Histopathological and ultrastructural aspects of mice lungs experimentally infected with dengue virus serotype 2

Histological and ultrastructural alterations in lung tissue of BALB/c mice infected with dengue virus serotype 2 (non-neuroadapted), by intraperitoneal and intravenous routes were analyzed. Lung tissues were processed following the standard techniques for photonic and electron transmission microscopies. Histopathological and ultrastructural studies showed interstitial pneumonia, characterized by the presence of mononuclear cells. In the mouse model, the dengue virus serotype 2 seems to led to a transient inflammatory process without extensive damage to the interalveolar septa, but caused focal alterations of the blood-exchange barrier. Endothelial cells of blood capillaries exhibited phyllopodia suggesting activation by presence of dengue virus. Morphometrical analysis of mast cells showed an expressive increase of the number of these cells in peribronchiolar spaces and adjacent areas to the interalveolar septa. Alveolar macrophages showed particles dengue virus-like inside rough endoplasmic reticulum and Golgi complex, suggesting viral replication. The tissue alterations observed in our experimental model were similar to the observed in human cases of dengue fever and dengue hemorrhagic fever. Our results show that BALB/c mice are permissive host for dengue virus serotype 2 replication and therefore provides an useful model to study of morphological aspects of dengue virus infection.