Contributions
Abstract: P426
Type: Poster Sessions
Abstract Category: Pathology and pathogenesis of MS - Experimental models
Mouse hepatitis virus (MHV) infection in mice causes meningoencephalitis and myelitis with subsequent axonal loss and demyelination which mimics certain pathological feature of human neurological disease multiple sclerosis. MHV induced neuroinflammation can follow “inside-out” mechanism, where pathology initiates within axons and leads to damage to its outer myelin covering. Previous study demonstrated spike protein (S) (host attachment protein) is one of the major genomic determinants of pathogenic properties and viral spread from brain to the spinal cord as well as from grey to white matter and causes white matter myelin loss and axonal degeneration. Fusion peptides (FP) in S are key players that mediate intercellular viral spread. A central proline residue of FP has been alluded to have a distinctive role in spread from one cell to another. The MHV S from strain RSA59 (PP) contains two central consecutive proline(s) in the FP. When one proline is deleted, RSA59 (P) produces significant differences in neural cell syncytia formation and viral titer post infection in vitro. NMR studies of 16-mer FP fragment from RSA59 (PP) shows a more ordered cis isomeric helix-turn-helix structure in methanol than its trans counterpart in water. Comparative molecular dynamics studies on the trimeric spike fusion domain and the FP reveal a dual role for the central proline, wherein in aqueous environment it imparts conformational rigidity to the fusion apparatus and facilitates the same by promoting a more ordered structure in the membranotropic environment through ready isomerization to a cis peptide form. RSA59 (PP) and RSA59 (P) infection studies with C57Bl/6 mice by transcranial inoculation produces distinct patterns of injury at day 3 post-infection. Both cause similar degrees of necrotizing hepatitis and meningitis, but only RSA59 (PP) produces widespread encephalitis that extends deeply into the brain parenchyma with extensive apoptosis of neurons and glia. In contrast, RSA59 (P) infection is limited with minimal extension of viral antigen from the meninges and the inoculating needle tract. By day 6 post-infection, both viruses are mostly cleared from the brain despite considerable residual microglial activation. Interestingly, RSA59 (P) produces significantly reduced demyelination at chronic stage of the disease compared to RSA59 (PP). Our work provides a premise for understanding the mechanism of virus induced demyelination and axonal loss.
Disclosure: The authors have no competing financial interests. The work is supported by Department of Biotechnology (DBT), New Delhi, India.
Abstract: P426
Type: Poster Sessions
Abstract Category: Pathology and pathogenesis of MS - Experimental models
Mouse hepatitis virus (MHV) infection in mice causes meningoencephalitis and myelitis with subsequent axonal loss and demyelination which mimics certain pathological feature of human neurological disease multiple sclerosis. MHV induced neuroinflammation can follow “inside-out” mechanism, where pathology initiates within axons and leads to damage to its outer myelin covering. Previous study demonstrated spike protein (S) (host attachment protein) is one of the major genomic determinants of pathogenic properties and viral spread from brain to the spinal cord as well as from grey to white matter and causes white matter myelin loss and axonal degeneration. Fusion peptides (FP) in S are key players that mediate intercellular viral spread. A central proline residue of FP has been alluded to have a distinctive role in spread from one cell to another. The MHV S from strain RSA59 (PP) contains two central consecutive proline(s) in the FP. When one proline is deleted, RSA59 (P) produces significant differences in neural cell syncytia formation and viral titer post infection in vitro. NMR studies of 16-mer FP fragment from RSA59 (PP) shows a more ordered cis isomeric helix-turn-helix structure in methanol than its trans counterpart in water. Comparative molecular dynamics studies on the trimeric spike fusion domain and the FP reveal a dual role for the central proline, wherein in aqueous environment it imparts conformational rigidity to the fusion apparatus and facilitates the same by promoting a more ordered structure in the membranotropic environment through ready isomerization to a cis peptide form. RSA59 (PP) and RSA59 (P) infection studies with C57Bl/6 mice by transcranial inoculation produces distinct patterns of injury at day 3 post-infection. Both cause similar degrees of necrotizing hepatitis and meningitis, but only RSA59 (PP) produces widespread encephalitis that extends deeply into the brain parenchyma with extensive apoptosis of neurons and glia. In contrast, RSA59 (P) infection is limited with minimal extension of viral antigen from the meninges and the inoculating needle tract. By day 6 post-infection, both viruses are mostly cleared from the brain despite considerable residual microglial activation. Interestingly, RSA59 (P) produces significantly reduced demyelination at chronic stage of the disease compared to RSA59 (PP). Our work provides a premise for understanding the mechanism of virus induced demyelination and axonal loss.
Disclosure: The authors have no competing financial interests. The work is supported by Department of Biotechnology (DBT), New Delhi, India.