Comparative analysis of herpes simplex virus type 1 mutants that are defective in fusion function by using restriction endonuclease

Mutants derived from herpes simplex virus type 1 (HSV-1) strains, YH and KOS, that were defective in cell fusion function (r mutants) were examined for DNA structure using a restriction endonuclease and gel electrophoresis. A distinct difference in the restriction patterns was found in some r mutants. One which was derived from strain YH and belonged to complementation group A lost the BamHI cleavage site in the long inverted repeat regions. But the site could not be associated with the gene that was related to the cell fusion event, inasmuch as the other mutants belonging to the same complementation group had a normal BamHI site. The others, which belonged to complementation group G of strain KOS, had a deletion of approximately 2 kb (kilobase-pair) in the BamHI B fragment. A mixed infection was carried out with r410 and r426 which belonged to groups A and G of strain KOS, respectively, and the viruses of parental and recombinant types were isolated from the progeny. The BamHI restriction fragment patterns of the DNAs showed that all recombinants, which carried the cell fusion ability, had the normal BamHI fragment B. Thus, one of the genes associated with cell fusion function must be located in BamHI fragment B.

Laboratory diagnosis of viral myocarditis. A review

This review delineates the impact of molecular biology on the diagnosis and pathogenesis of coxsackie B viral myocarditis. The etiological role of the coxsackie B viruses in acute myocarditis is well established. A hallmark of most coxsackie B virus infections is extension cytopathology of the host cell. Recent evidence from studies of a nonlytic infection show that a coxsackie B virus can alter an infected cell which results from persistent infection. There are two other mechanisms for cardiac injury during coxsackie B virus infection. The first phase usually occurs during the first week after infection, and is probably a direct result of lytic infection to the myocytes and of the accompanying inflammatory response. The second phase of coxsackie B virus-induced myocarditis is accompanied by an autoimmune response to heart tissue, which occurs 2 weeks after infection. Genetic factors probably play a role, but their contribution has not yet been evaluated.

Possible role of H2O2-mediated complement activation and cytokines-mediated fibroblasts superoxide generation on skin inflammation

The degree of complement activation produced by hydrogen peroxide was estimated by the inhibition of serum homolytic activity (% IHA). Sera from patients with systemic lupus erythematosus and psoriasis vulgaris were resistant to hydrogen-peroxide-mediated complement activation. %IHA negatively correlated with ceruloplasmin level or catalase activity in systemic lupus erythematosus sera, but did not correlate with transferrin level. The addition of free metal ions, FeCl2 or CuCl2, promoted hydrogen-peroxide-mediated complement activation. These results suggest that hydroxyl radical is involved in complement activation and that the factors responsible for the insensitivity of pathological sera to H2O2 are catalase and ceruloplasmin in the sera. Human skin fibroblasts generate superoxide and tumor necrosis factor enhanced it, but interleukin-1 beta inhibited it. Normal serum cultured with fibroblasts for 24 h showed complement activation via catalase-inhibitable process, suggesting that hydrogen peroxide has an important role in fibroblast-mediated complement activation. It is speculated that fibroblasts and complement activation by oxygen radicals have an important role in inflammation and subsequent tissue damage at the site of skin lesion.

The effect of cimetidine on survival of mice infected with herpes simplex virus type 2, murine encephalomyelitis virus and vesicular stomatitis virus infections

The effect of cimetidine on survival was investigated in mice infected with herpes simplex virus type 2 (HSV-2), murine encephalomyelitis virus (GD-VII), and vesicular stomatitis virus (VSV). BALB/c mice, 5 weeks of age, were injected intraperitoneally (i.p.) with 5.5 x 10(5) plaque-forming units (PFU) of virus/0.5 ml, and cimetidine (1 mg/0.5 ml) was administered simultaneously. The survival rates of 80% and 85% in the cimetidine groups were significantly greater than the 10% and 23% for the control groups. The GD-VII- and VSV-infected control mice were dead at 3 days after virus inoculation. However, more cimetidine-treated mice survived than control mice. When anti-mouse T-cell serum or cyclosporine, which is a helper T-cell suppressor, was administered to BALB/c mice; the effect of cimetidine against the HSV-2 infection could be observed. When injected with anti-asialo GM1, BALB/c mice or beige mice with low natural killer (NK) cell activity were not affected by cimetidine. Lastly, cimetidine was shown to activate the cytotoxic action on NK cells. The above results indicate that the antiviral effects of cimetidine depend on NK cell activation.

Complement-activating properties of immune complexes are suppressed by IgM rheumatoid factor and enhanced by IgG rheumatoid factor

The effect of rheumatoid factor (RF) on complement-activating capacity of aggregated IgG was investigated. The degree of complement activation induced by the addition of specific amounts of aggregated IgG to patients' sera and normal sera was demonstrated by the inhibition of hemolytic activity (%IHA). The %IHA was significantly lower in rheumatoid arthritis (RA) sera and higher in systemic lupus erythematosus (SLE) sera, compared with normal sera. There was a negative correlation between %IHA and IgMRF/IgGRF ratio in RA and SLE sera, and RA synovial fluid. The %IHA and IgGRF were positively correlated in RA sera. The IgMRF/IgGRF ratio was significantly lower in SLE sera than in RA sera and systemic sclerosis sera, and was significantly lower in RA synovial fluid than in osteoarthritis synovial fluid. Isolated RF, consisting of mostly IgMRF class, inhibited complement-activating properties of aggregated IgG, depending on the concentration of RF. Isolated RF was further purified by the fractionation using high pressure liquid chromatography, and IgGRF and IgMRF were obtained. IgMRF significantly suppressed the complement-activating capacity of aggregated IgG, whereas IgGRF promoted it. These observations suggest that IgMRF acts protectively, while IgGRF induces inflammation. Thus, the expression of the biological activity of RF with special reference to immune complex interaction mainly depends on the IgMRF/IgGRF ratio.

Correlation between plaque size and genetic variation of type 3 poliovirus from a vaccinate

Vaccine strain derivatives could be serially isolated from the feces of a healthy infant for about 30 days after the second administration of a trivalent poliovirus vaccine. These were all identified as poliovirus type 3, and no other types were detected. The titer in feces increased gradually until day 19, when it reached a maximum, after which it decreased. The plaque size altered roughly in parallel with the changes in the titer. On day 11 it began to increase, becoming the highest abruptly on day 15, and then fell again. Oligonucleotide mapping analysis of RNAs of isolated viruses showed that the samples from days 1 and 11 exhibited the same patterns as those shown by the vaccine strain RNA. However, on day 15 many of the preexisting spots had decreased, and new ones appeared. On day 27, the pattern was again similar to that of the original virus, rather than that of the day-15 virus. A nonmetric distance scaling and cluster analysis suggested that all the strains were derived from the same origin and that the polioviruses on days 1, 11, 21, and 27 had closer relationships, but the poliovirus on day 15 was different.

Detection of low molecular weight IgM by immunoblot analysis in rheumatoid arthritis

The immunoblot technique was used to detect low molecular weight IgM (LMWIgM) in the serum and synovial fluid (SF) of patients with rheumatoid arthritis (RA). LMWIgM was detected in 64% of 58 RA sera and in 47% of 17 RA SF. The levels of IgM and rheumatoid factor (RF) were significantly higher in the positive sera of LMWIgM. Sequential studies revealed that LMWIgM appeared in the serum while the titer of RF was high. Our analysis also suggested the presence of several other oligomeric LMWIgM with monomeric IgM.

Studies on the classification of bovine enteroviruses

Bovine enteroviruses isolated from cattle and other ruminants in various areas of the world were classified into three distinct serotypes by cross-neutralization tests using criteria established for the differentiation of human enteroviruses. According to Western blot analysis, however, immunodominant structural polypeptides VP1 of the viruses tested have common epitopes, recognized by antisera to each of the three serotypes. These findings indicate that non-neutralizing epitopes on VP1 are generally conserved. It is, therefore, conjectured that bovine enteroviruses were derived from a common ancestor.

Generation of superoxide by immunologically stimulated normal human neutrophils and possible modulation by intracellular and extracellular SOD and rheumatoid factors

Rheumatoid synovial fluids generated significantly greater amounts of superoxide, lysosomal enzymes, and superoxide dismutase from neutrophils into extracellular fluid than osteoarthritic synovial fluids. Rheumatoid factors isolated from serum suppressed superoxide-generating activity of performed immune complexes, but did not suppress that of intermediate-sized immune complexes isolated from RA serum. Synovial fluid neutrophils has a greater capacity to generate superoxide and lower intracellular superoxide dismutase activity, compared with peripheral neutrophils of the corresponding patients. These results suggest that neutrophil superoxide release may be modulated, both by rheumatoid factor and by intracellular and extracellular superoxide dismutase.

Serum alkaline ribonuclease derived from vascular endothelial cells is raised in patients with rheumatoid vasculitis

We investigated the mechanisms of the marked increase of alkaline ribonuclease (RNase) in the sera of patients with rheumatoid arthritis associated with vasculitis. Among various tissues examined, blood vessels contained higher levels of alkaline RNase than acid RNase. Cultured human endothelial cells contained significantly higher amounts of alkaline RNase than acid RNase. In contrast, acid RNase was predominant in most other tissues and cells. Endothelial cells cultured with sera from patients with vasculitis released alkaline RNase into the extracellular medium. The phosphocellulose chromatographic profile of these sera differed from that of sera from healthy subjects. These results imply that the alkaline RNase in sera of patients with vasculitis is derived from blood vessels, probably from endothelial cells.

Superoxide generation by synovial fluid neutrophils enhanced by immune complexes and suppressed by rheumatoid factor in synovial fluid

Synovial fluid (SF) from patients with rheumatoid arthritis (RA) enhanced superoxide generation by neutrophils isolated from RA SF, in contrast to SF from patients with osteoarthritis. These superoxide generation-enhancing substances may be intermediate-sized immune complexes and a complement C5-derived fragment. Rheumatoid factor (RF) isolated from RA SF suppressed superoxide generation-enhancing activity of aggregated IgG. Therefore, biologically active RF may block the interaction of the immune complexes with neutrophils accumulating in RA SF, and protect the joint tissue from the effects of oxygen radicals or proteases.

Human vascular smooth muscle cells and endothelial cells lack catalase activity and are susceptible to hydrogen peroxide

51Cr release as lytic and cell detachment as nonlytic injury were employed to estimate neutrophil-mediated injury of cultured human vascular smooth muscle cells and endothelial cells. The reagents hydrogen peroxide or hypoxanthine-xanthine oxidase produced dose-dependent killing and nonlytic cell detachment, which were specifically inhibited by catalase but not by superoxide dismutase. The concentration of hydrogen peroxide or xanthine oxidase to induce cell detachment was less than lytic dose, suggesting that cell detachment was a much more sensitive assay of injury. Neutrophil-mediated cell lysis averaged 15% at most and was mostly dependent on hydrogen peroxide, while neutrophil-mediated cell detachment was nearly 100% and its dependency on hydrogen peroxide varied from 46% to 60%. These results suggest that vascular smooth muscle cells and endothelial cells in neutrophil-mediated events are destroyed by a hydrogen peroxide-dependent process, mainly via a nonlytic cell detachment mechanism. There was no striking difference of sensitivity to hydrogen peroxide between vascular smooth muscle cells and endothelial cells. Vascular smooth muscle cells and endothelial cells contained fairly high concentrations of superoxide dismutase, but not catalase, activity. The sensitivity of these cells to hydrogen peroxide but not to superoxide may arise from the fact that these cells lack intracellular catalase activity. The injury of vascular cells, which constitute important components of blood vessels, may lead to vascular injury and subsequent tissue damage.

Neutrophil-generated active oxygens in linear IgA bullous dermatosis

To examine the possible correlation between tissue injury and neutrophil-produced active oxygens (AOs) in patients with linear IgA bullous dermatosis (BD), we studied the capacity of neutrophils from six patients with BD to generate AOs. Cultured endothelial cells from human umbilical-cord vein were also incubated with the patients' neutrophils to assess AO-induced tissue injury. The AO production by patients' neutrophils was significantly elevated. The patients' neutrophils, as well as those from healthy controls preincubated with patients' serum, produced significantly increased levels of cytotoxic response on coincubation with chromium 51-labeled human endothelial cells. These results suggest that the tissue damage observed in BD may be partially due to both excessive production of AOs by neutrophils and a serum factor present in the patients, and further postulate the similar pathogenic process in dermatitis herpetiformis.

Human umbilical cord vein smooth muscle cells lack receptors for C3b and the Fc portion of immunoglobulin G

Under apparently normal conditions, the smooth muscle cells obtained from veins of human umbilical cord do not possess receptors for C3b or the Fc portion of IgG. These receptors were not expressed even after exposure to neutrophil lysate or a superoxide-generating system. The lack of these receptors argues against the possibility that smooth muscle cells participate in the pathogenesis of immune complex diseases through binding of C3b or Fc fragments.

Chemotactic activity generated in human serum from the fifth component of complement by hydrogen peroxide

Exposure of normal human serum to various concentrations of hydrogen peroxide as low as 68.8 microM resulted in the generation of chemotactic activity for human neutrophils, which was inhibited by adding catalase prior to the exposure. Maximum chemotactic activity was obtained by hydrogen peroxide at a concentration of 1.1 mM, and the concentration greater than 1.1 mM expressed decreased activity. On the contrary, hydrogen peroxide less than 1.1 mM produced dose-dependent chemotactic activity. The generation of chemotactic activity is initiated at an incubation time of 5 minutes, and subsequently increases with up to 90 minutes. The suppression of chemotactic activity was minimum even after 180 minutes. The maximum activity was obtained by 1024-fold dilution of serum treated with 13.8 mM hydrogen peroxide. These results suggest that the disappearance of chemotactic activity at the high-dose range of hydrogen peroxide is due to neutrophil deactivation rather than inactivation of the chemotactic activity after it was generated. Similarly, purified human C5 exposed to hydrogen peroxide generated chemotactic activity. The chemotactic activity was inhibitable by antiserum to human C5. The molecular weight of chemotactically active substance was approximately 15,000. The generation of chemotactic activity was not inhibited by addition of EGTA or EDTA. These results imply that hydrogen peroxide generates C5a-like chemotactic factor through hydrolysis of C5.

Role of stimulated neutrophils from patients with systemic lupus erythematosus in disturbed immunoreactivity, with special reference to increased oxygen intermediates generated by the neutrophils

Zymosan-stimulated neutrophils from 6 patients with untreated, active systemic lupus erythematosus (SLE), from patients with bacterial infections, and from healthy controls, were studied for production of oxygen intermediates (O-2, H2O2, OH . and chemiluminescence) and lysosomal enzymes. Oxygen intermediate production was highest in neutrophils from active SLE patients, while lysosomal enzyme release was highest in neutrophils from patients with bacterial infections. SLE neutrophils, upon culture with autologous or normal lymphocytes, markedly reduced the number of surviving OKT4+ cells and the proliferative response of the surviving cells to mitogens; a reduction was also observed amongst the surviving lymphocytes in the proportion of total T cells and OKT8+ cells, and in the generation of Con A induced suppressor activity. When superoxide dismutase and catalase were included in the neutrophil-lymphocyte co-cultures, the number of T- and OKT8+ cells, and the suppressor activity were restored but not completely (60-75%), the lymphocyte mitogenic response and number of OKT4+ cells were less well restored (40-50%). When lymphocytes were co-cultured with neutrophils from healthy or infected subjects, there was a mild decrease in mitogenic responses and OKT4+ cells, while the suppressor T-cell activity was markedly enhanced. These results were not affected by scavengers. These results suggest that in SLE, reduced T-lymphocyte subpopulations and altered immunoreactivity may be partially due to excessive production of oxygen intermediates and probably other factors by stimulated neutrophils; these results further suggest that in all the subjects, diseased or healthy, neutrophils generate unidentified factors other than oxygen intermediates that reduce the generation of OKT4+ cells and lymphocyte mitogenic responses, and that potentiate suppressor T-cell activity.

Variant strain of Propionibacterium acnes: a clue to the aetiology of Kawasaki disease

By means of anaerobic culture for 3-4 weeks a variant strain of Propionibacterium acnes was isolated from one lymph-node biopsy specimen, and from blood samples of five of twenty-three patients with early Kawasaki disease, but from only one of fifteen blood samples from patients after 8 days' illness. No anaerobe was isolated from sixty age-matched controls with various disorders, but the same bacillus with the same serotype was isolated from house-dust mites from six patients' homes. Patients had significantly higher serum agglutination titres to these strains than controls. The antigen moiety of P acnes was found in the patients' circulating immune complexes. Inoculation of animals caused various inflammatory lesions, particularly in the reticuloendothelial system, and coronary arteritis, myocarditis, and endocarditis in one of them, suggesting that the bacillus is pathogenic. The culture filtrate of this strain showed toxicity in tissue culture. This variant strain of P acnes may have a causative role in Kawasaki disease and house-dust mites a role as vectors.