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At least 703 records · Page 39Linked to original sources
PubMed1999

DNA immunization confers systemic, but not mucosal, protection against enteroinvasive bacteria.

Naked plasmid DNA (pRc/Y-hsp60) with a cytomegalovirus promoter and a sequence encoding Yersinia enterocolitica 60-kDa heat shock protein (Y-HSP60) was used for vaccination. After intramuscular injection of pRc/Y-hsp60, Y-hsp60 mRNA could be detected by reverse transcription-PCR in muscle, liver and spleen. A single immunization with pRc/Y-hsp60 induced significant Y-HSP60-specific T cell responses after 1 week. IFN-gamma production by spleen cells upon stimulation with Y-HSP60 was strictly dependent on the presence of CD4+ T cells, indicating the generation of a Th1 response upon DNA immunization. DNA immunization in addition induced strong Y-HSP60-specific IgG2a, weak IgG1, but not IgA antibodies. Immunization of BALB/c and C57BL/6 mice with pRc/Y-hsp60 conferred protection against disseminated Y. enterocolitica infection in spleen, but not at the site of mucosal entry, the Peyer's patches. Furthermore, pRc/Y-hsp60 vaccination did not induce cross-protection against related pathogens. Vaccination of beta2-microglobulin- and H2-I-Abeta-deficient mice was not protective, suggesting that both CD4+ and CD8+ T cells are required for protective immunity induced by DNA vaccination.

Animals↗
PubMed2001

LEDGF binds to heat shock and stress-related element to activate the expression of stress-related genes.

We have investigated the mechanism by which LEDGF protects cells against environmental stress. Our earlier report showed that a low level of LEDGF was present in the nucleus of most cell types and significant elevation of LEDGF level was induced by heat and oxidative stress. The cells overexpressing LEDGF-activated expression of heat shock proteins and enhanced survival of many cell types. Here we show that LEDGF binds to heat shock element (HSE) and stress-related regulatory element (STRE) to activate the expression of stress-related genes (Hsp27 and alphaB-crystallin). Apparently, HSE and STRE are present in promoters of many stress-related genes. Elevation of many stress-related proteins (STRPs) induced by LEDGF may protect cells against environmental stress. In yeast, it has been demonstrated that a single stress can activate the expression of multiple STRPs. This is known as "cross-protection," and now similar mechanism has been found in mammalian cells and LEDGF plays a vital role in it.

Base Sequence↗
PubMed1992

Echinococcus granulosus: use of an intermediate host mouse model to evaluate sources of protective antigens and a role for antibody in the immune response.

A Balb/cJ mouse model was used to determine which stage of the E. granulosus life cycle possessed the most potent protective antigens. Mice were immunized with crude extracts of protoscoleces, brood capsules, cyst fluid, adult worm tissue, eggs or oncospheres and then challenged intraperitoneally with 600 activated oncospheres. Sonically disrupted oncospheres induced the highest levels of protection (greater than 90%) at doses greater than or equal to 10(3) oncosphere equivalents per mouse. High levels of protection were maintained when these preparations were solubilized in SDS. Immunization with Taenia ovis or T. hydatigena oncosphere preparations induced a maximum of 62 and 40% cross-protection, respectively. In passive transfer experiments, serum from triple-infected immune donors that were completely resistant to subsequent challenge induced 69% protection in naive recipients (P less than 0.01). Serum from mice that had been immunized with oncosphere sonicates that were shown to be highly immune, failed to induce statistically significant protection in recipients. A sheep trial confirmed the protective ability of prior infections. Immunization of sheep with a SDS solubilized oncosphere preparation produced 91% protection (P less than 0.01).

Animals↗
PubMed2006

Toxoplasma gondii: cross-immunity against the enteric cycle.

Eight of nine cats inoculated with strain ME-49 and challenged with three different strains of Toxoplasma were immune to oocyst shedding, as ascertained with bioassays of their feces. In a second experiment, only toxoplasma asexual stages were seen in H&E stained gut sections of cats treated with suppressive doses of sulfamerazine and pyrimethamine starting 2 days after oral inoculation with cysts of the strain ME-49 and killed 6 days later. In a third experiment, four cats were similarly inoculated and treated for 20 days. Six weeks later, the cats received an oral homologous challenge with cysts, and none shed toxoplasma oocysts. An acceptable level of cross-protection was achieved with strain ME-49, and therefore, it can be used as a candidate strain from which antigens could be tested for enteric protection.

Animals↗
PubMed1974

Serological relationships among feline caliciviruses.

A total of 46 strains of feline calicivirus isolates from the United Kingdom, United States, Australia, and New Zealand were used in an investigation of their serological relationships based on the serum neutralization test. Although demonstrable antigenic variation exists between these isolates, it is shown that significant in vitro cross-activity exists between all these isolates to greater or lesser extent. All isolates tested may be regarded as serological variants of a single serotype of feline calicivirus. It is postulated that this relationship would provide for considerable cross-protection during successive exposures of cats to various feline caliciviruses.

Adsorption↗
PubMed1987

Characterization of tumor rejection antigen molecules of chemically induced murine colon tumor C-C26.

The molecular nature of a tumor-specific transplantation antigen (TSTA) of a chemically induced BALB/c mouse colon tumor C-C26 was investigated. The antigen was noncytolytically extracted by 2.5% n-butanol treatment of the cells. Crude butanol extract from C-C26, but not from colon tumor C-C51 and fibrosarcoma Meth-A of BALB/c mice could provide protection against the challenged C-C26 tumor in the transplantation experiment. Crude butanol extract from another syngeneic colon tumor C-C36 also induced a cross-protection against the challenged C-C26 tumor. C-C26 crude butanol extract was characterized by biochemical procedures including the Sephadex G200 column, lens culinaris affinity column, and anion-exchange Mono Q fast protein liquid chromatography column, and by the enzyme digestion study of the antigens and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The data indicated that C-C26 TSTA was eluted into fractions containing molecules of approximately Mr 200,000 on Sephadex G200 column chromatography. This antigen was also found in unbound fractions on a lens culinaris affinity column. The antigen was further separated into the fraction that was eluted with 0.4 M NaCl in an ionic strength on Mono Q fast protein liquid chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of this fraction showed the molecule with a molecular weight of 30,000. The enzyme digestion study indicated that the immunogenicity of the antigen was inactivated by papain but probably not by neuraminidase treatment. These data suggest that the immunogenic moiety of C-C26 TSTA molecules is located in the peptide portions rather than in sialic acid residues or carbohydrate portions. Furthermore, there are several similarities of the molecular characteristics between C-C26 TSTA and previously reported C-C36 TSTA, such as the amenability to n-butanol extraction. Lens culinaris lectin inaffinity, and ionic strength.

Animals↗
PubMed1995

Immunotherapy in gram-negative bacterial infections.

Endotoxins are responsible for initiation of septic shock which increases the number of fatalities in Gram-negative bacteremia among hospital patients. The mortality from septic shock is still high despite recent developments in antibiotic therapy because antibiotics are unable to decrease the level of free lipopolysaccharide in the blood stream. Another approach to the treatment and prevention of septicaemia involves stimulation of an immune response against LPS. It was found that immunization with the core structures of endotoxin conjugated with proteins protected animals against infections and endotoxic shock. Anticonjugate sera are of great interest because they are directed against conserved parts of LPS and therefore could have cross-reactive and cross-protective properties with respect to many Gram-negative rods.

Animals↗
PubMed1995

[Protective properties of antibodies raised against conjugates of endotoxin core oligosaccharides with proteins].

Endotoxins are responsible for initiation of septic shock which increases the number of fatalities in Gram-negative bacteremia among hospital patients. The mortality from septic shock is still high despite recent developments in antibiotic therapy. These substances are unable to decrease the level of free lipopolysaccharides in the bloodstream. Another approach to the treatment and prevention of septicaemia involves stimulation of an immune response against LPS. It was found that immunization with core structures of endotoxin conjugated with proteins protected animals against infections and endotoxic shock. Anticonjugate sera are of great interest because they are directed against common parts of LPS and therefore could have cross-reactive and cross-protective potencies towards many Gram-negative rods.

Animals↗
PubMed1980

Cross antigenicities of Leptospira interrogans serovar copenhageni Shibaura strain for preparing biological products in Japan.

Cross protective antigenicities of Leptospira were studied with 16 antisera to 13 serovars of Leptospira interrogans and a virulent strains "Shibaura (V)", which is now considered to belong to serovar copenhageni, for challenge. The antisera of the rabbits highly immunized with various serovar live antigens were examined for leptospiricidal activity; cross immunity was recognized only in the same serogroup, Icterohaemorrhagiae. Serovar icterohaemorrhagiae lacks a prt of the antigenic components of copenhageni, but the antiserum to the former showed potent leptospiricidal activity to Shibaura (V). Anti-copenhageni immune serum absorbed with the icterohaemorrhagiae antigen did not show any protective activity to Shibaura (V).

Agglutination Tests↗
PubMed1975

Experimental biology and pathogenesis of Junin virus infection in animals and man.

A fatal disease resembling Argentine haemorrhagic fever of man has been produced in guinea-pigs and mice by inoculation with Junin virus. Infected guinea-pigs show macroscopic and microscopic haemorrhagic lesions, marked bone marrow changes, decreased leukocytes and platelets in the peripheral blood, and impairment of immunological response. This response permits differentiation between pathogenic (XJ) and attenuated (XJ Cl(3)) strains. Guinea-pigs inoculated with the XJ Cl(3) strain develop an inapparent infection accompanied by slight haematological changes, the appearance of antibody, and protection against challenge with the pathogenic strain. The attenuated strain has been used successfully as an immunizing antigen in 636 human volunteers. Guinea-pigs infected with Tacaribe virus show cross-protection against Junin virus, with the presence of heterologous neutralizing antibodies. Suckling mice infected with Junin virus develop a typical viral encephalitis; the pathogenicity of the virus decreases with increasing age of the mice. Experiments with thymectomized mice and with mice treated with antithymocyte serum suggest that the pathogenicity of Junin virus in this host is related to the integrity of the thymus-dependent immune system. There is evidence that humoral antibodies do not play any role in the development of the encephalitic lesions but rather protect mice against Junin virus infection. A recent serological survey among laboratory workers and inhabitants of the endemic area has demonstrated the presence of inapparent infection with Junin virus.

Animals↗
PubMed2005

The immunogenicity of a conformationally restricted peptide mimetic of meningococcal lipooligosaccharide.

Life-threatening meningitis and septicaemia caused by Neisseria meningitidis are a public health priority, and their prevention by vaccination is a major objective. Meningococcal capsular polysaccharide-based vaccines are effective against the major invasive serogroups, except for serogroup B, the capsule of which mimics human polysaccharides and is poorly immunogenic. An alternative vaccine candidate that has the potential to offer cross-protection against antigenically diverse meningococci is the lipooligosaccharide (LOS). The structurally constrained peptide mimetic, C22, of a bactericidal antibody epitope within LOS was previously shown to elicit cross-reactive antibodies to meningococcal LOS when complexed to NeutrAvidintrade mark as a carrier protein. The immunogenicity of this antigen in H-2(d) (BALB/c) and H-2(k) (C3H/HeN) haplotype mice was further investigated. Anti-LOS immunoglobulin G (IgG) antibody titres increased with the vaccine dose and correlated with the anti-C22 peptide antibody titres in both haplotypes. Antigen-stimulated Th1/Th2 cytokine secretion by splenocytes and antibody isotypes indicated a Th2-type immune response with IgG1 antibodies and a low titre of IgG2b. There was no serum bactericidal activity observed against the meningococcus.

Animals↗
PubMed1985

Problems in the interpretation of diagnostic tests due to cross-reactions between orbiviruses and broad serological responses in animals.

Tests presently used for the diagnosis of infections by bluetongue virus (BTV) or related orbiviruses are based on the use of 2 types of serological reactions. Those that are considered group-reactive tests are the agar gel diffusion precipitin (AGDP), complement-fixation (CF) and fluorescent antibody tests and those that are considered type-specific are a wide variety of virus neutralization tests (50% and 80% plaque reduction, plaque inhibition and microtiter neutralization) and cross-protection tests. These tests suffer from problems of standardization between laboratories and of specificity. Group-reactive tests (AGDP and CF) for the BTV serogroup also detect cross-reactions with viruses in the epizootic hemorrhagic disease virus (EHDV), Eubenangee (EUB) and Palyam (PAL) serogroups, with the EHDV cross-reactions being of particular concern. Further, multiple infections of cattle with PAL serogroup members can produce antibodies which will react to BTV and EHDV serogroup antigens in serological tests. Multiple infections of animals with related viruses can produce antibodies which will cross-react with orbiviruses in type-specific, virus neutralization tests to a virus which the animal has not previously been exposed. These observations stress the need to evaluate the tests at present being used, to assess the risks of cross-reactions between related orbiviruses and to develop new tests of defined specificity.

Animals↗
PubMed1985

Human antibody response to immunization with 17D yellow fever and inactivated TBE vaccine.

The antibody response against flaviviruses tick-borne encephalitis (TBE), Kyasanur Forest disease (KFD), Murray Valley encephalitis (MVE), West Nile fever (WNF), Japanese B encephalitis (JE), dengue 2 (DEN-2), and yellow fever (YF) was studied in humans after administration of an inactivated TBE virus vaccine. Individuals were either prevaccinated with 17D yellow fever (experimental group) or without any previous exposure to flaviviruses (control group). The appearance of serum titres of homologous and heterologous haemagglutination inhibition (HI) antibodies, heterotypic DEN-2 neutralizing antibodies, and TBE enzyme-linked immunosorbent assay (ELISA) antibodies were examined. Individuals prevaccinated with the 17D yellow fever developed an antibody pattern that contrasted with that of the control group. This pattern was characterized as follows: (1) Predominantly anti-TBE IgG antibodies appeared earlier and in higher titres than in the control group, (2) heterologous HI antibodies cross-reacting with the WN flavivirus subgroup preceded the appearance of homologous HI antibodies, (3) a broad spectrum HI response was observed against all flaviviruses tested, and (4) low titre heterotypic DEN-2 neutralizing antibodies were formed in about half of the cases. These observations are discussed in the context of cross-reactivity, cross-protection and virus infection enhancement.

Antibodies, Viral↗
PubMed2003

Salmonella DNA adenine methylase mutants prevent colonization of newly hatched chickens by homologous and heterologous serovars.

Salmonella mutants lacking DNA adenine methylase (Dam) are highly attenuated for virulence and confer protection against oral challenge with homologous and heterologous Salmonella serovars in mice and chicken broilers. To determine whether vaccines based on Dam are efficacious in preventing early colonization of newly hatched chickens, a Salmonella typhimurium Dam(-) vaccine was evaluated for the protection of chicks against oral challenge with homologous and heterologous Salmonella serovars. Vaccination of chicks elicited protection 2 and 6 days post-challenge as evidenced by a significant reduction in colonization of the gastrointestinal tract (ileum, cecum and feces) and visceral organs (spleen and bursa) when challenged with homologous S. typhimurium. Moderate protection was observed following challenge with heterologous S. enteritidis and Salmonella O6, 14, 24:e, h-monophasic) serovars. These data suggest that Salmonella Dam mutant strains conferred cross-protection, presumably via competitive exclusion mechanisms that prevent superinfection of chicks by other Salmonella strains. Such protection may reduce pre-harvest Salmonella contamination in poultry, decreasing the potential for food-borne transmission of this pathogen to humans.

Animals↗
PubMed1999

Coat-protein-mediated resistance to tobacco mosaic virus: discovery mechanisms and exploitation.

In 1986 we reported that transgenic plants which accumulate the coat protein of tobacco mosaic virus (TMV) are protected from infection by TMV, and by closely related tobamoviruses. The phenomenon is referred to as coat-protein-mediated resistance (CP-MR), and bears certain similarities to cross protection, a phenomenon described by plant pathologists early in this century. Our studies of CP-MR against TMV have demonstrated that transgenically expressed CP interferes with disassembly of TMV particles in the inoculated transgenic cell. However, there is little resistance to local, cell-to-cell spread of infection. CP-MR involves interaction between the transgenic CP and the CP of the challenge virus, and resistance to TMV is greater than to tobamo viruses that have CP genes more distantly related to the transgene. Using the known coordinates of the three-dimensional structure of TMV we developed mutant forms of CP that have stronger inter-subunit interactions, and confer increased levels of CP-MR compared with wild-type CP. Similarly, it is predicted that understanding the cellular and structural basis of CP-MR will lead to the development of variant CP transgenes that each can confer high levels of resistance against a range of tobamoviruses.

Capsid Proteins↗
PubMed2001

Antigen-pulsed dendritic cells expressing macrophage-derived chemokine elicit Th2 responses and promote specific humoral immunity.

Macrophage-derived chemokine (MDC) is a potent chemoattractant for antigen-specific T lymphocytes. We hypothesized that Adenovirus- (Ad-) transduced dendritic cells (DCs) overexpressing MDC would enhance the T cell-mediated humoral immune response specific for antigens presented by the DC. We challenged two strains of mice with lethal Pseudomonas aeruginosa infection 3 weeks after immunization with AdMDC-modified DCs pulsed with heat-killed P. aeruginosa. MDC-expressing DCs specifically attracted T lymphocytes and preserved typical DC surface phenotypes without growth factors in vitro. Mice immunized with AdMDC/Pseudomonas/DCs developed high levels of serum anti-Pseudomonas Ab's and were protected from a lethal respiratory challenge with Pseudomonas. The in vivo protective immunity required CD4(+) T cells, B cells, and IL-4, but not CD8(+) T cells and IL-12. AdMDC/DCs pulsed with Pseudomonas yielded significant but not absolute cross-protection against different strains of P. aeruginosa. Pseudomonas-pulsed AdMDC/DCs protected mice from Pseudomonas but not Escherichia coli and vice versa; this microbe-specific protection correlated with microbe-specific induction of CD4(+) T cell proliferation and IL-4 secretion. Based on these observations, AdMDC-modified DCs pulsed with a killed bacteria may be a useful approach to vaccination against infectious disorders.

Adenoviridae↗
PubMedDate not supplied

Biological activities of crude polysaccharide extracted from two different immunotype strains of Hemophilus gallinarum in chickens.

Biological activities in chickens of crude polysaccharide extracted from two different immunotype strains of Hemophilus gallinarum (HG), strain 221 and S1, were studied to clarify a type-specific protecting antigen and a toxin. Crude polysaccharide materials extracted from strains 221 and S1 were not only protective but toxic to chickens. They also contained at least two heat-labile antigens. When the polysaccharide materials were subjected to gel filtration on Sepharose 6B by tracing at 280 and 490 nm, the protective and toxic activities could be fractionated as peak-1 and -2 polysaccharides, respectively. The fraction of peak-1 polysaccharides from strains 221 and S1 was eluted at void volume. Cross-protection was not found between strains 221 and S1 in the fraction of peak-1 polysaccharide. Hemagglutination-inhibition (HI) antibody to type 1 hemagglutinin of HG (trypsin-sensitive hemagglutinin) was detected in chickens immunized with this fraction from strain 221 but not with that from strain S1. Type specificity between both strains was also found in this fraction by agar-gel precipitation (AGP) test. On the other hand, the toxic fraction of peak-2 polysaccharide, which caused hydropericardium in chickens, had a lower molecular weight than did that of peak-1 polysaccharide. It did not give HI antibody in chickens. Common antigenicity between strains 221 and S1 was found in the peak-2 polysaccharide by AGP test.

Animals↗