Quantitation of adenovirus genome during acute infection in normal children

Background: Adenovirus infection causes a wide range of clinical illness in normal children. New molecular techniques allow quantitation of viral genome to study the natural history of adenovirus infection and viral load in normal children. Methods: Clinical samples were collected from 38 previously healthy, febrile children, and viral cultures were performed. Quantitative polymerase chain reaction (PCR) was used to detect adenovirus genome and to determine viral load. Adenovirus isolates were genotyped with a PCR-based assay. Results: Adenovirus culture was positive in 6 children who were diagnosed with acute adenovirus infection. Throat swabs contained high copy numbers of adenovirus genome (1.6 X 10(6)-6 X 10(7) copies/swab) from 4 of 4 adenovirus culture-positive children. Only 2 of 32 adenovirus culture-negative children had detectable adenovirus genome from throat swabs, but with a lower copy number (8 X 10(2) copies/swab). Adenovirus genome was not detected in blood samples from 5 of 6 adenovirus culture-positive children with uncomplicated upper respiratory tract infection and from all adenovirus culture-negative children. High level viremia (1.8 x 10(8)/ml) was detected in an adenovirus culture-positive 6-month-old infant with fever, pneumonia, conjunctivitis and hepatitis. Subsequent reduction in viral load paralleled her clinical recovery. Adenovirus viruria (1 x 10(9) copies/ml) with normal urinanalysis was detected in another adenovirus culture-positive child. All 6 adenovirus isolates were genotyped as adenovirus type 7h. Conclusion: Viral load assessment in clinical samples determined by quantitative PCR can be useful in the diagnosis of adenovirus infection in immunocompetent, febrile children.