The gut-liver axis and the role of bacteria in severe dengue virus infection in mice
Patients with severe dengue virus (DENV) infection can experience hemorrhage, shock and organ damage that coincides with defervescence and declining viremia. In addition to vascular leak, published work has shown that gut barrier permeability and elevated serum lipopolysaccharide (LPS) levels correlate with DENV disease severity. We previously described profound gut pathology in a mouse model of infection. This led to the hypothesis that a loss of gut epithelial barrier integrity and the influx of microbial products contribute to exacerbated inflammation and severe dengue disease. Consistent with this, here we demonstrated that DENV2 infection of AG129 mice compromised the gut epithelial barrier, promoted bacterial translocation, and induced microbial changes indicative of dysbiosis, including a reduced abundance of putatively beneficial microbial taxa and disrupted microbial circadian oscillations. Depleting gut bacteria with antibiotics from 1-day post-infection sharply reduced gut pathology as well as viral RNA in the proximal colon and liver, and the number of infected Kupffer cells in the liver. There was no evidence for systemic suppression of viral replication. We propose that viral infection of intestinal macrophages leads to inflammatory damage and mucosal barrier breakdown, dysbiosis and gut leak, with gut bacteria-dependent products promoting the susceptibility of Kupffer cells to DENV infection. Given the importance of liver damage in severe and fatal dengue disease, therapies that protect the gut barrier may help reduce disease severity.