Figure 1.

Classical swine fever (CSF) virus titer after sample treatment performed for virus inactivation. (A) Four infectious cell culture supernatants (two highly virulent strains, CSF0947 and CSF0634, as well as two moderately virulent strains, CSF0902 and CSF0104) and (B) four infectious serum samples were used for the experiment. The samples were 1:2 diluted in phosphate buffered saline (PBS)-Tween₂₀ and incubated at 56 °C for 30 min. Two PBS controls were included; for the first, the samples were 1:2 diluted in PBS and incubated at 56 °C for 30 min (PBS + heat (H) control), whereas the second control was not treated with heat (PBS control). The four serum samples were treated with different Tween₂₀ concentrations (0.05%, 0.1%, 0.3%, 0.5%, 1%, and 2%), whereas one concentration (0.05%) was used for the inactivation of infectious cell culture supernatants. Immediately after treatment, the samples were titrated. The experiment was performed in three independent runs. H = heat treatment at 56 °C for 30 min; T = Tween₂₀.