Enzyme Immunoassay for the Detection of Cytomegalovirus (CMV) IgM Antibody
Introduction
Cytomegalovirus (CMV) infection is widely prevalent and is one of the most common causes of morbidity in humans. CMV is a large double-stranded DNA virus, known for having the largest genome among the Herpesviridae family. A key feature of CMV infection is its ability to establish latent infections with periodic reactivation. While most CMV infections are asymptomatic, the virus can persist in various human organs such as the kidneys, heart, and peripheral blood mononuclear cells for years. Viral shedding occurs for months after primary infection via bodily fluids, including saliva and urine (Mahy & Meulen, 2005).
In immunocompromised individuals, such as bone marrow transplant recipients, CMV can cause severe complications, including interstitial pneumonitis, a major cause of mortality. Similarly, in HIV-positive patients, CMV infection manifests as a disseminated disease (Lennette & Smith, 1999). Congenital CMV infection can lead to serious complications, including hepatosplenomegaly, microcephaly, and mental retardation. Consequently, early and accurate diagnosis of CMV, particularly during pregnancy, is crucial (Connie & Manuselis, 2000).
Serological detection of CMV-specific IgM is a key diagnostic tool. The presence of CMV IgM antibodies suggests recent infection and is an essential component of CMV diagnosis (Major et al., 2001).
Clinical Significance
Detection of CMV IgM antibodies is clinically significant in identifying primary CMV infections. It is especially useful for:
- Pregnant Women: Early detection helps in assessing the risk of congenital CMV transmission and fetal complications.
- Immunocompromised Patients: CMV reactivation in organ transplant recipients and individuals with HIV/AIDS requires timely intervention.
- Neonatal Screening: Congenital CMV infections can cause severe developmental disorders; early diagnosis facilitates timely medical intervention.
- Differentiation from Other Viral Infections: CMV infection can mimic infectious mononucleosis caused by Epstein-Barr Virus (EBV); IgM detection assists in differential diagnosis.
Test Principle
The CMV IgM ELISA kit is based on an antibody capture ELISA technique. Microplate wells are coated with anti-human IgM antibodies. Diluted patient serum samples are added to the wells, allowing IgM molecules to bind to the coated antibodies. After washing, CMV antigen conjugated with horseradish peroxidase (HRP) is added, which binds to the CMV-specific IgM antibodies. A chromogenic substrate is then introduced, and after incubation, color development occurs. The reaction is stopped with a stop solution, and absorbance is measured at 450 nm. The intensity of the color is proportional to the CMV IgM concentration in the sample.
References
- Mahy, B. W. J., & Meulen, V. T. (2005). Topley and Wilson’s Microbiology and Microbial Infections: Virology (10th ed.). Hodder Arnold.
- Lennette, E. H., & Smith, T. F. (1999). Laboratory Diagnosis of Viral Infections (3rd ed.). Marcel Dekker.
- Connie, R. M., & Manuselis, G. (2000). Textbook of Diagnostic Microbiology (2nd ed.). W.B. Saunders.
- Major, M. E., Rehermann, B., & Feinstone, S. M. (2001). Fields Virology (4th ed.). Lippincott Williams & Wilkins.