Previous studies in our laboratory strongly suggested that fibronectin was upregulated by hepatitis B virus (HBV) in HepG2.2.15 cells. Report by Budkowska A also indicated that human liver fibronectin Could bind HBV in a species-restricted manner. Therefore, it is reasonable to ask whether inhibiting fibronectin expression might have anti-HBV activity and whether fibronectin might be developed as a new potential cellular target for anti-HBV drugs. By using fibronectin antisense oligonucleotide (ASODN), fibronectin antibody, and Protocatechuic aldehyde (PA), we were able to show that HBV productions in HepG2.2.15 cell culture were reduced in a dose-dependent manner by fibronectin inhibition. In addition, we found that treatment with ASODNs, fibronectin antibody, and PA did not affect HepG2.2.15 cell viability. Furthermore, we observed that fibronectin inhibition sensitized HBV to anti-HBV drugs. In summary, this study demonstrates that fibronectin is essential for HBV propagation and also provides some evidences for the potential of fibronectin as a new cellular target for HBV infection therapy. (c) 2006 Elsevier Inc. All rights reserved.