LIGHT Induces Distinct Signals to Clear an AAV-Expressed Persistent Antigen in the Mouse Liver and to Induce Liver Inflammation

Background: Infection with adeno-associated virus (AAV) vector with liver tropism leads to persistent expression of foreign antigens in the mouse liver, with no significant liver inflammation or pathology. This provides a model to investigate antigen persistence in the liver and strategies to modulate host immunity to reduce or clear the foreign antigen expressed from AAV vector in the liver.

Methods/Principal Findings: We showed that expressing LIGHT with an adenovirus vector (Ad) in mice with established AAV in the liver led to clearance of the AAV. Ad-LIGHT enhanced CD8 effector T cells in the liver, correlated with liver inflammation. LTβR-Ig proteins blocked Ad-LIGHT in clearing AAV. Interestingly, in LTβR-null mice, Ad-LIGHT still cleared AAV but caused no significant liver inflammation.

Conclusions/Significance: Our data suggest that LIGHT interaction with the LTβR plays a critical role in liver inflammation but is not required for LIGHT-mediated AAV clearance. These findings will shed light on developing novel immuno-therapeutics in treating people chronically infected with hepato-tropic viruses.