Interferon-β response is impaired by hepatitis B virus infection in Tupaia belangeri

Abstract

To date, the chimpanzee has been used as the natural infection model for hepatitis B virus (HBV). However, as this model is very costly and difficult to use because of ethical and animal welfare issues, we aimed to establish the tupaia (Tupaia belangeri) as a new model for HBV infection and characterized its intrahepatic innate immune response upon HBV infection. First, we compared the propagation of HBV genotypes A2 and C in vivo in tupaia hepatocytes. At 8-10days post infection (dpi), the level of HBV-A2 propagation in the tupaia liver was found to be higher than that of HBV-C. Abnormal architecture of liver cell cords and mitotic figures were also observed at 8 dpi with HBV-A2. Moreover, we found that HBV-A2 established chronic infection in some tupaias. We then aimed to characterize the intrahepatic innate immune response in this model. First, we infected six tupaias with HBV-A2 (strains JP1 and JP4). At 28 dpi, intrahepatic HBV-DNA and serum hepatitis B surface antigens (HBsAg) were detected in all tupaias. The levels of interferon (IFN)-β were found to be significantly suppressed in the three tupaias infected with HBV A2_JP4, while no significant change was observed in the three infected with HBV A2_JP1. Expression of toll-like receptor (TLR) 1 was suppressed, while that of TLR3 and TLR9 were induced, in HBV A2_JP1-infected tupaias. Expression of TLR8 was induced in all tupaias. Next, we infected nine tupaias with HBV-A2 (JP1, JP2, and JP4), and characterized the infected animals after 31 weeks. Serum HBsAg levels were detected at 31 weeks post-infection (wpi) and IFN-β was found to be significantly suppressed in all tupaias. TLR3 was not induced, except in tupaia #93 and #96. Suppression of TLR9 was observed in all tupaias, except tupaia #93. Also, we investigated the expression levels of cyclic GMP-AMP synthase, which was found to be induced in all tupaias at 28 dpi and in four tupaias at 31 wpi. Additionally, we evaluated the expression levels of sodium-taurocholate cotransporting polypeptide, which was found to be suppressed during chronic HBV infection. Thus, the tupaia infection model of HBV clearly indicated the suppression of IFN-β at 31 wpi, which might have contributed to the establishment of chronic HBV infection.

Pathogenesis and Immune Response Caused by Vector-Borne and Other Viral Infections in a Tupaia Model

“…In addition, we also observed modulation of cytokines/chemokines in DENV-infected Tupaia cells, suggesting the involvement of these innate immune components in DENV infection, similar to that observed in human infections [34][35][36]. A recent study [37] demonstrated that DENV could activate a cGAS response and in an in vitro study of DENV infection we detected the expression pattern of cGAS in the sample from a previous study [24], as described [16]. We observed that DENV serotype 1, but not other serotypes, significantly upregulated cGAS mRNA expression 72 h post-infection in Tupaia cells (Figure 1).…”

“…In addition, Ruan et al demonstrated the similarities of pathological changes in HBV-infected Tupaia liver tissues with the disease progression in humans [61]. In a recent study, we found that the establishment of chronic HBV infection and an impaired IFN-β response could be caused by the HBV-A2 genotype in the Tupaia infection model [16]. On the other hand, during acute infection, impaired IFN-β response was only observed in HBV-A2_JP4-infected Tupaia, but not in HBV-A2_JP1-infected Tupaia, which is suggestive for the role of IFN-β suppression towards the establishment of chronicity in the Tupaia model of HBV infection [16].…”

“…It was reported that the 3 untranslated region (UTR) of HCV can trigger a STING-dependent response in hepatocytes [57]. Using the liver samples from a previous study [19], we determined the intrahepatic expression pattern of cGAS during HCV chronic infection in Tupaia as described previously [16]. Significant upregulation of cGAS mRNA was observed in HCV1b-and HCV2a-infected Tupaia (#22 and #24, Figure 2) but not HCV1a (#21, Figure 2).…”

“…However, due to economic and ethical reasons, the use of chimpanzees for experimental infection is difficult. The Tupaia is the only non-primate animal that shows susceptibility to human HBV infection and several studies have demonstrated the utility of the Tupaia as an immunocompetent animal model for HBV infection [13,15,16]. In addition, Ruan et al demonstrated the similarities of pathological changes in HBV-infected Tupaia liver tissues with the disease progression in humans [61].…”

“…The high degree of genetic homology between several neuromodulator receptor proteins in tree shrews and primates enabled the expanded use of Tupaia in preclinical research, and thus, Tupaia have been used in a variety of research fields [11,12]. In infectious disease research, the Tupaia has appeared as a promising candidate animal model and has shown susceptibility to several important human viral pathogens, including Hepatitis B virus (HBV) [13][14][15][16], Hepatitis C virus (HCV) [17-19], Hepatitis E virus [20], Influenza virus [21-23], Dengue virus [24], Zika virus [25,26], Epstein-Barr virus [27], herpes simplex virus [28], Coxsackie virus A16 [29], Newcastle disease virus, and Sendai virus [30]. Construction of a complete Tupaia belangeri transcriptome database by whole-genome and comprehensive RNA sequencing may facilitate a better understanding of viral pathogenesis and host immune responses [10].…”