Lab diagnosis of MERS CoV
المؤلف:
Baijayantimala Mishra
المصدر:
Textbook of Medical Virology
الجزء والصفحة:
2nd Edition , p204-205
2025-11-10
30
Samples: Upper respiratory samples such as nasopharyngeal/nasal or throat aspirate or swab are collected. Samples from lower respiratory specimen (bronchoalveolar lavage, tracheal aspirate) are preferred in pneumonia patients. If the patient has trachea intubation, then tracheal aspirate can be collected. However, because collection of lower respiratory specimen usually involves invasive procedure, samples from upper respiratory tract are considered as standard system.
The approach to diagnosis of MERS CoV is in line with SARS CoV. Detection of MERS CoV can be done by RT-PCR, virus isolation, antigen detection and demonstration of four fold rise in antibody titer.
Nucleic acid detection: The commonly used target genes are upstream E gene (upE), orf1a and orf1b. Up E assay is used for screening followed by detection of orf1a or orf1b for confirmation. In case of discrepant result, the sample can be tested for other genes such as N, S or RdRp.
According to WHO criteria, sample positive for two different genes by RT-PCR are considered as positive.
Antibody detection: Four-fold rise in antibody titer in acute and convalescent sample collected 3–4 weeks apart is considered diagnostic. Because of requirement of convalescent sample, this test mainly helps in retrospective diagnosis. Testing of antibody in single serum sample is not recommended.
Antigen detection: Test is used for detection of virus antigen in the affected tissue.
Immunochromatographic test (ICT) showing > 90% sensitivity and specificity has been developed for use in nasal samples of camels.
Virus isolation: MERS CoV can grow in various monkey kidney cell lines such as Vero, LLCMK2. Cytopathic effect showing round refractile cells appears around 5–6 days. The final identification of infected cells is done by RT-PCR.
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