Impaired Virus Clearance, Compromised Immune Response and Increased Mortality in Type 2 Diabetic Mice Infected with West Nile Virus

Abstract

Clinicoepidemiological data suggest that type 2 diabetes is associated with increased risk of West Nile virus encephalitis (WNVE). However, no experimental studies have elucidated the role of diabetes in WNV neuropathogenesis. Herein, we employed the db/db mouse model to understand WNV immunopathogenesis in diabetics. Nine-week old C57BL/6 WT and db/db mice were inoculated with WNV and mortality, virus burden in the periphery and brain, and antiviral defense responses were analyzed. db/db mice were highly susceptible to WNV disease, exhibited increased tissue tropism and mortality than the wild-type mice, and were unable to clear the infection. Increased and sustained WNV replication was observed in the serum, peripheral tissues and brain of db/db mice, and heightened virus replication in the periphery was correlated with enhanced neuroinvasion and replication of WNV in the brain. WNV infection in db/db mice was associated with enhanced inflammatory response and compromised antiviral immune response characterized by delayed induction of IFN-α, and significantly reduced concentrations of WNV-specific IgM and IgG antibodies. The compromised immune response in db/db mice correlated with increased viremia. These data suggest that delayed immune response coupled with failure to clear the virus leads to increased mortality in db/db mice. In conclusion, this study provides unique mechanistic insight into the immunopathogenesis of WNVE observed in diabetics and can be used to develop therapeutics for the management of WNVE among diabetic patients.

Inflammasome Adaptor Protein Apoptosis-Associated Speck-Like Protein Containing CARD (ASC) Is Critical for the Immune Response and Survival in West Nile Virus Encephalitis

“…The levels of WNV-specific IgM antibodies were measured in the serum using microsphere immunoassay (MIA) for WNV envelope (E) protein (L2 Diagnostics), as described previously (34,35). Briefly, serum samples were incubated with magnetic microspheres (MagPlexTM-C) coated with a recombinant WNV E antigen for 30 min, followed by secondary goat anti-mouse IgG or Measurement of IFN-␣, cytokines, and chemokines.…”

“…Briefly, serum samples were incubated with magnetic microspheres (MagPlexTM-C) coated with a recombinant WNV E antigen for 30 min, followed by secondary goat anti-mouse IgG or Measurement of IFN-␣, cytokines, and chemokines. The levels of alpha interferon (IFN-␣) were measured in the sera using the VeriKine Mouse Interferon-Alpha ELISA (enzyme-linked immunosorbent assay) Kit (PBL Interferon Source), as described previously (34). The levels of cytokines and chemokines were measured in the sera and brain homogenates by Luminex assay using a Milliplex Map Mouse Cytokine/Chemokine kit (Millipore).…”

A Japanese Encephalitis Virus Genotype 5 Molecular Clone Is Highly Neuropathogenic in a Mouse Model: Impact of the Structural Protein Region on Virulence

“…Among the multiple factors governing JEV pathogenesis, viremia in blood and in peripheral organs was shown to be important for successful invasion of the CNS by JEV and by related flaviviruses (27,30,34). RNA was extracted from blood samples at 2, 3, and 4 days after peripheral inoculation of BALB/c mice.…”

“…5A and 7D). The viral load in blood is known to be an important factor in the development of JEV encephalitis, and the control of early viremia is crucial for disease development in the case of JEV (27,45) and related encephalitic viruses (30,34,46). It was also reported that a better infection of myeloid cells could be linked to an enhanced pathogenesis in a mouse model of JEV infection (47).…”

A Single Amino Acid Substitution in the M Protein Attenuates Japanese Encephalitis Virus in Mammalian Hosts

“…It is thus likely that this was also the case in vivo and that the mutant virus was recognized by the host immune system prior to its clearance from the bloodstream. Since early viremia in blood is known to be important for successful invasion of the central nervous system by JEV and by related flaviviruses (86)(87)(88)(89), the virus would have to mutate at this early stage of infection in order to develop pathogenesis. Importantly, we found that no viral RNA could be detected in the blood or in the organs (brain, liver, spleen, kidney) of mice inoculated with the mutant virus, thus suggesting that the virus was most likely cleared before reversion to a wild-type phenotype could occur in vivo (data not shown).…”