FIG. 4.

Overexpression of cyr61 promotes viral growth in HeLa cells infected with CVB3. (A) cyr61 was overexpressed in HeLa cells (cyr61-HeLa) by transfection with the cyr61 gene in pCA, and cell lysates were harvested 48 h after transfection. Controls were HeLa cells transfected with pCA as the vehicle. Tubulin was used as an internal control. (B) HeLa cells transiently overexpressing cyr61 were infected with CVB3 (MOI = 10 and 1) for 1 h and washed twice with PBS, and then cell lysates were harvested at indicated times postinfection (pi). VP1 protein production indicates CVB3 replication and growth. Tubulin was used as an internal control. (C) Each bar represents the mean VP1 content (after normalization to tubulin) at 6 h postinfection in HeLa cells infected with CVB3 (MOI = 10). The VP1 content in controls is expressed as 100% and compared with the percentage converted by the VP1 expression of cyr61-HeLa cells. (D) Viral titers in culture medium from the control and from cyr61-HeLa cells after CVB3 infection (MOI = 10) were compared. Viral titration in the extracellular space was performed by plaque assay (see details in Materials and Methods). The results shown are the averages of three independent assays, with error bars representing the standard deviations.