Hybridoma cell lines producing monoclonal antibodies to the JHM strain of mouse hepatitis virus-4 (MHV-4) were established. By indirect immunofluorescence and immune precipitation, monoclonal antibodies of three viral polypeptide specificities were characterized. Monoclonal antibodies to nucleocapsid reacted in the cytoplasm of infected cells and precipitated the 60,OOOd nucleocapsid polypeptide (VP-4) of MHV-4. Other monoclonal antibodies reacted both in the cytoplasm and on the surface of infected cells and were found to precipitate the 170,OOOd viral glycoprotein (GP-1). A third set of monoclonal antibodies reacted both in the cytoplasm and on the surface of infected cells and precipitated the 25,OOOd viral glycoprotein (GP-5) and its precursor VP-6 (23,OOOd). Anti-GP-1 alone had direct neutralizing activity for MHV-4 virus, while in the presence of complement both anti-GP-1 and anti-GP-5 neutralized virus. Only anti-GP-1 had the ability to inhibit the spread of infection due to fusion in L241 cells. Thus, the viral glycoprotein GP-1 likely contains both the attachment and fusion activities of MHV-4.

Experimental allergic encephalomyelitis (EAE) serves as a model for autoimmune diseases mediated by T lymphocytes. Following sensitization to rat, mouse or guinea pig myelin basic protein (MBP) in complete Freund's adjuvant, inbred mouse strains PL/J (H-2u), SJL/J (H-2s) and (PL/J X SJL/J)F1((PLSJ)F1) develop EAE. Whereas sensitization to the N-terminal 37 amino-acid peptide of rat or guinea pig MBP [MBP(1-37)] induces EAE in PL/J mice, immunization to the C-terminal peptide (89-169) leads to EAE in SJL/J mice. The immune response to MBP in (PLSJ)F1 mice is not co-dominant; sensitization to the N-terminal peptide induces EAE, while sensitization to the C-terminal peptide does not. We have generated MBP-specific T-cell clones restricted to class II (Ia) antigens of the major histocompatibility complex (MHC) from PL/J and (PLSJ)F1 mice following sensitization to rat MBP. Two such I-Au-restricted T-cell clones that proliferate in response to the encephalitogenic N-terminal MBP peptide and recognize a shared determinant with mouse (self) MBP cause paralysis in 100% of (PLSJ)F1 mice tested. Paralysis is induced even when recipients are injected with as few as 1 X 10(5) cloned T cells. Relapsing paralysis followed in two-thirds of the recipients after recovery from acute paralysis, whereas one-third developed chronic persistent paralysis, a form of EAE not usually seen. Histopathology revealed intense perivascular inflammation, demyelination and remyelination within the central nervous system of paralysed mice. The experimental disease induced with these clones shares important features with human demyelinating diseases such as multiple sclerosis. This is the first demonstration that T-cell clones that respond to a defined self-antigen can induce clinical and histological autoimmune disease.

Monoclonal hybridoma antibodies directed against the polypeptides of murine hepatitis virus-4 (JHM strain) were tested for their ability to alter the course of a normally lethal intracerebral virus challenge. Three monoclonal antibodies directed against two distinct epitopes on the E2 glycoprotein of MHV-4 protected mice against lethal virus challenge and converted the infection from fatal encephalomyelitis to demyelination. A single neutralizing antibody directed against a third epitope on E2 as well as seven nonneutralizing antibodies to E2, E1, and N polypeptides did not protect against challenge. In mice which received protective antibody, MHV-4 infection was not blocked, however, virus grew to lower titers in liver and brain, and virus replication in the CNS was more restricted than in unprotected mice. Decreased involvement of neurons in the brains of protected mice was observed, and no evidence of neuronal infection in the spinal cords was found. In contrast, oligodendrocytes were infected in the presence of protective antibody, and evidence of demylination associated with mononuclear cell infiltration was found. These studies demonstrate that antibody to a single epitope on a viral glycoprotein can substantially alter the course and phenotype of disease.