Biomedical subjects
Publications and source records attributed to S Katow.
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We have prepared four monoclonal antibodies to rubella virus E1 glycoprotein. Three nonoverlapping antigenic sites were delineated on E1 protein by competitive binding assays. Antibodies binding to one site were characterized by high hemagglutination inhibition (HI) titer but poor neutralizing activity. The addition of antiglobulin conferred neutralizing activity. Antibodies directed to two other antigenic sites had modest hemolysis inhibition but little or no HI and neutralizing activities. The addition of antiglobulin markedly augmented HI activity but had little effect on neutralizing activity. Epitopes defined by three antibodies were conserved among four rubella virus strains examined.
Serum samples from patients with various forms of rubella virus infection were tested for antibodies to each of three viral structural proteins by radioimmunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In most sera antibody to E1 protein was the predominant species. Sera from patients with congenital rubella syndrome, however, contained significantly more E2 antibody relative to E1 antibody than did sera from other rubella patients.
In titrating serum immunoglobulin G antibody to viruses by enzyme-linked immunosorbent assay, we used two rows of wells for serial twofold dilutions of the serum; in one row, a low concentration of a protein denaturant, 0.5 or 1.0 M guanidine hydrochloride, was added to the diluent so that the binding of low-avidity antibodies to viral antigens on the solid phase was inhibited. We then compared the antibody titration curves obtained in the two rows. We found that the addition of the reagent resulted in a parallel leftward shift of the curves and that the extent of the shift was greater in early than in late sera from all of the three infections studied (Japanese encephalitis virus, rotavirus, and rubella virus infections). This procedure may be useful for estimation of the avidity of antibody in serum and, with further evaluation, may prove to be applicable to single-serum diagnosis of virus infections.
The base composition of 32P-labelled RNA of rubella virus was shown to be; Gp:31.1, Ap:21.9, Cp:34.3 and Up:12.8 per 100 nucleotides. The result demonstrates that the virus is distinct from other members of family Togaviridae in that it possesses RNA with relatively high contents of Gp and Cp, and low content of Up. Viral RNA adsorbed to oligo (dT)-cellulose column was shown to be infectious, whereas no infectivity of RNA appearing in the void volume was found. This may indicate that viral RNA needs to carry a minimal length of poly(A) to be infectious.
Decrease in the susceptibility of embryonic chick neural retina cultures to the multiplication of various viruses was observed with increasing age of the embryo. In contrast the retinal cells supported the multiplication of Sindbis virus irrespective of the age when they were infected with the viral RNA. These results suggest that the restricted multiplication of the viruses observed is due to the modulated inability of the cell to process the adsorbed viruses for subsequent replication.
A strain of canine distemper virus was shown to be highly neuro-virulent in non-human primates. Intracerebral inoculation induced in monkeys histological lesions of encephalomyelitis, i.e., degenerative changes consisting mainly of neuronal damage and inflammatory changes such as perivascular cuffings and glial proliferation, in wide areas in the brain and spinal cord. In one monkey observed for 70 days, lesions with a tendency of subacute sclerosing were also noticed. Immunosuppression with cyclophosphamide or antithymocyte serum was found to aggravate the clinical course and to modify the histological lesions in the central nervous system as well as the level of antibody response to the virus in cerebrospinal fluid. Possible application of distemper encephalomyelitis in monkeys as a primate model for analysis of the immune mechanism involved in paramyxovirus-induced encephalomyelitis was discussed.
Neurovirulence of in vivo-passed wild measles virus and that of the cell-associated SSPE virus were compared by intracerebral inoculation into monkeys. The wild measles virus was found to lack neutrovirulence without producing neurological signs or significant histological changes in the brains, whereas the virus was confirmed to preserve the properties characteristic of the wild virus. In contrast, inoculation of the SSPE virus induced rapid onset of neurological signs with mild but definite histological changes including degeneration of nerve cells. The fact that SSPE virus exhibited neurovirulence in monkeys indicated importance of the current assay system for neurovirulence of measles vaccine by intracerebral inoculation into monkeys.
The Niigata-1 strain isolated from a patient with subacute sclerosing panencephalitis (SSPE) was inoculated intracerebrally into ferrets. Neurological signs developed in about 1 week in most of the animals. Histopathological examinations of the central nervous tissues revealed degenerative lesions in the parenchyma of the brains and inflammatory reactions predominantly in the meninges and choroid plexus. Virus antigen was demonstrated mainly in the nerve cells by immunofluorescent staining. The results indicated high affinity of the Niigata-1 strain to the nerve cells. In contrast, the Mantooth strain of SSPE virus in cell-free state did not exhibit neurovirulence in ferrets.
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