FIG 1.

The thrombocytopenia of human platelets and the viral RNA load were detected in dengue virus-infected humanized mice. Twenty-five humanized mice were infected with 1 × 10⁷ PFU Den2/07K2861 virus intravenously (i.v.). Subsequently, the mice were bled at the indicated times (dpi), and the whole blood was used for platelet counting, while the serum was used for viral load measurement. (A) The human platelets dropped significantly after virus infection from 3 dpi to 28 dpi compared with preinfection levels. Ten microliters of humanized mouse whole blood was stained for human CD41 and mouse CD41, and then human and mouse platelets were counted by flow cytometry using fluorescent beads. (B) Viremia was measured by virus-specific qRT-PCR in serum. The serum samples were collected at the indicated times (dpi) and used to extract viral RNA. The data shown are the numbers of viral RNA copies per microliter of serum. The qRT-PCR detection limit was approximately 1,000 copies.