Roles of the three major phosphorylation sites of hepatitis B virus core protein in viral replication

Hepatitis B virus (HBV) core protein is a phosphoprotein. Its three major phosphorylation sites have been identified at the serine residues located at amino acids 157, 164, and 172. In order to investigate the role of core protein phosphorylation in HBV replication, these three serine residues were mutated to alanine to mimic nonphosphorylated serine or to glutamic acid to mimic phosphoserine. The nonphosphorylated core protein analog did not package the HBV pregenomic RNA, and the phosphorylated analog packaged the pregenomic RNA but failed to support viral DNA replication. These results indicate that the core protein phosphorylation may be important for pregenomic RNA packaging and that its dephosphorylation may be important for viral DNA replication. The individual roles of these three major phosphorylation sites in HBV replication were further investigated by being mutated to alanine in different combinations. The results showed that the serine residue at amino acid 157 was not essential for pregenomic RNA packaging, whereas the serine residues at amino acids 164 and 172 were more important. Furthermore, the serine residue at amino acid 157 was not essential for viral DNA replication or viral maturation.

Noncompetitive immunoassays using protein G affinity capillary chromatography and capillary electrophoresis with laser-induced fluorescence detection

A new and simple approach to perform immunoassay using protein G affinity capillary chromatography and laser-induced fluorescence detection was described. A noncompetitive assay for monoclonal anti-bovine serum albumin (BSA) was used to test the performance of the system. Fluorescein isothiocyanate labeled BSA was used as a tracer to determine anti-BSA in pM level. Capillaries with inner diameter of 150 microns were packed with recombinant protein G-bound perfusive support. The packed capillary was used to capture the immunocomplexes, which were subsequently desorbed by 100 mM glycine (pH 9.0). Open tube capillary electrophoresis-based immunoassay (CEIA) for anti-BSA was also performed. Using standard samples, calibration curves for anti-BSA was established in both assays. Compared with CEIA, this system improved the concentration sensitivity for about 100-fold due to the pre-concentration of immunocomplex in the protein G column, while the mass sensitivity was similar in the two methods.

Combined effects of probucol and benzafibrate on lipoprotein metabolism and liver cholesteryl ester transfer protein mRNA in cholesterol-fed rabbits

Probucol decreases and bezafibrate increases plasma high density lipoprotein-cholesterol (HDL-C) levels in humans. This study was performed to determine whether the HDL-C-lowering effects of probucol could be reversed by treatment with bezafibrate in hypercholesterolemic rabbits. Forty-nine normolipidemic Japanese White rabbits were divided into 5 groups [group 1: normal chow; group 2: 0.2% cholesterol (Ch) diet; group 3: 0.2% Ch and 1% probucol diet; group 4: 0.2% Ch and 1% bezafibrate diet; group 5: 0.2% Ch and 1% probucol plus 1% bezafibrate diet] and treated for 8 weeks. Plasma lipids, cholesteryl ester transfer protein (CETP) activity in the lipoprotein-deficient plasma fraction, CETP mRNA in liver tissue and plasma drug concentrations were investigated. Serum total cholesterol (TC) increased after the rabbits in groups 2, 3, 4 and 5 were fed Ch, but overall, no significant differences were observed in serum TC and triglyceride (TG) among these groups. Serum HDL-C levels increased (p<0.01) in the bezafibrate-treated group, but a significant (p<0.05) reduction in HDL-C was observed in both the Ch + probucol (group 3) and Ch + probucol plus bezafibrate (group 5) groups; no significant difference was observed between groups 3 and 5. Significant correlation (p<0.01) was found between serum low density lipoprotein cholesterol (LDL-C) levels and plasma probucol concentrations in groups 3 and 5, but no correlation was found between plasma concentrations of probucol/bezafibrate and serum HDL-C levels. CETP activity in the lipoprotein-deficient plasma fraction increased in the Ch-, Ch + probucol-, and Ch + probucol and bezafibrate-fed groups (groups 2, 3 and 5, respectively), whereas a significant reduction in this activity was observed in the Ch + bezafibrate-fed group (group 4). An analysis of covariance showed that the CETP activity responded more sensitively to drug treatment than did the serum HDL-C level. CETP mRNA in liver tissue was assessed by Northern blotting at 8 weeks, but no changes were observed among the 5 groups. Probucol decreased and bezafibrate increased serum HDL-C levels, through CETP activity without affecting liver CETP mRNA levels, and the decrease in HDL-C levels produced by probucol could not be reversed by bezafibrate.

Angiotensin I converting enzyme gene polymorphism and insulin resistance in patients with angina pectoris

The association between insertion/deletion polymorphism of the angiotensin I converting enzyme (ACE) gene and insulin resistance (IR) was investigated in 64 consecutive patients (F/M: 11/53) with angina pectoris without clinically manifest diabetes mellitus who underwent diagnostic coronary angiography. The observed frequency distribution of ACE genotypes did not deviate from that predicted from the Hardy-Weinberg equilibrium in this group. Patients with the ACE-ID genotype had significantly lower IR, as assessed by an oral glucose tolerance test (OGTT) and by homeostatic model assessment (HOMA), compared to those with the ACE-II genotype, as assessed by a multiple comparison analysis. Patients were divided into two groups with low and high HOMA-IR, and the I allele was seen more frequently in the high HOMA-IR group than in the low HOMA-IR group (0.62 v 0.47, respectively, by chi2 test, P < .05). Logistic regression analysis showed that the odds ratio for insulin resistance in patients with the II genotype, compared to those with the ID and DD-genotypes (assuming that the I allele has a recessive effect), was 4.0 (95% confidence interval, 1.2 to 16.5; P = .037), after adjusting for the presence of significant coronary atherosclerosis. In conclusion, the D allele was not associated with higher insulin resistance in patients with angina pectoris; that is, patients with the ID and DD genotypes were associated with a significantly lower risk of insulin resistance, compared to those with the II genotype.

In vivo kinetics of human apolipoprotein A-I variants in rabbits

BACKGROUND

Genetic variants of human apolipoprotein (apo) A-I, the major protein component of high-density lipoprotein (HDL), with a single amino acid substitution have been reported, and some of these result in very low plasma HDL-cholesterol (C) levels. Examining the kinetics of radiolabelled apolipoprotein is a straightforward technique for determining its metabolism in vivo. In this study, we investigated the in vivo kinetics of several human apo A-I variants, which we had identified previously, in rabbits.

MATERIALS AND METHODS

Apo A-I variants from heterozygous carriers of Lys-107-->0, Lys-107-->Met, Pro-3-->Arg, Pro-4-->Arg, Pro-165-->Arg and Glu-198-->Lys and the corresponding normal apo A-I were purified and then radioiodinated with 131I and 125I. A kinetic study of apo A-I variants was performed in normolipidaemic rabbits after simultaneous injection of the two isotopes that had been incorporated into HDL. The fractional catabolic rate (FCR) was calculated from the radioactive decay curve.

RESULTS

Acidic mature (negatively charged) apo A-I variants caused by a single amino acid substitution (Lys-107-->0, and Lys-107-->Met) were catabolized faster (FCR, 1.931 +/- 0.539 per day vs. 1.636 +/- 0.460 per day, P </= 0.01 using the Wilcoxon signed-rank test) and basic mature (positively charged) apo A-I variants (Pro-3-->Arg, Pro-4-->Arg, Pro-165-->Arg and Glu-198-->Lys) were catabolized more slowly (FCR 1.470 +/- 0.380 per day vs. 1.654 +/- 0.430 per day, P </= 0.01) than the corresponding normal mature apo A-I in vivo in rabbits. In addition, an inverse linear relationship was observed between the deviation in the FCR of variant human apo A-I from that of normal human apo A-I and the number of electric charges that the apo A-I variant carried (r = -0. 90, k = -0.188, P = 0.0003), as assessed by a linear regression analysis, suggesting that the electric charge of apo A-I variants may determine, at least in part, its in vivo kinetics in rabbits.

CONCLUSIONS

Genetic variants of apo A-I with a single amino acid substitution show abnormal kinetics, and the electric charge of a apo A-I variant could contribute to determining its kinetics in vivo in this xenologous model.

Molecular cloning and characterization of the rat ovarian 20 alpha-hydroxysteroid dehydrogenase gene

The rat 20 alpha-hydroxysteroid dehydrogenase (20 alpha-HSD) is an enzyme responsible for the catabolism of progesterone to the inactive 20 alpha-hydroxprogesterone. We have previously shown that the expression of this enzyme is not regulated by post-translational modification, but at the level of transcription. In this study we have established that the 20 alpha-HSD gene contains nine exons and have isolated a 2.5 kb promoter region. The transcription start site was identified and a TATA box was found. 5' deletions of this promoter significantly decreased basal promoter activity. Treatment with forskolin led to a dose dependent inhibition of the 2.5kg-20 alpha-HSD-luciferase construct. Computer analysis identified one CRE, two Nur77 response elements, two putative AP1 sites and one progesterone response element half-site. In summary, we have identified and partially characterized the promoter region of the rat ovarian 20 alpha-HSD and demonstrated that the regulatory elements for 20 alpha-HSD are present within a 2.5 kb 5' flanking region of the gene.

The expression of interleukin-6 in the pregnant rat corpus luteum and its regulation by progesterone and glucocorticoid

Interleukin (IL)-6, a multifunctional cytokine originally described as a T cell-derived factor, is also produced by different cell types, and it influences a wide variety of physiological and pathophysiological processes. Recent studies further suggest that IL-6 has a role in down-regulating hormone production by endocrine organs and can negatively affect the steroidogenic capacity of both ovaries and testes. Thus, the aims of this investigation were to examine whether IL-6 plays a role in luteolysis and, more specifically, to determine whether luteal cells express the IL-6 gene, whether this expression is developmentally and hormonally regulated in pregnancy, and whether the corpus luteum could be a target for IL-6 action. Using semiquantitative RT-PCR, messenger RNA (mRNA) encoding both components of the IL-6 receptor [the ligand-binding subunit (IL-6 R) and the IL-6 R-associated signal transducer (gp130)] were found to be highly expressed in corpora lutea throughout pregnancy. In contrast, IL-6 mRNA expression was barely detectable from day 4 through the end of pregnancy, whereas a sharp and abrupt expression of IL-6 mRNA occurred immediately after parturition. Although the corpus luteum does not express IL-6 mRNA during most of pregnancy, it could be induced to express this gene with an in vivo injection of the bacterial endotoxin, lipopolysaccharide. In addition, when corpora lutea from day-15 pregnant rats were isolated and maintained in culture, IL-6 mRNA that was undetectable at 0 h increased in a time-related manner and reached significant levels after 4 h of incubation, followed by a similar increase in IL-6 protein secreted in the culture media. Isolation of the small and large luteal cells by elutriation indicated that both cell populations can secrete IL-6 in culture. The apparent ability of luteal cells to spontaneously express IL-6 in vitro, together with the lack of IL-6 expression during most of pregnancy, led us to examine whether the IL-6 gene is silenced throughout pregnancy by luteotropic hormones. Corpora lutea from day-15 pregnant rats were cultured in the presence of different doses of progesterone; the synthetic glucocorticoid, dexamethasone; 17beta-estradiol; and PRL. Progesterone and dexamethasone markedly inhibited IL-6 mRNA expression, whereas 17beta-estradiol had a minimal inhibitory effect, and PRL did not affect IL-6 mRNA expression. In summary, results of this investigation have revealed that the rat corpus luteum expresses the IL-6 receptor system and that luteal cells are able to secrete IL-6. However, IL-6 gene expression is silenced during most of pregnancy, probably by the high levels of progesterone locally produced in the corpus luteum. The salient finding that progesterone and glucocorticoid strongly inhibit the expression of IL-6 in the corpus luteum suggests that one important luteotropic role of progesterone and glucocorticoids could be to prevent the expression of IL-6, which might have a deleterious effect on luteal function.

Mechanism of action of probucol on cholesteryl ester transfer protein (CETP) mRNA in a Chinese hamster ovary cell line that had been stably transfected with a human CETP gene

Probucol, a widely used lipid-lowering agent, is associated with a significant reduction of plasma high density lipoprotein (HDL)-cholesterol levels. To examine the mechanism of probucol HDL-lowering and probucol's effects on cholesteryl ester transfer protein (CETP) and cholesterol metabolism in cells, we used a Chinese hamster ovary (CHO) cell line that had been stably transfected with a human CETP gene (hCETP-CHO). After this cell line was incubated with various concentrations of probucol (5, 10 and 50 microM) for 24 h, mean intracellular probucol concentrations reached 0.47, 0.67, and 1.52 microg/mg cell protein, respectively. Northern blot analysis showed that cellular CETP mRNA was increased by probucol in a dose-dependent manner (137%, 162%, and 221% of the control, respectively). The specific CET activity in the culture medium, measured as the percentage of [3H]cholesterol oleate transferred from discoidal bilayer particles (which mimic HDL) to LDL, also increased in a dose-dependent manner. Intracellular total cholesterol levels were decreased to 87.5%, 74.9%, and 52.5% of the control, respectively. Probucol had no effects on HMG-CoA reductase activity or cholesterol synthesis from [14C]acetate in hCETP-CHO. However, 14C-incorporated cholesterol secretion into the culture medium from hCETP-CHO was increased to 181%, 256% and 354% of the control by 5, 10 and 50 microM probucol, respectively. We concluded that (1) treatment with probucol increased the CETP mRNA level and specific CET activity in the hCETP-CHO cell line, and (2) probucol promoted cholesterol efflux from hCETP-CHO, which resulted in a decrease in intracellular cholesterol levels.

Technetium-99m-labeled white blood cells: a new method to define the local and systemic role of leukocytes in acute experimental pancreatitis

OBJECTIVE

We developed a new method to quantitate leukocyte accumulation in tissues and used it to examine the time course and severity of acute experimental pancreatitis.

BACKGROUND

Leukocyte activation and infiltration are believed to be critical steps in the progression from mild to severe pancreatitis and responsible for many of its systemic complications.

METHODS

Pancreatitis of graded severity was induced in Sprague-Dawley rats with a combination of caerulein and controlled intraductal infusion. Technetium-99m (99mTc)-labeled leukocytes were quantified in pancreas, lung, liver, spleen, and kidney and compared with myeloperoxidase activity. The severity of pancreatitis was ascertained by wet/dry weight ratio, plasma amylase, and trypsinogen activation peptide in the pancreas. The time course of leukocyte accumulation was determined over 24 hours.

RESULTS

Pancreatic leukocyte infiltration correlated well with tissue myeloperoxidase concentrations. In mild pancreatitis, leukocytes accumulated only in the pancreas. Moderate and severe pancreatitis were characterized by much greater leukocyte infiltration in the pancreas than in mild disease (p < 0.01), and increased 99mTc radioactivity was detectable in the lung as early as 3 hours. 99mTc radioactivity correlated directly with the three levels of pancreatitis.

CONCLUSIONS

Mild pancreatitis is characterized by low-level leukocyte activation and accumulation in the pancreas without recruitment of other organs; marked leukocyte accumulation was found in the pancreas and in the lung in more severe grades of pancreatitis. These findings provide a basis for the pathophysiologic production of cytokines and oxygen free radicals, which potentiate organ injury in severe pancreatitis. This study validates a new tool to study local and systemic effects of leukocytes in pancreatitis as well as new therapeutic hypotheses.

Differential effects of nonselective nitric oxide synthase (NOS) and selective inducible NOS inhibition on hepatic necrosis, apoptosis, ICAM-1 expression, and neutrophil accumulation during endotoxemia

The roles of nitric oxide derived from either the constitutive endothelial NO synthase (eNOS or NOS3) or the inducible NOS (iNOS or NOS2) in hepatic injury during endotoxemia remain controversial. To investigate this further, rats received a bolus of lipopolysaccharide (LPS) following implantation of osmotic pumps containing one of two nonselective NOS inhibitors (NMA or NAME), one of two inducible NOS inhibitors (NIL or AG), or saline. The inhibitors were infused continuously into the liver via the portal vein. Treatment of LPS-injected rats with NMA and NAME resulted in 106 and 227% increases, respectively, in circulating hepatic enzyme levels compared to LPS-treated control rats. In contrast, infusion of the iNOS-selective inhibitors had no effect on the LPS-induced hepatic necrosis. In rats receiving NAME, LPS induced greater neutrophil infiltration and ICAM-1 expression than in the LPS + saline group, whereas NIL infusion did not. The increased hepatic necrosis and PMN infiltration in the LPS + NAME group was partially prevented by a simultaneous infusion of a liver-selective NO donor. Inhibition of PMN accumulation using an anti-ICAM-1 antibody or by PMN depletion using vinblastine pretreatment, however, did not reverse the increased necrosis with NAME infusion during endotoxemia. In contrast to the assessment for necrosis, increased apoptosis was observed in the livers of LPS-treated rats receiving infusions of either NAME or NIL, but not with LPS alone. These data indicate that NO produced by eNOS may be adequate to prevent necrosis by a mechanism independent of PMN, while induced NO appears to prevent apoptosis.

Calcium release and influx colocalize to the endoplasmic reticulum

Intracellular Ca2+ is released from intracellular stores in the endoplasmic reticulum (ER) in response to the second messenger inositol (1,4,5) trisphosphate (InsP3) [1,2]. Then, a poorly understood cellular mechanism, termed capacitative Ca2+ entry, is activated [3,4]; this permits Ca2+ to enter cells through Ca(2+)-selective Ca(2+)-release-activated ion channels [5,6] as well as through less selective store-operated channels [7]. The level of stored Ca2+ is sensed by Ca(2+)-permeant channels in the plasma membrane, but the identity of these channels, and the link between them and Ca2+ stores, remain unknown. It has been argued that either a diffusible second messenger (Ca2+ influx factor; CIF) [8] or a physical link [9,10] connects the ER Ca(2+)-release channel and store-operated channels; strong evidence for either mechanism is lacking, however [7,10]. Petersen and Berridge [11] showed that activation of the lysophosphatidic acid receptor in a restricted region of the oocyte membrane results in stimulation of Ca2+ influx only in that region, and concluded that a diffusible messenger was unlikely. To investigate the relationship between ER stores and Ca2+ influx, we used centrifugation to redistribute into specific layers the organelles inside intact Xenopus laevis oocytes, and used laser scanning confocal microscopy with the two-photon technique to 'uncage' InsP3 while recording intracellular Ca2+ concentration. Ca2+ release was localized to the stratified ER layer and Ca2+ entry to regions of the membrane directly adjacent to this layer. We conclude that Ca2+ depletion and entry colocalize to the ER and that the mechanism linking Ca2+ stores to Ca2+ entry is similarly locally constrained.

Excessive NO production dose not account for the inhibition of hepatic gluconeogenesis in endotoxemia

The pattern of inhibition of gluconeogenesis in hepatocytes was compared between endotoxemia in vivo and nitric oxide (NO) exposure in vitro. Fasted rats were injected with lipopolysaccharide (LPS; 12 mg/kg) or with vehicle alone. After 2-24 h, hepatocytes were isolated, placed in suspension, and incubated for 1 h with various gluconeogenic substrates that enter at different sites of the gluconeogenic pathway. Hepatocytes from LPS-treated rats exhibited up to a 50% decrease in gluconeogenesis for substrates that enter proximal to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) beginning at 6 h, followed by a nadir at 12 h after LPS. Although hepatocytes exposed to exogenous NO (S-nitroso-N-acetylpenicillamine) also exhibited a depressed gluconeogenesis, the pattern was not the same with inhibition in gluconeogenesis for substrates that enter the pathway both before and after GAPDH. Furthermore, when rats injected with LPS were subjected to a constant portal infusion (Alzet pump) of the NO synthase (NOS) inhibitors, NG-monomethyl-L-arginine or aminoguanidine, no changes in the LPS-induced gluconeogenesis suppression were seen. In addition, no difference in LPS-induced inhibition of gluconeogenesis was detected when hepatocytes from inducible NO synthase (NOS-2) knockout mice were compared with cells obtained from wild-type mice. Minimal decreases in GAPDH activity were measured in hepatocytes from the LPS-treated rats, whereas the activity of phosphoenol pyruvate carboxykinase (PEPCK) declined up to 40%, independent of NO synthesis. These data indicate that NO does not account for the inhibition of gluconeogenesis in endotoxemia, and they provide support for NO-independent reduction in PEPCK activity as a more plausible explanation.

Antisense technology reveals the alpha2A adrenoceptor to be the subtype mediating the hypnotic response to the highly selective agonist, dexmedetomidine, in the locus coeruleus of the rat

Alpha2 adrenergic agonists are used in the anesthetic management of the surgical patient for their sedative/hypnotic properties although the alpha2 adrenoceptor subtype responsible for these anesthetic effects is not known. Using a gene-targeting strategy, it is possible to specifically reduce the expression of the individual adrenoceptors expressed in the central nervous system and to thereby determine their role in hypnotic action. Stably transfected cell lines (PC 124D for rat alpha2A; NIH3T3 for rat alpha2C adrenoceptors) were exposed to 5 microM antisense oligodeoxynucleotides (ODNs) for alpha2A and alpha2C adrenergic receptor subtypes for 3 d. Individual receptor subtype expression, as determined by radiolabeled ligand binding, was selectively decreased only by the appropriate antisense ODNs and not by the "scrambled" ODNs. These antisense ODNs were then administered three times, on alternate days, into the locus coeruleus of chronically cannulated rats and their hypnotic response to dexmedetomidine (an alpha2 agonist) was determined. Only the alpha2A antisense ODNs significantly change the hypnotic response causing both an increase in latency to, and a decrease in duration of, the loss of righting reflex following dexmedetomidine; hypnotic response had normalized 8 d after stopping the ODNs. Therefore, the alpha2A adrenoceptor subtype is responsible for the hypnotic response to dexmedetomidine in the locus coeruleus of the rat.

Cell-specific expression of activin and its two binding proteins in the rat decidua: role of alpha 2-macroglobulin and follistatin

Rat decidual tissue is formed by two distinct decidual cell populations located either antimesometrially or mesometrially in the uterus. They differ in morphology, the genes they express, the proteins they secrete, and the role they play during pregnancy. Recently, we have shown that rat decidua expresses follistatin and alpha 2-macroglobulin (alpha 2-MG), two binding proteins to activin. In the present study, we determined whether the decidua of pregnant and pseudopregnant rats also expresses activin, whether activin messenger RNA (mRNA) is confined to a particular cell population, and whether it is regulated by its binding proteins. Decidual and placental tissues were collected at different stages of pseudopregnancy or pregnancy. mRNA expression was examined by in situ hybridization, reverse transcription-polymerase chain reaction, and Northern analysis. Developmental studies revealed that activin A became highly expressed in the antimesometrial decidua only from day 11 at a time when this tissue was undergoing extensive degeneration. Very little activin A mRNA could be detected in the mesometrial decidua. However, late in pregnancy, significant expression of activin A mRNA was detected in the mesometrial decidua undergoing extensive cell death at this stage. Developmental study revealed that activin A mRNA became expressed in the antimesometrial decidua only when follistatin mRNA disappeared from this tissue. Furthermore, mesometrial decidua expressing the most alpha 2-MG mRNA had reduced levels of activin A mRNA. These data suggest that follistatin and alpha 2-MG may, by binding to activin, prevent activin A from stimulating the expression of its own gene. To examine this possibility we first established that the rat decidua expresses activin receptor II at a constant level between days 11-15. Then we examined whether follistatin and alpha 2-MG down-regulate activin expression in a simian virus 40-transformed decidual cell line (GG-AD). These cells express activin A mRNA in abundance, very little follistatin, and no alpha 2-MG. Follistatin and alpha 2-MG caused a dose-related decrease in activin A mRNA levels in these cells. The same inhibitory effect was observed with activin A-blocking antibody. In summary, the results of this investigation demonstrate that rat decidual tissue expresses mRNAs for activin A and its two binding proteins; follistatin and alpha 2-MG. The expression of each mRNA is cell specific and developmentally regulated. The finding that both activin-binding proteins and antibody inhibit the expression of activin A in cultured decidual cells suggests that activin regulates its own gene expression in the decidua.(ABSTRACT TRUNCATED AT 400 WORDS)

[Confirmative test of human semen stain and mixed stain by immunohistochemical method using anti-human sperm monoclonal antibodies]

The stain of the human semen, the mixture of the human semen and vaginal secretion as well as the semen of the bull, goat, pig, dog, rabbit, rat and mouse was examined by the immunohistochemical method using anti-human sperm monoclonal antibodies (SMAB). The result revealed that the SMAB E10 could make a distinction between the human semen, the mixture of the human semen and vaginal secretion, and the seven kinds of animal semen. It is concluded that this method can be used for the species identification of the semen and the mixed stain under the general condition.

Effect of treatment on titer, function, and antigen recognition of serum antibodies to Actinobacillus actinomycetemcomitans in patients with rapidly progressive periodontitis

Although periodontal treatment by scaling and root planing (SCRP) is known to induce bacteremia, the effect of this procedure on the host immune response is not known. We have determined pre- and post-SCRP immunoglobulin G antibody titers to antigens of Actinobacillus actinomycetemcomitans in the sera of 22 patients with rapidly progressive periodontitis. We also assessed the ability of these sera to enhance phagocytosis and killing of A. actinomycetemcomitans by human polymorphonuclear leukocytes by using a polymorphonuclear leukocyte chemiluminescence (CL) assay. Specific anti-A. actinomycetemcomitans antibody titers were significantly increased at 6 and 12 months after beginning treatment, and CL values were significantly increased at 12 months, whereas mean interproximal pocket depths were significantly decreased at 12 months after beginning treatment. When patients were classified as either seropositive (twice the median titer of control subjects; n = 10) or seronegative (n = 12), both median titers and CL values were significantly increased for the seronegative group at 6 and 12 months after treatment. In the seropositive group, only the median titer was significantly increased at 12 months. Western blot (immunoblot) patterns for six seronegative and six seropositive patients differed remarkably at the baseline. Before treatment, all of the seropositive patients recognized high-molecular-mass lipopolysaccharide (LPS) and a large number of protein components. Patterns were virtually unaffected by therapy. Before treatment, only one of the seronegative patients recognized the LPS smear and none reacted strongly with protein components. Following treatment, slight LPS staining was observed for five of six seronegative patients and detection of protein bands was enhanced in all cases. We conclude that treatment by SCRP induces a humoral immune response, especially in seronegative patients, and that response may play a role in the observed beneficial effects of periodontal treatment.

Novel virulence properties of the Salmonella typhimurium virulence-associated plasmid: immune suppression and stimulation of splenomegaly

Mice infected subcutaneously with wild-type Salmonella typhimurium, SR11, developed a significant splenomegaly when compared with mice infected with an equal number of a plasmid-cured strain. Further, the bacterial load in the spleen at 14 days after infection, measured as colony-forming units per gram tissue, was significantly higher in mice infected with the parent strain than in mice infected with the plasmid-cured strain. These data confirm the previously reported plasmid-associated ability of Salmonella to multiply within the spleen. In addition, lymph node cells (LNC) from mice infected with the parent strain had a significantly reduced ability to proliferate in response to concanavalin A, a T-cell mitogen, and to heat-killed S. typhimurium cells when compared with LNC isolated from mice infected with the plasmid-cured strain. Finally, reintroduction of a functional Tn5-tagged 90-kb plasmid into a plasmid-free strain restored its capacity to cause a marked splenomegaly and to suppress lymph node cell proliferation in BALB/c mice. These data demonstrate that the 90-kb plasmid of highly virulent S. typhimurium strains mediates several novel pathogenic properties in infected mice: (1) enhancement of the ability of Salmonella to multiply within the spleen; (2) stimulation of a splenic inflammatory response as displayed by marked splenomegaly; and (3) a general suppression of lymphocyte responsiveness to both T-cell mitogens and specific Salmonella antigens.

Oral Salmonella typhimurium vaccine expressing circumsporozoite protein protects against malaria

Immunization with radiation-attenuated malaria sporozoites induces potent cellular immune responses, but the target antigens are unknown and have not previously been elicited by subunit vaccines prepared from the circumsporozoite (CS) protein. A method is described here for inducing protective cell-mediated immunity to sporozoites by immunization with attenuated Salmonella typhimurium transformed with the Plasmodium berghei CS gene. These transformants constitutively express CS antigens and, when used to immunize mice orally, colonize the liver, induce antigen-specific cell-mediated immunity, and protect mice against sporozoite challenge in the absence of antisporozoite antibodies. These data indicate that the CS protein contains T cell epitopes capable of inducing protective cell-mediated immunity, and emphasize the importance of proper antigen presentation in generating this response. Analogous, orally administered vaccines against human malaria might be feasible.