Respiratory Diseases

Adenovirus Antigen and Antibody Detection Assays

Adenoviruses are a family of DNA viruses that are an important cause of febrile illnesses in young children. They are most frequently associated with upper respiratory tract syndromes such as pharyngitis but can also cause pneumonia and less commonly, gastrointestinal, ophthalmologic, genitourinary, neurologic, and disseminated disease. Most adenoviral diseases are self-limiting, although fatal infections can occur in immunocompromised patients and occasionally in healthy children and adults.

Adenovirus derives its name from its initial isolation from human adenoids in 1953. To date over 50 types have been identified which are immunologically distinct. They are unusually stable to chemical or physical agents and adverse pH conditions, enabling their prolonged survival outside of the body and water. They are spread primarily via respiratory droplets, however they can also be spread by fecal routes. Some people infected with adenoviruses can have ongoing infections in their tonsils, adenoids, and intestines that do not cause symptoms and they can shed the virus for months or years. Most infections with adenovirus result in infections of the upper respiratory tract such as conjunctivitis, tonsillitis, ear infection, or croup. Adenoviruses types 40 and 41 can also cause gastroenteritis. In babies, adenoviruses can cause coughing fits that look almost exactly like whooping cough, viral meningitis or encephalitis. Most people recover from adenovirus infections on their own, although fatal infections can occur in immunocompromised individuals. Diagnosis

ADENOVIRUS MORPHOLOGY

Since adenoviruses are associated with a variety of clinical symptoms and non-specific manifestations, identifying an infection based upon clinical criteria alone is challenging. Laboratory diagnosis can be made using antigen detection, PCR, virus isolation, and serology. Adenovirus typing is usually done by hemagglutination-inhibition and/or neutralization with type-specific antisera or by molecular methods. Mammalian adenoviruses share group-specific antigen epitopes (on the inside of hexons) which are the main antigens involved in the host immune response. By detecting the common hexon antigens, most commercial immunoassays are capable of recognizing the majority of Adenovirus serotypes in nasopharyngeal secretions or stool specimens. Confirmation of adenovirus infection is important in order to decide on the use of antiviral agents, exclude other treatable infections, establish a prognosis, and initiate infection control measures when appropriate.