Intracerebral infection with dengue-3 virus induces meningoencephalitis and behavioral changes that precede lethality in mice

Background: Dengue, one of the most important arboviral diseases of humans, may cause severe systemic disease. Although dengue virus (DENV) has been considered to be a non-neurotropic virus, dengue infection has been associated recently with a series of neurological syndromes, including encephalitis. In this work, we evaluated behavioral changes and inflammatory parameters in C57BL/6 mice infected with non-adapted dengue virus 3 (DENV-3) genotype I.Methods: C57BL/6 mice received 4 × 10³ PFU of DENV-3 by an intracranial route. We evaluated the trafficking of leukocytes in brain microvasculature using intravital microscopy, and evaluated chemokine and cytokine profiling by an ELISA test at 3 and 6 days post infection (p.i.). Furthermore, we determined myeloperoxidase activity and immune cell populations, and also performed histopathological analysis and immunostaining for the virus in brain tissue.Results: All animals developed signs of encephalitis and died by day 8 p.i. Motor behavior and muscle tone and strength parameters declined at day 7 p.i. We observed increased leukocyte rolling and adhesion in brain microvasculature of infected mice at days 3 and 6 p.i. The infection was followed by significant increases in IFN-γ, TNF-α, CCL2, CCL5, CXCL1, and CXCL2. Histological analysis showed evidence of meningoencephalitis and reactive gliosis. Increased numbers of neutrophils, CD4⁺ and CD8⁺ T cells were detected in brain of infected animals, notably at day 6 p.i. Cells immunoreactive for anti-NS-3 were visualized throughout the brain.Conclusion: Intracerebral infection with non-adapted DENV-3 induces encephalitis and behavioral changes that precede lethality in mice.