and the plates were read in a BEPIII.
- v.
Enzywell Rubella IgM, Diesse (Monteriggioni, Italy) (RuV-ELISA-Diesse). The tests were done manually, and the plates were read in a BEPIII.
- vi.
LIAISON® Rubella IgM, Diasorin (Saluggia, Italy) (RuV-CLIA). The determinations were done on a LIAISON® XL platform (Diasorin).
- vii.
ELECSYS® Rubella IgM, Roche Diagnostics (Penzberg, Germany) (RuV-ECLIA). The determinations were done in a Cobas e411 analyzer (Roche Diagnostics).
- 2.
Measles assays
- i.
Enzygnost Measles IgM, Siemens (MeV-ELISA-Siemens). The determinations were carried out in a BEPIII.
- ii.
Serion ELISA Classic Measles IgM, Serion (MeV-ELISA-Serion). The determinations were carried out in a BEPIII.
- iii.
Anti-Measles IgM ELISA, EuroImmun (MeV-ELISA-Euroimmun-1). The tests were done manually, and the plates were read in a BEPIII.
- iv.
Anti-Measles IgM NP ELISA, EuroImmun (MeV-ELISA-Euroimmun-2). Tests were done manually, and the plates were read in a BEPIII.
- v.
Enzywell Measles IgM, Diesse (MeV-ELISA-Diesse). Tests were done manually, and the plates were read in a BEPIII.
- vi.
LIAISON® Measles IgM (Diasorin) (MeV-CLIA). The determinations were done on a LIAISON® XL platform.
List of assays analyzed.
Assay | Manufacturer | Method | Platform/manually | Antigen | Format (no. samples) | Stability once opened | Samples tested (n) |
---|---|---|---|---|---|---|---|
Rubella | |||||||
Enzygnost Rubella IgMRuV-Siemens | Siemens | Indirect ELISA | BEPIII | Rubella-infected BHK21 cells | 96 | Expiry date | 162 |
ELISA Classic Rubella IgMRuV-Virion | Virion | Indirect ELISA | BEPIII | Rubella-infected cells (HPV-77) | 96 | Expiry date | 162 |
Anti-Rubella IgM ELISARuV-Euroimmun-1 | Euroimmun | Indirect ELISA | Manually | Rubella-infected Vero cells (strain HPV-77) | 96 | Expiry date | 162 |
Anti-Rubella IgM GP ELISARuV-Euroimmun-2 | Euroimmun 2 | Indirect ELISA | Manually | Highly purified native GP (strain HPV-77, grown in Vero cells) | 96 | Expiry date | 162 |
Enzywell Rubella IgMRuV-Diesse | Diesse | Capture ELISA | Manually | Purified rubella virus | 96 | Expiry date | 162 |
LIAISON® Rubella IgMRuV-CLIA | Diasorin | Capture CLIA | LIAISON® XL | Rubella viral particle (strain HPV 77) | 100 | 8 weeks | 158 |
Elecsys® Rubella IgMRuV-ECLIA | Roche | Capture ECLIA | Cobas e411 | Rubella-like particles | 100 | 14 days | 160 |
Measles | |||||||
Enzygnost Measles IgMMeV-Siemens | Siemens | Indirect ELISA | BEPIII | Measles-infected Vero cells | 96 | Expiry date | 162 |
ELISA Classic Measles IgMMeV-Virion | Virion | Indirect ELISA | BEPIII | Measles-infected cells, strain Edmonston | 96 | Expiry date | 162 |
Anti-Measles IgM ELISAMeV-Euroimmun-1 | Euroimmun | Indirect ELISA | Manually | Measles-infected cells, strain HNT-PI Vero cells | 96 | Expiry date | 162 |
Anti-Measles IgM NP ELISAMeV-Euroimmun-1 | Euroimmun 2 | Indirect ELISA | Manually | Recombinant NP expressed in eukaryotic cells | 96 | Expiry date | 162 |
Enzywell Measles IgMMeV-Diesse | Diesse | Capture ELISA | Manually | Purified measles virus |