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Unit Code 9570:
Respiratory Syncytial Virus (RSV) Antigen

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Useful For

Rapid identification of patients with RSV viral infections

Clinical Information

Acute respiratory disease caused by RSV is a particularly
debilitating infection in infants and young children. The usual
manifestations are upper respiratory disease with rhinitis and fever,
which often progress to bronchiolitis, pneumonia, or both in primary
infections, especially in infants <6 months of age. Hospitalization
is considered early in the course of the disease in infants at risk
for severe RSV infections, such as infants with congenital heart
disease or bronchopulmonary dysplasia.

 

The conventional method of laboratory diagnosis of RSV infection

has been the inoculation of cell cultures, with detection of characteristic

cytopathic effects after several days incubation (range, 3-14 days).

The efficiency of this method of laboratory diagnosis is hampered

by the lability of the virus in transit to the laboratory and the lack of

sensitivity of most cell lines to productive infection with the virus.

 

Direct testing for RSV antigen is rapid, sensitive, and specific when

compared to cell culture methods. With the availability of ribavirin

therapy for serious RSV infections, rapid diagnostic tests for this

virus have become increasingly important.

Reference Values

Negative

Interpretation

Compared to tissue culture, the sensitivity of the RSV antigen assay

is 93% to 97% and the specificity is 90% to 97%.

Cautions

The etiology of respiratory infection caused by microorganisms

other than RSV will not be established with this test.

 

This assay is capable of detecting both viable and nonviable

RSV particles.

 

Test performance depends on antigen load and may not correlate

with tissue culture performed on the same specimen.

 

It has been previously established that fresh specimens are

preferable to frozen for RSV testing. Suboptimal test performance

may result with the latter. Fresh specimens should be transported

to the laboratory as rapidly as possible. Specimens may be stored

at 2 to 8 degrees C for up to 48 hours, or -20 degrees C for up to 1

week prior to processing.

 

Inadequate specimen collection, improper specimen handling or

transport, or low levels of virus shedding may yield a false-negative

result. Accordingly, a negative test result does not eliminate the

possibility of an RSV infection. Patient diagnosis should always

include laboratory test results in concert with all other clinical

information available.

 

The rate of positivity observed will vary, depending on the method

of specimen collection, handling/transport system employed, time

of year, age of the patient, geographic location, and, most importantly,

local disease prevalence.

 

Throat swabs are not recommended.

 

Excessively mucoid specimens may fail to be absorbed into the

test membrane or may yield uninterpretable results.

Clinical Reference

1.   Tristram DA,  Welliver RC:  Respiratory syncytial virus.

      In Manual of Clinical Microbiology. 7th edition. Edited by PR Murray.

     ASM Press, Washington DC, 1999,

      pp 942-950

 

2.   Falsey AR, Walsh EE:  Respiratory syncytial virus infection in adults.  

      Clin Microbiol Rev 2000;13:371-384

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