The common species C adenoviruses (serotypes Ad1, Ad2, Ad5, and Ad6) infect more than 80% of the human population early in life. Following primary infection, the virus can establish an asymptomatic persistent infection in which infectious virions are shed in feces for several years. The probable source of persistent virus is mucosa-associated lymphoid tissue, although the molecular details of persistence or latency of adenovirus are currently unknown. In this study, a sensitive real-time PCR assay was developed to quantitate species C adenovirus DNA in human tissues removed for routine tonsillectomy or adenoidectomy. Using this assay, species C DNA was detected in Ficoll-purified lymphocytes from 33 of 42 tissue specimens tested (79%). The levels varied from fewer than 10 to greater than 2 ؋ 10 6 copies of the adenovirus genome/10 7 cells, depending on the donor. DNA from serotypes Ad1, Ad2, and Ad5 was detected, while the rarer serotype Ad6 was not. When analyzed as a function of donor age, the highest levels of adenovirus genomes were found among the youngest donors. Antibody-coated magnetic beads were used to purify lymphocytes into subpopulations and determine whether viral DNA could be enriched within any purified subpopulations. Separation of T cells (CD4/8-expressing and/or CD3-expressing cells) enriched viral DNA in each of nine donors tested. In contrast, B-cell purification (CD19-expressing cells) invariably depleted or eliminated viral DNA. Despite the frequent finding of significant quantities of adenovirus DNA in tonsil and adenoid tissues, infectious virus was rarely present, as measured by coculture with permissive cells. These findings suggest that human mucosal T lymphocytes may harbor species C adenoviruses in a quiescent, perhaps latent form.The common adenovirus serotypes of species C (Ad1, Ad2, Ad5, and Ad6) cause roughly 5% of symptomatic upper respiratory tract (5) and 15% of lower respiratory tract (3) infections in children younger than 5 years.

Although species C human adenoviruses establish persistent infections, the molecular details of this lifestyle remain poorly understood. We previously reported that adenovirus DNA is found in human mucosal T lymphocytes in a noninfectious form (

Adenovirus encodes multiple gene products that regulate proapoptotic cellular responses to viral infection mediated by both the innate and adaptive immune systems. The E3-10.4K and 14.5K gene products are known to modulate the death receptor Fas. In this study, we demonstrate that an additional viral E3 protein, 6.7K, functions in the specific modulation of the two death receptors for tumor necrosis factor-related apoptosisinducing ligand (TRAIL). The 6.7K protein is expressed on the cell surface and forms a complex with the 10.4K and 14.5K proteins, and this complex is sufficient to induce down-modulation of TRAIL receptor-1 and -2 from the cell surface and reverse the sensitivity of infected cells to TRAIL-mediated apoptosis. Down-modulation of TRAIL-R2 by the E3 complex is dependent on the cytoplasmic tail of the receptor, but the death domain alone is not sufficient. These results identify a mechanism for viral modulation of TRAIL receptor-mediated apoptosis and suggest the E3 protein complex has evolved to regulate the signaling of selected cytokine receptors.

Formalin-fixed intestinal tissue specimens from 12 Mexican pediatric patients with intussusception were examined for the presence of adenovirus. Four patients (33%) had detectable adenovirus antigen in epithelial cells as determined by using immunohistochemical analysis. Two of the patients with positive immunohistochemical results had antigens in dendritic and mononuclear inflammatory cells, and 3 patients had positive results for species C adenovirus by in situ hybridization using adenovirus species-specific probes (A-F). A real-time polymerase chain reaction assay specific for species C (nonenteric) adenoviruses was used to confirm immunohistochemical results and to amplify adenovirus DNA for sequencing. A sequence similar to that for adenovirus serotype 1 was found in 1 patient, serotype 2 in another, and serotype 6 in a third; in the fourth patient, the sequence was indeterminate between serotypes 2 and 6. The assays used in this study proved useful for the identification of species C adenoviruses in formalin-fixed specimens from Mexican pediatric patients with intussusception.

Human group C adenoviruses cause an acute infection in respiratory epithelia and establish a long-term or persistent infection, possibly in lymphocytes. The mechanism by which this persistence is maintained is unknown; however, it would require that persistently infected lymphocytes not be deleted. The adenovirus genome encodes proteins that prevent the immune system from eliminating the virus-infected cell, including the E3 receptor internalization and degradation (