FIG 8.

Adaptation of D/5920 in DBA/2 mice. Three DBA/2 mice were infected with 10⁵ TCID₅₀ of D/5920. At 4 dpi, mice were euthanized, and nasal turbinates, trachea, and lungs were collected and homogenized. The pure homogenate was used to inoculate three naive DBA/2 mice. After five serial passages, 8 DBA/2 mice were infected intranasally with 30 μl of mouse passage 5 IDV (D/5920-M5). (A) Weight was measured every 2 days, and clinical signs were recorded daily. (B) At 4 dpi, 4 infected mice were euthanized, and different organs were collected. Virus titers were determined using the TCID₅₀ method and are expressed in log₁₀ of TCID₅₀/g of tissue. The dotted line represents the positivity threshold (1.5 log₁₀ TCDI₅₀/g of organ).