Murine Coronavirus Spike Protein Determines the Ability of the Virus To Replicate in the Liver and Cause Hepatitis

Abstract

Recombinant mouse hepatitis viruses (MHV) differing only in the spike gene, containing A59, MHV-4, and MHV-2 spike genes in the background of the A59 genome, were compared for their ability to replicate in the liver and induce hepatitis in weanling C57BL/6 mice infected with 500 PFU of each virus by intrahepatic injection. Penn98-1, expressing the MHV-2 spike gene, replicated to high titer in the liver, similar to MHV-2, and induced severe hepatitis with extensive hepatocellular necrosis. S A59 R13, expressing the A59 spike gene, replicated to a somewhat lower titer and induced moderate to severe hepatitis with zonal necrosis, similar to MHV-A59. S 4 R21, expressing the MHV-4 spike gene, replicated to a minimal extent and induced few if any pathological changes, similar to MHV-4. Thus, the extent of replication and the degree of hepatitis in the liver induced by these recombinant viruses were determined largely by the spike protein.Various strains of mouse hepatitis virus (MHV) induce different patterns of pathogenesis, including enteritis, hepatitis, encephalitis, and demyelination in the mouse (20,21). We are considering three strains here, MHV-A59, MHV-2, and MHV-4 (an isolate of MHV-JHM). The MHV-A59 strain is dualtropic, producing moderate to severe hepatitis as well as mild to moderate acute meningoencephalitis and chronic demyelination in C57BL/6 weanling mice (29, 30). The MHV-4 strain causes severe acute encephalitis, chronic demyelination, and only minimal levels of hepatitis (6, 23). The MHV-2 strain causes severe hepatitis and meningitis but is unable to cause encephalitis (7,20,42). There are previous studies demonstrating a relationship between attenuation of neurovirulence (6, 10, 13, 42) or hepatitis (14, 28) and the presence of mutations and variations in the spike (S) gene. The S protein, found on the virion envelope and on the plasma membrane of infected cells, is responsible for attachment to viral receptor and viruscell fusion during viral entry and for cell-to-cell fusion later during infection. S is a 180-kDa glycoprotein, which (in the case of most MHV spike proteins) is cleaved into two noncovalently associated 90-kDa subunits, the amino-terminal S1 and carboxy-terminal S2 subunits (14,33). It is speculated that the S1 subunit forms the globular head of the spike and the S2 subunit forms the membrane-bound stalk (8). Recently, a receptor-binding activity has been demonstrated using a recombinant protein containing the amino-terminal 330 residues of the S1 subunit of MHV-JHM (25, 41). S2 is believed to contain the domain that mediates fusion of viral and cell membranes (5, 8). The MHV-2 spike, while highly homologous in sequence to the spike proteins of other MHV strains, remains uncleaved and does not mediate fusion (44,45).Using targeted recombination technology (11,12,35), we have directly demonstrated that the spike protein is a major determinant of the neuropathogenic properties of MHV (39). When the S gene of MHV-4 was introduced into the background of MHV-A59, the resulting recombi...

Impaired immune responses following spinal cord injury lead to reduced ability to control viral infection

“…Infection of un-injured C57BL/6 female mice with 5 × 10 5 PFU MHV leads to acute hepatitis infection, but all mice survive and recover and this is associated with clearance of virus from the liver to below levels detectable by plaque assay (~200PFU/g tissue) (Eriksson et al, 2008; Navas et al, 2001). In contrast, all mice that received 5 × 10 5 PFU of MHV 1 week following a complete bilateral crush SCI at thoracic level-T3 died by 6 days post-infection (p.i.)…”

“…MHV-A59 replicates within the liver, without central nervous system infection, following intraperitoneal (i.p.) injection of C57BL/6 mice (Navas et al, 2001). Age-matched 5- to 7-week-old female C57BL/6 mice (H-2 b background) were purchased from the National Cancer Institute, Bethesda, Maryland, and used for all experiments.…”

Expression of CXC Chemokine Ligand 10 from the Mouse Hepatitis Virus Genome Results in Protection from Viral-Induced Neurological and Liver Disease

“…demonstrated that MHV-infected mice contained numerous lesions characteristic of MHV-induced hepatitis, consisting of large confluent areas of hepatocyte necrosis with a dense, mixed acute and chronic inflammatory infiltrate, primarily involving portal tracts (Fig. 6, E and F, arrows) (43,44). Numerous portal venules showed severe endothelialitis with infiltrating lymphocytes.…”

Coronavirus avian infectious bronchitis virus

“…Differences in the S protein, sometimes as few as one or two amino acids, of porcine transmissible gastroenteritis (TGEV) determine whether the virus is enteropathogenic or essentially nonpathogenic in pigs [3,59]. Genetically manipulated MHVs, with different tropisms with regard to disease in the liver and nerve tissue, have tropisms reflective of the strain from the S gene was derived [75,76]. We have shown that the S protein is an important factor with regard to the host cell range of IBV, at least in vitro.…”