Rubella virus: intracellular polypeptide synthesis

Altered membrane fatty acids of cultured human retinal pigment epithelium persistently infected with rubella virus may affect secondary cellular function

Persistent infection with rubella virus (RV) can alter secondary functions of host cells. Previously we had documented defective phagocytosis of latex beads by cultured human retinal pigment epithelial cells (RPE), persistently infected with M-33 RV (RPE/RV). Here, examining possible mechanisms for altered function, we reported significant differences between the total esterified fatty acids (FA) of RPE and RPE/RV membranes, measured by gas liquid chromatography. RPE/RV contained an increased proportion of saturated FA, particularly palmitic acid, with a presence of unusual chromatographic FA peaks co-eluting with odd-numbered long-chain carbon atom FA not normally found in human cells. Apical membrane microvilli, structures essential to phagocytic activity of RPE and RPE/RV, observed by scanning and transmission electron microscopy, were similar in number and appearance between uninfected RPE and RPE/RV cells before and after latex bead addition. However, RPE/RV microvilli, possibly reflecting altered membrane FA composition, engaged latex beads less effectively than uninfected RPE microvilli. In addition, microvilli remained abnormally distributed on RPE/RV cell surfaces at 48 h after latex addition. Thus, RV persistent infection may affect the cellular membrane fluidity and functional activity of human cells with increased saturated FA proportions and altered FA components of membrane phospholipids. These changes may participate in the defective phagocytosis of RPE/RV.

Interaction of rubella virus with human immune cells. I. Permissiveness of lymphocyte subpopulations

The ability of rubella virus to infect and replicate in various lymphocyte subpopulations was examined. Purified populations of B-cells, CD4+ T-cells and CD8+ T-cells were found to support high levels of viral replication. In addition, when mixed PBMC were infected in vitro, viral antigen was shown to be expressed on the surfaces of CD4+ and CD8+ T-cells by flow cytometry indicating that RV does not have a selective tropism for a specific type of lymphoreticular cell.

Selective inhibition of protein synthesis by hypertonic medium in Marituba (Bunyaviridae) virus-infected L-A9 cells

Elevation of the NaCl concentration in the growth medium of L-A9 cells caused an inhibition of the protein synthesis accompanied by a complete breakdown of polyribosomes. However, a complete recovery of the rate of protein synthesis was observed when isotonicity was restored. In Marituba virus infected cells, protein synthesis became resistant to hypertonic treatment. Under hypertonic conditions cellular protein synthesis was selectively suppressed and an enhancement of virus proteins was observed. Analysis of the virus specific proteins by polyacrylamide gel electrophoresis revealed that the synthesis of G1 was unalterable, and N was stimulated.

Persistent rubella virus infection associated with chronic arthritis in children

We isolated rubella virus from lymphoreticular cells in 7 of 19 children with chronic rheumatic disease, including patients with systemic-onset juvenile rheumatoid arthritis (Still's disease) (1 of 5), polyarticular juvenile rheumatoid arthritis (2 of 2), pauciarticular juvenile rheumatoid arthritis (2 of 6), and seronegative spondyloarthritis (2 of 6). In contrast, rubella virus was not isolated from the control group, which included eight normal subjects and eight patients with other connective tissue diseases or traumatic joint effusion. In most members of the study group, mononuclear cells from both synovial fluid and peripheral blood were examined. Rubella virus was isolated from both cell populations in three patients, from only peripheral blood in one, and from only synovial fluid in two. In the children with systemic-onset juvenile rheumatoid arthritis, only peripheral blood was examined, and of the five samples analyzed, one was shown to have rubella virus. Virus was isolated on more than one occasion from four of seven persons. Persistence of rubella virus in lymphoreticular cells in 35 per cent of these cases of juvenile arthritis supports the view that the virus may be an etiologic agent in chronic human joint disease, but further work will be required to support this suggestion.

The effect of dibutyryl cyclic AMP on restricted replication of rubella virus in rat glial cells in culture

Normal adult rat glial (RG) cells in culture have been shown to restrict rubella virus (RV) replication, permitting the synthesis of only five of the seven intracellular viral polypeptides associated with a normal, productive infection. Recently uninfected RG cells have been reported to differentiate into mature glia in the presence of dibutyryl cyclic AMP (dB-cAMP), suggesting that the RG cells may be a continuous cell line of undifferentiated glioblasts. This communication describes the effect of dB-cAMP on rubella-infected RG cells. Following exposure to dB-cAMP, RV antigens could be demonstrated in the cytoplasm of the differentiating glioblasts, all seven intracellular RV polypeptides could be detected following immune precipitation, slab gel electrophoresis, and autoradiography, and infectious progeny virions could be titered from the tissue culture medium. These data indicate that dB-cAMP promotes glioblast maturation and a concomitant activation of RV replication.

Identification of rubella virus structural proteins by immunoprecipitation

Immunoprecipitation of [3H]amino acid labelled virus with monoclonal or human convalescent rubella sera and subsequent analysis by electrophoresis and fluorography, revealed three structural proteins of rubella virus: VP3: 59,000; VP2: 44,800; and VP1: 33,000.

Rubella-associated arthritis: rescue of rubella virus from peripheral blood lymphocytes two years postvaccination

Rubella virus was isolated from the peripheral lymphocytes of a patient with rubella-associated arthritis 2 years after rubella vaccination. The rescue of the virus was carried out by stimulating the lymphocytes with mitogens for several days in cultures and then cocultivating them with RK13 cells at 35 degrees C. Rubella virus was detected by a variety of techniques, including electron microscopy, indirect immunofluorescence, polyacrylamide gel analysis of labeled viral proteins, and microfocus assay for infectious virus particles. Assessment of the immune status of the patient did not indicate any impairment of immune function associated with long-term persistence of the virus.