Laboratory Diagnosis - Adenovirus Infections

Laboratory Diagnosis

◗ Specimens

Specimens used depend on the nature of the clinical illness caused by adenoviruses. These include throat swab, nasopha-ryngeal aspirate, bronchial lavage, conjunctival swab, corneal scraping, urine, and feces.

◗ Microscopy

Certain serotypes of enteric adenoviruses may be seen directly in stool specimens by electron microscope. These serotypes (40, 41, 42) are difficult to grow in cell cultures, hence are referred to as noncultivable adenoviruses.

◗ Direct antigen detection

ELISA or direct fluorescent antibody test using specific anti-bodies raised against adenoviruses is used to detect viral anti-gen in feces and nasopharyngeal secretions.

◗ Isolation of the virus

Isolation of the virus by cell culture establishes the specific diagnosis of the condition. Viruses from clinical specimens may be isolated on primary human embryonic kidney cells, HeLa, Hep-2, and KB cells. The viruses within 2–20 days pro-duce a lytic infection with characteristic inclusion bodies. Primary human embryonal kidney cells support growth of many fastidious adenoviruses. The viral antigens in the cell cul-ture can be detected by direct immunofluorescent test using polyclonal or monoclonal antibodies. The viral isolates are usually classified into subgroups by hemagglutination with rat and monkey erythrocytes. Further serotyping is carried out by neutralization test.

◗ Serodiagnosis

Serology is rarely used for diagnosis of the cases. It is usually used for epidemiological studies. They are also used to confirm causative role of a fecal or respiratory tract isolate by identify-ing its serotype.