Comparison of ELISA with virus isolation for the diagnosis of genital herpes

Rapid detection, culture-amplification and typing of herpes simplex viruses by enzyme immunoassay in clinical samples

BACKGROUND

The laboratory diagnosis of herpes simplex infection may require rapid (direct) tests, as well as cell cultures, for detection of the virus in clinical samples. The quantity of virus present in clinical samples is variable and this may depend on the period from onset of rash. In addition, not all patients may show obvious symptoms with this infection. The successful culture of herpes simplex virus requires prompt transportation after collection of the specimen as the virus is easily inactivated. Hence, rapid and culture tests would enable detection of non-viable and viable viruses.

STUDY DESIGN

We describe the rapid detection of HSV by EIA directly in various clinical samples using commercially available polyclonal sera. In addition specimens were inoculated in microwell cell cultures and 4 days post inoculation the culture fluids were tested for HSV and subtyped by a similar EIA (culture amplified EIA).

RESULTS

The direct EIA showed an endpoint detection of 100 TCID50/ml, sensitivity of 92% (all specimen types) and specificity of 100%. The direct EIA sensitivity was 97% in non-genital specimens and 88% in genital specimens. The culture amplified EIA showed a sensitivity of 95% compared to all confirmed HSV positive samples.

CONCLUSIONS

The results of the HSV rapid tests were available within 24 h from receipt of specimens. Specimens which were culture negative/direct EIA positive were confirmed by blocking antisera. Culture positive specimens which were direct EIA negative were confirmed by subtyping of the virus.

Transport of viral specimens

The diagnosis of viral infections by culture relies on the collection of proper specimens, proper care to protect the virus in the specimens from environmental damage, and use of an adequate transport system to maintain virus activity. Collection of specimens with swabs that are toxic to either virus or cell culture should be avoided. A variety of transport media have been formulated, beginning with early bacteriological transport media. Certain swab-tube combinations have proven to be both effective and convenient. Of the liquid transport media, sucrose-based and broth-based media appear to be the most widely accepted and used. Studies on virus stability show that most viruses tested are sufficiently stable in transport media to withstand a transport time of 1 to 3 days. Some viruses may withstand longer transport times. In many cases, it is not necessary to store virus specimens in a refrigerator or send them to the laboratory on wet ice or frozen on dry ice. However, the specimen should not be exposed to environmental extremes. Modern viral transport media allow for more effective use of viral culture and culture enhancement techniques for the diagnosis of human viral infections.

Sandwich enzyme immunoassay and latex agglutination test for herpes simplex virus keratitis

We determined the in vitro sensitivities and the diagnostic efficacies of a commercially available latex agglutination test and an enzyme-linked immunosorbent assay using a rabbit model of herpes simplex virus type 1 dendritic keratitis. In contrast to the latex agglutination test, the HERPCHEK enzyme-linked immunosorbent assay offers an extremely sensitive and reliable means of laboratory diagnosis of experimental herpes simplex virus keratitis and is more rapid than viral isolation in tissue culture.

Rapid diagnosis of common sexually transmitted diseases in adolescents: a review

Sexually transmitted diseases (STDs) represent a significant health problem for adolescents in the United States. As a result, clinicians from a number of disciplines, among them pediatrics and dermatology, may be called on to evaluate teenage patients with these infections. Traditionally, the diagnosis of many STDs has relied on isolation of the causative organisms in culture. While such procedures typically offer optimal diagnostic accuracy, they are often time consuming and expensive, and may not be widely available. In an attempt to remedy this, culture-independent techniques have been developed to permit more rapid and economical diagnosis of these important pathogens. The strengths and limitations of these methods must be understood, however, for the tests to be used effectively.

Rapid amplified enzyme linked immunosorbent assay evaluated for detecting herpes simplex virus

A new amplified enzyme linked immunosorbent assay (amplified ELISA) kit for detecting herpes simplex virus (HSV) antigen was evaluated. Duplicate swabs were taken from 180 patients with clinically suspected herpes lesions. Tests were performed on a direct swab extract and viral transport medium containing a swab. Of the 93 culture positive specimens, 78 of the extracted samples (sensitivity 83.9%) and 72 of the swabs in transport medium (sensitivity 77.4%) were positive by amplified ELISA. A higher sensitivity (49/54, 90.7%) was obtained when the extracted swab was taken first. In early lesions the sensitivity was 93.8% but in late lesions it was 73.3%. This ELISA therefore offers an alternative to culture for early lesions, but culture is the method of choice for differential diagnosis of genital ulceration. As the specificity was 94.3%, this test is acceptable for testing populations with a high prevalence of HSV infection, but culture should be used for screening populations in which the disease is rare.

Evaluation of a shell vial centrifugation method for the detection of herpes simplex virus

A MRC-5 shell vial method was compared to a MRC-5 conventional tube cell culture method in 410 specimens, 88 of which were positive for herpes simplex virus. The shell vial had a sensitivity of 92% and a specificity of 99% when compared to conventional cell culture.

Evaluation of a rapid latex slide agglutination test for herpes simplex virus as a specimen screen and culture identification method

A total of 449 clinical specimens and 199 culture fluids were tested using the Virogen Herpes Slide Test (Wampole Laboratories, Div. Carter-Wallace, Inc., Cranbury, N.J.), a rapid latex agglutination procedure. The results were compared with those obtained with isolation of herpes simplex virus in cell culture followed by identification using immunoperoxidase or fluorescent reagents. The sensitivity, specificity, and positive and negative predictive values of the direct test were 49.7, 93.4, 96.0, and 37.1%, respectively. The sensitivity and specificity of the latex agglutination test for culture confirmation were 75.9 and 100%, respectively.

Herpes simplex virus detection by ELISA: effect of enzyme amplification, nature of lesion sampled and specimen treatment

The relative sensitivity of two enzyme detection procedures was investigated in a simultaneous "monoclonal" ELISA for herpes simplex virus (HSV). A cyclical enzyme amplified detection system with alkaline phosphatase, rather than horse-radish peroxidase and a conventional chromogenic substrate, gave an increase in absolute sensitivity and a 20 to 30% increase in the detection of HSV in routine isolation-positive genital specimens collected in transport medium. The HSV detection rate, with both procedures, was shown to vary with the site and clinical stage of lesion sampled; it was highest with penile vesicular lesions. Direct extraction of the swab specimen in a small volume of diluent further increased the sensitivity of antigen detection giving positive and negative predictive values of 100 and 96% respectively. The overall sensitivity of HSV detection was equivalent to that obtained by isolation in cell culture. The amplified ELISA offers an alternative, rapid, simple, non-culture technique for routine HSV diagnosis that does not rely upon retention of virus viability.