Abstract
Purpose: :
Epidemic keratoconjunctivitis (EKC) is a highly contagious disease caused by human adenovirus (HAdV) serotypes 8, 19, and 37, and is characterized by acute keratoconjunctivitis and delayed onset, corneal subepithelial infiltrates. Inflammation after adenoviral gene therapy and in clinical HAdV infections may occur independently of viral replication. This study was designed to determine if an ocular HAdV would induce keratitis in the mouse, despite an absence of viral replication.
Methods: :
C57BL/6J mice, aged 8–12 weeks, were injected with various concentrations of cesium chloride gradient–purified HAdV–37 or buffer into their corneal stroma, using a gas powered micro–injection system. Mice were examined for signs of corneal inflammation, and the expression of chemokine/cytokine mRNA and protein in the cornea determined by real–time PCR and multiplex cytokine analysis respectively. Infiltrating cells were characterized by immunohistochemistry of harvested corneas at select times post–infection.
Results: :
Mice injected with 105 TCID of HAdV–37 developed corneal stromal opacities beginning 1 day after injection. Opacities peaked by 3–4 days post–infection, but persisted for up to one month. Buffer–injected corneas remained clear. By real–time PCR, mRNAs for IL–6 and KC were elevated over buffer–injected controls by 4 hours post–infection (3.12 +/– 0.85 and 3.04 +/– 0.39 fold–elevated, respectively) At the same time point, we detected adenoviral mRNAs for E1A and E1B 19k, but not IIIa. Immunohistochemistry performed 4 days post–infection revealed patchy infiltration of neutrophils in the subepithelial corneal stroma and a few scattered CD3–positive cells only in HAdV–37 injected corneas.
Conclusions: :
We describe a new mouse model of HAdV–37 keratitis that will allow us to study host mechanisms for innate immune responses to infection in the absence of viral replication.
Keywords: adenovirus • keratitis • cornea: stroma and keratocytes