Novel Model of Multiple Sclerosis Induced by EBV-like Virus Generates a Unique B Cell Population

Objective: Multiple sclerosis (MS) is a chronic, autoimmune disease of the central nervous system. Prior infection with Epstein-Barr virus (EBV), a gammaherpesvirus, is deemed a necessary yet insufficient factor in the development of MS. The objective of this study was to determine whether the EBV-like virus, murid gammaherpesvirus 68, is sufficient to induce inflammatory demyelinating disease in a transgenic TCR mouse strain susceptible to CNS autoimmunity. Methods: B10.PL mice that express the myelin basic protein-specific transgenic T cell receptor (TCRMBP) were intranasally inoculated with murid gammaherpesvirus 68 virus (MHV68), PR8 influenza virus, or PBS. Mice were evaluated for the development of neurologic deficits. Flow cytometry and fluorescent microscopy were used to validate the infiltration of immune cells in the brain and spinal cord of TCRMBP mice. Single cell RNA sequencing of splenic B cells was performed to determine transcriptional changes that resulted from MHV68 infection. Results: MHV68-infected mice developed neurological deficits at a significantly higher frequency (70.8%) than the influenza (7.7%) or mock-infected mice (13.3%). MHV68 infected mice exhibited signs including optic neuritis and ataxia, which are infrequently observed in EAE mice, but common in MS patients. MHV68-infected mice exhibited increased focal immune cell infiltration. Single cell RNA sequencing identified the emergence of a novel, MHV68 infection-associated population of memory-like B cells that highly express genes associated with antigen presentation and costimulation. Conclusion: Infecting myelin basic protein specific TCR transgenic mice with the EBV analogue, MHV68, generates encephalitogenic disease without myelin immunization. MHV68 drives a distinct transcriptional program in B cells capable of enhanced antigen presentation and costimulation to drive an autoreactive T cell response. Overall design: Splenic B cells from four mice were isolated from wild-type B10.PL mice using negative magnetic bead isolation and subjected to 10X scRNA-seq platform. The first mouse was administered with PBS as a mock infection control. The second mouse was infected with PR8 influzena as an infection control. The final two mice were biological replicates of each other and they were both infected with the gammaherpesvirus MHV68. Splenocytes were collected on day 12 post infection for single-cell RNA sequencing.