Enzyme Immunoassay for the Detection of Herpes Simplex Virus 1, 2 IgM Antibody in Human serum
Introduction
The Herpesviridae family consists of a large number of DNA viruses that are among the most common causes of human infections worldwide. Herpes simplex virus (HSV) infection is caused by two virus types: HSV-1 and HSV-2. HSV-1 primarily causes non-genital lesions, whereas HSV-2 commonly infects the genital organs (Mahy & Van Regenmortel, 2009).
HSV-1 infections are typically associated with non-genital warts (cold sores), affecting lips, gingiva, the mouth, and occasionally the cornea and genital area. These infections often manifest as painful vesicles. Eye infections may cause redness, a sensation of foreign material in the eye, photophobia, and excessive tearing. Transmission occurs through direct person-to-person contact or exposure to infected bodily fluids such as saliva, tears, urine, and feces (Lennette & Smith, 1999). Unhealed vesicles also pose a risk of transmission.
HSV-2 predominantly causes genital lesions in adults and is linked to sexual activity. Symptoms typically appear 4–7 days after exposure and may be asymptomatic in healthy individuals and pregnant women. However, immunocompromised individuals are more susceptible to severe manifestations. HSV-2 infections can lead to small, painful vesicles in the genital area and, in some cases, vaginal secretions in affected females. Neurological involvement may lead to fever, headaches, vomiting, and neck stiffness 3–12 days post-infection (Murray et al., 2021).
Additionally, healthcare workers, including dentists, medical personnel, and laboratory staff, are at higher risk of HSV infection due to potential exposure. Neonatal transmission during childbirth is another critical mode of infection.
Clinical Significance
The detection of HSV-1 and HSV-2 IgM antibodies is crucial in diagnosing acute infections. IgM antibodies appear early in the infection, later declining and being replaced by IgA and IgG antibodies (Kimberlin & Whitley, 2007). Identifying HSV-specific IgM can help in early diagnosis, which is particularly important for immunocompromised individuals, pregnant women, and newborns, as HSV infections in these populations can lead to severe complications such as encephalitis and neonatal herpes.
HSV serological testing is essential in determining recent infections, particularly in cases where clinical symptoms are ambiguous or absent. Detecting IgM antibodies aids in differentiating primary infections from reactivations. Early detection enables timely therapeutic intervention, minimizing complications and reducing transmission risks (Looker et al., 2015).
Test Principle
This assay is based on the indirect ELISA technique. Diluted patient serum samples react with HSV-1 and HSV-2 antigens coated on microtiter wells. After incubation, HRP-conjugated anti-human IgM is added. If anti-HSV-1,2 IgM is present, it binds to the conjugate. A chromogenic substrate is then added, leading to a color change proportional to the IgM concentration. The reaction is stopped with an acid solution, and absorbance is measured at 450 nm.
References
- Kimberlin, D. W., & Whitley, R. J. (2007). Neonatal herpes simplex virus infections. Clinical Microbiology Reviews, 20(1), 1-13.
- Lennette, E. H., & Smith, T. F. (1999). Laboratory Diagnosis of Viral Infections (3rd ed.). Marcel Dekker.
- Looker, K. J., Magaret, A. S., Turner, K. M., Vickerman, P., Gottlieb, S. L., & Newman, L. M. (2015). Global estimates of prevalent and incident herpes simplex virus type 1 infections in 2012. PLoS One, 10(10), e0140765.
- Mahy, B. W. J., & Van Regenmortel, M. H. V. (2009). Desk Encyclopedia of Human and Medical Virology. Academic Press.
- Murray, P. R., Rosenthal, K. S., & Pfaller, M. A. (2021). Medical Microbiology (9th ed.). Elsevier.