Herpes Simplex Antibodies

Herpes simplex virus (HSV), a member of the herpes virus group, causes various clinically severe manifestations, including genital lesions, keratitis or conjunctivitis, generalized dermal lesions, and pneumonia. Severe involvement is associated with intrauterine or neonatal infections and encephalitis; such infections are most severe in immunosuppressed patients. Of the two closely related antigenic types, Type 1 usually causes infections above the waistline; Type 2 infections predominantly involve the external genitalia. Primary contact with this virus occurs in early childhood as acute stomatitis or, more commonly, as an inapparent infection.

Sensitive assays, such as indirect immunofluorescence and enzyme immunoassay, are used to demonstrate immunoglobulin M (IgM) class antibodies to HSV or to detect a fourfold or greater increase in IgG class antibodies between acute- and convalescent-phase sera.

Purpose

• To confirm systemic infections caused by HSV
• To detect recent or past HSV infection

Patient preparation

• Explain to the patient the purpose of the test.
• Tell him that the test requires a blood sample and who will perform the venipuncture and when.
• Reassure him that although he may experience transient discomfort from the needle puncture and the tourniquet, collecting the sample takes less than 3 minutes.

Procedure and posttest care

• Perform a venipuncture, and collect 5 ml of sterile blood in a red-top tube.
• Allow the blood to clot for at least 1 hour at room temperature.
• If a hematoma develops at the venipuncture site, apply warm soaks.

Precautions

• Handle the sample gently to prevent hemolysis.
• Transfer the serum to a sterile tube or vial, and send it to the laboratory promptly.
• If transfer must be delayed, store the serum at 39.2° F (4° C) for 1 to 2 days or at -4° F (-20° C) for longer periods to avoid contamination.

Reference values

Sera from patients who have never been infected with HSV have no detectable antibodies (less than 1 :5).

Abnormal findings

Normal serum values indicating the absence of infection are IgG less than 1:5 and IgM less than 1:10; higher levels are considered positive. The presence of IgM or a fourfold or greater increase in IgG antibodies indicates active HSV infection. Reactivated infections caused by HSV can be recognized serologically only by an increase in IgG class antibodies between acute­and convalescent-phase sera.

Interfering factors

• Hemolysis due to rough handling of the sample
• Failure to store serum at proper temperature