Visualization of a neurotropic flavivirus infection in mouse reveals unique viscerotropism controlled by host type I interferon signaling

Abstract

Flavivirus includes a large group of human pathogens with medical importance. Especially, neurotropic flaviviruses capable of invading central and peripheral nervous system, e.g. Japanese encephalitis virus (JEV) and Zika virus (ZIKV), are highly pathogenic to human and constitute major global health problems. However, the dynamic dissemination and pathogenesis of neurotropic flavivirus infections remain largely unknown. Here, using JEV as a model, we rationally designed and constructed a recombinant reporter virus that stably expressed Renilla luciferase (Rluc). The resulting JEV reporter virus (named Rluc-JEV) and parental JEV exhibited similar replication and infection characteristics, and the magnitude of Rluc activity correlated well with progeny viral production in vitro and in vivo. By using in vivo bioluminescence imaging (BLI) technology, we dissected the replication and dissemination dynamics of JEV infection in mice upon different inoculation routes. Interestingly, besides replicating in mouse brain, Rluc-JEV predominantly invaded the abdominal organs in mice with typical viscerotropism. Further tests in mice deficient in type I interferon (IFN) receptors demonstrated robust and prolonged viral replication in the intestine, spleen, liver, kidney and other abdominal organs. Combined with histopathological and immunohistochemical results, the host type I IFN signaling was evidenced as the major barrier to the viscerotropism and pathogenicity of this neurotropic flavivirus. Additionally, the Rluc-JEV platform was readily adapted for efficacy assay of known antiviral compounds and a live JE vaccine. Collectively, our study revealed abdominal organs as important targets of JEV infection in mice and profiled the unique viscerotropism trait controlled by the host type I IFN signaling. This in vivo visualization technology described here provides a powerful tool for testing antiviral agents and vaccine candidates for flaviviral infection.

Establishment of pseudovirus infection mouse models for in vivo pharmacodynamics evaluation of filovirus entry inhibitors

“…11 , 12 , 13 , 14 , 15 . The bioluminescence imaging assay is a visualizing tool that has been used for viral studies in animal models 16 , 17 , 18 . Although some Ebola virus-like particles used for vaccine studies in vivo have been reported 19 , 20 , 21 , to the best of our knowledge, there is no study on the comparative in vivo pharmacodynamics of filovirus entry inhibitors on different genera of filoviruses.…”

A chimeric Japanese encephalitis vaccine protects against lethal yellow fever virus infection without inducing neutralizing antibodies

“…Host IFN signalling is the major barrier to the viscerotropism and for pathogenicity of neurotropic flaviviruses (58). In line, wild-type mice are poorly susceptible to infection with flaviviruses (28, 59–61) including YFV-17D infection/vaccination (34, 35, 62).…”

Novel Approach for Insertion of Heterologous Sequences into Full-Length ZIKV Genome Results in Superior Level of Gene Expression and Insert Stability

“…Although recombinant bioluminescent constructs created for several members of family Flaviviridae have been used to investigate viral replication dynamics and pathogenicity in animal models [15,16,39], previously described bioluminescent ZIKV systems have not been applied yet to studying virus tropism in live animals [17,18]. We demonstrated that among the four tested viruses expressing nLuc gene, the nLuc-50C/FrSh virus attained the highest titer in Vero cells, which was associated with the highest level of nLuc gene expression in the infected cells.…”

“…The genome contains 5 and 3 untranslated regions and encodes a single polyprotein, which is processed co-and post-translationally into three structural and seven non-structural proteins [12]. Because of the relatively small genome size and the monocistronic type of genome organization, the development of replication-competent recombinant flaviviruses stably expressing heterologous genes of interest in cell culture or in vivo has proved challenging [13][14][15][16]. Prior to this study, two approaches to generate replication-competent recombinant ZIKV expressing reporter genes had been described [17,18], both of which were based on the previously published strategy of capsid gene duplication [19]; however different ZIKV strains and different reporter genes were used, which would not allow us to perform a direct comparison of the level of heterologous gene expression and insert stability between these two approaches.…”