Antigenic modulation of measles subacute sclerosing panencephalitis virus in a persistently infected rat glioma cell line by monoclonal anti-haemagglutinin antibodies.

Rat glioma C6 cells persistently infected with measles subacute sclerosing panencephalitis (SSPE) virus (C6/SSPE) express the viral membrane proteins haemagglutinin (HA) and F on their cell surface as well as the intracellular proteins N, P and M. Previously we have shown that the addition of a polyclonal antibody against the HA antigen to the growth medium of C6/SSPE cells led to a gradual loss of all viral antigens. Here we show that the addition of a monoclonal antibody (MAb K83) leads only to a transient decrease in viral antigens during the first three passages. After the third passage viral antigens start to increase and after five passages they produce more antigens than at the premodulation level. At this point of the MAb treatment, MAb K83 no longer recognized the HA antigen on the surface of the cells and in virus particles produced by these cells in contrast with polyclonal antibodies or other MAbs against the HA antigen. The results suggest that specific variants of the SSPE virus with an altered HA antigen were selected by the MAb treatment.

Comparison of lytic and persistent measles virus matrix proteins by competition radioimmunoassay.

Measles virus matrix (M) proteins were compared by competitive monoclonal antibody-binding studies. Three strains of measles and of subacute sclerosing panencephalitis viruses were found to be identical in this way. The matrix protein formed by Edmonston strain virus during a persistent infection could be distinguished from that made in the lytic virus infection. It is concluded that structural alterations in the M peptide can occur during persistence.

Absence of M protein in a cell-associated subacute sclerosing panencephalitis virus.

Measles virus has been suggested to cause subacute sclerosing panencephalitis (SSPE), a slow central nervous system disease of children. However, several questions remain about the pathogenesis of SSPE. For example, it is not known whether alteration of the measles virus genome has a role in the initiation and persistence of the disease. Several studies have compared the RNA and protein composition of wild-type (wt) and SSPE strains of measles virus in a search for markers characteristic of the latter. All the studies used SSPE strains that had reverted to the budding, virion-producing form, similar to wt. We have shown, however, that only cell-associated non-budding strains of SSPE virus cause an SSPE-like persistent infection in young ferrets. Strong cell association and cell-fusing activity were essential for the virulence of measles virus in the brains of experimental animals and possibly humans. We have, therefore, compared the protein composition of virulent SSPE strains to that of the budding, non-virulent SSPE and wt strains. We report here that the M protein was not detectable in non-budding SSPE strains D.R., Biken and IP-3, and strain D.R. contained very little H protein.

The measles virus.

Measles is one of widely spread virus infections that is a major cause of deaths in some tropical areas. The measles virus is a member of the genus of Morbillivirus of the family of Paramyxoviridae. The virions contain six polypeptides, including one glycoprotein; two of them are surface proteins that possess hemagglutinating and hemolytic activities, one of them is polymerase. Replication of the measles virus is similar to that of other Paramyxoviruses. Besides the acute infection for measles virus a persistent infection is characteristic that affects central nervous system and inner organs. Molecular mechanisms of it were studied and the results are discussed to explain the pathogenesis of subacute sclerosing panencephalitis, systemic lupus erythematosus and other diseases in which measles or measles-like virus may be involved.

A comparison of polypeptides in measles and SSPE virus strains.

The polypeptide patterns of twelve subacute sclerosing panencephalitis (SSPE) and measles viruses have been compared by slab gel electrophoresis. The polypeptide patterns of nine strains of SSPE and measles virus were identical. Differences in the NP protein and the HA protein of the Oddo strain, the P protein of the large plaque variant of the Lec strain of SSPE and in the M protein of the Hu 2 measles strain could not be correlated with biological characteristics such as plaque morphology, origin or haemagglutination properties.