Characterization of virologic and histopathological parameters in C57BL/6j mice upon adapted-DENV-3 infection.

<p>(A–D) C57BL/6j mice (n = 6 per group) were inoculated with 10LD₅₀ (1000 PFU) of DENV-3 (i.p) and in the third, fifth or in the seventh day of infection, mice were culled and blood and tissues were collected for the following analysis: (A–C) Viral loads were recovered from the spleen, liver and blood, respectively. Results are shown as the log of PFU per g of tissue or per mL of blood. (D) Shows virus NS1 antigen serum levels by ELISA and expressed as O.D. (E–F) C57BL/6j mice (n = 6 per group) were inoculated with 10LD₅₀ (1000 PFU) of DENV-3 (i.p) and in the seventh day of infection mice were culled and liver collected for the following analyses: (E) Liver was collected, formalin-fixed and processed into paraffin sections. Serial sections from each tissue were stained with anti-DV NS3 antibody E1D8 (NS3) or an isotype control mouse IgG2a, and multiple sections of each tissue type were thoroughly examined for staining. Positive staining for NS3 is brown while hematoxylin counterstain is blue. (F) shows semi-quantitative analysis of hepatic damage and Hematoxylin & Eosin staining of liver sections of control and DENV-3-infected mice, seven days after infection (Scale Bar - 400 µm). The images presented are representative of an animal on the seventh day of infection. In (G) Viral inoculum (10LD₅₀ or 1000 PFU) was heat inactivated (Heat, 56°C, 60 min) or treated with UV light (UV, 15 min) before inoculation in C57BL/6j mice. Lethality was evaluated every 12 hours for 14 days. (H) WT mice (<i>n</i> = 6 mice per group) were pretreated i.p with 100 µL of Anti-DENV-3 antiserum or control serum (pre-immune serum) before inoculation of 10LD₅₀ (1000 PFU) of adapted-DENV-3 (i.p). Lethality was evaluated every 12 hours for 14 days. Results are expressed as % of survival. Results are expressed as mean ± SEM (except for A–C, expressed as median) and are representative of at least two experiments. * for P<0.05 when compared to control uninfected mice. 10 LD₅₀ corresponds to 1000 PFU of adapted-DENV-3. ND- not detected. NI- not-infected. dpi- days post-infection. NC – Negative control. HS – hepatocyte swelling. N – necrosis. D – degeneration. H – hemorrhage. OS – Overall Score.