Figure 1.
Illustration of experimental methods.
A: The flow direction and the division of the hydroxyapatite (HAp) column into 3 parts. After removing the HAp particles from the column, HAp particles were collected in each part of the column. Column head: lower position of the column (upstream side); Mid-column: middle position of the column; Column end: upper position of the column (downstream side). B: Virus elution and incubation processes of HAp columns. Detailed conditions are described in the Materials and methods, section 3–6.
Figure 2.
HAp chromatogram of dengue virus culture fluids from 3 different elution processes.
The solid line is the UV absorbance at 280 nm, the broken line is the UV absorbance at 260 nm, and the dashed line is the conductivity of the elution. The shaded histogram indicates the hemagglutination unit of each fraction. Column A: No elution; Column B: 10–207 mM NaPB (pH 7.2) gradient elution; Column C: 10–600 mM NaPB (pH 7.2) gradient elution. C-1: Admixture proteins peak; C-2: Virus peak.
Figure 3.
SEM images of control HAp surfaces. A: Untreated HAp particles; B: HAp particles after loading of cell culture fluid (virus-free).
Figure 4.
Observation of HAp surfaces that were used in the 3 different elution processes.
Column A: No elution; Column B: 10–207 mM NaPB (pH 7.2) gradient elution; Column C: 10–600 mM NaPB (pH 7.2) gradient elution. Each column was divided into 3 sections (Column end, Mid-column, Column head). The white triangles indicate dengue viruses.
Table 1.
The average number of dengue viruses that were observed in the SEM images.
Figure 5.
Observation of HAp surfaces that were incubated under 3 different conditions.
Column D: no incubation; Column E: incubated at 2°C for 7 days; Column F: incubated at 37°C for 7 days. HAp particles of the column head were observed with scanning electron microscopy. The white triangles indicate spherical-shaped viruses. The black triangles indicate flat-shaped viruses.
Table 2.
The average number of dengue viruses that were observed and counted separately as spherical viruses and flat viruses on the SEM images.