In vitro growth characterization of the 780032I strain isolated from Crotalus lepidus . A) The growth of the 780032I strain results in lysis of infected Vero cells and in the subsequent formation of plaques in a cell monolayer overlayed with 1% agarose containing growth medium. Plaques can be visualized with crystal violet staining after cells are fixed with formaldehyde. B) The virus titers of the 780032I strain produced by the Vero cells. The cell monolayers were infected with MOI=0.01 and virus titer was measured at different time points by plaque assay. The titers shown are expressed as the mean from two independent experiments performed in duplicate.