Association between nitric oxide synthesis and vaccination-acquired resistance to murine hepatitis virus by spf mice

Abstract

Murine hepatitis virus strain 3 (MHV-3) produces a strain-dependent pattern of disease, with A/J and BALB/c mice being considered models of resistance and susceptibility, respectively. A role for nitric oxide in controlling infection remains debatable; thus, we monitored nitric oxide levels in blood and liver of immunized and nonimmunized spf mice during infection by electron paramagnetic resonance. In parallel, liver histology, virus titers, and plasma alanine aminotransferase (ALT) activity were monitored. Nitric oxide synthesis was barely detectable in BALB/c mice, which showed a progressive increase in virus titers and ALT activity. These animals died with a shorter survival time than A/J mice. The latter displayed a less severe infection and presented detectable levels of nitric oxide as nitrosyl complexes in blood and liver at 72 hpi. Immunized mice from both strains became resistant to MHV-3 and showed comparable levels of nitrosyl complexes in blood and liver at an early time (24 hpi). Thereafter, nitric oxide levels decreased but remained detectable in blood up to 96 hpi. Immunized mice were capable of clearing the virus and clearance was inhibited by administration of a nitric oxide synthase inhibitor. Overall, the results support a role for nitric oxide in controlling MHV-3 infection.

Mouse Hepatitis Virus Infection Induces a Toll-Like Receptor 2-Dependent Activation of Inflammatory Functions in Liver Sinusoidal Endothelial Cells during Acute Hepatitis

“…We have demonstrated that MHV3, unlike attenuated variants, significantly altered NO release by LSECs. Susceptibility of mice to MHV3 infection has already been inversely correlated with NO levels in the liver, but the mechanism was not elucidated (50). The constitutive expression of NO by LSECs is essential for the regulation of intrahepatic sinusoidal blood flow and protects against liver diseases.…”

“…Liver suspension and cell culture supernatants were 10-fold serially diluted and tested for viral presence on L2 cells cultured in 96-well plates. Cytopathic effects (CPE), characterized by the occurrence of large syncytia and cell lysis, were recorded at 72 h p.i., and virus titers were determined according to the Reed-Muench method and expressed as log 10 TCID 50 .…”

“…Gene expression and production of IL-10, TGF-␤, IL-6, TNF-␣, CXCL1, CCL2, and CXCL10 in the livers of MHV3-, 51.6-MHV3-, and YAC-MHV3-infected mice. Groups of 5 or 6 C57BL/6 mice were intraperitoneally infected with 1,000 TCID50 of MHV3, 51.6-MHV3, and YAC-MHV3. At 24, 48, or 72 h p.i., livers were collected from mock-and virus-infected mice of each group.…”

Tempol ameliorates murine viral encephalomyelitis by preserving the blood–brain barrier, reducing viral load, and lessening inflammation

“…Strain A59 of coronavirus MHV (MHV-59A) was obtained from the Laboratoire de Virologie (Strasburg, France). The virus was propagated and plaque assayed on L929 cell cultures in modified Eagle's medium containing 10% fetal bovine serum at 37°C, as previously described [27].…”

“…Mouse brain and spinal cord tissues were collected, weighed, and homogenized in DMEM supplemented with 10% fetal bovine serum and 50 μg/ml gentamycin. The homogenates (10-100 mg/ml) were serially diluted and plaque assayed on L929 cells [27].…”