FIG. 3.

Stability of wt HAV in Huh7 cells. (A) IF analysis of Huh7 cells infected with HAV8Y-Bsd or HAV.WT-Bsd and selected with 2 μg/ml blasticidin for 2 weeks. Mock-infected Huh7 cells grown in the absence of blasticidin were used as a negative control (Control). Cells were grown in eight-well slides and stained with anti-HAV antibodies as indicated in Fig. 2. (B) Titers of HAV8Y-Bsd and HAV.WT-Bsd grown in Huh7 cells were assessed in Huh7 and FRhK-4 cells using the blasticidin resistance endpoint titration assay in the presence of 2 μg/ml blasticidin. Plates were observed under the microscope 7 days after infection, and wells containing surviving cells were counted as positive for the titer determination. The titration was repeated at least three times with similar results, and the values represent one titration. Values are log₁₀ of the HAV titers determined by the Reed and Muench method (35), and the standard deviations are shown as lines.