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PubMed2004

Radiation resistance and virulence of Listeria monocytogenes Scott A following starvation in physiological saline.

The influence of starvation on the resistance of Listeria monocytogenes Scott A to electron beam irradiation in 0.85% (wt/vol) NaCl (saline) and in ground pork was investigated. Exponential- or stationary-phase cells (control) were grown at 35 degrees C in tryptic soy broth supplemented with 0.6% yeast extract. Washed cells were starved for 12 days in saline, and virulence of the pathogen was evaluated at 0, 8, and 12 days during starvation. Samples of saline and irradiation-sterilized ground pork, inoculated with control or starved cells, were irradiated at doses ranging from 0.0 to 2.5 kGy. L. monocytogenes survivors were determined by plating diluted samples of saline or pork on tryptic soy agar supplemented with 0.6% yeast extract and counting bacterial colonies following incubation (35 degrees C, 48 h). Virulence of starved cells and control was not significantly different (P > 0.05). Cells exhibited the highest radiation resistance at 8 days of starvation. Irradiation (0.5 kGy) in saline resulted in approximately 7.14, 5.55, and 2.38 log reduction in exponential, stationary, and starved cells, respectively. Irradiation of ground pork at 2.5 kGy reduced controls by approximately 6.0 log, whereas starved cells were reduced by only 3.8 log. Starved cells consistently exhibited higher irradiation D10-values than controls (P < 0.05). D10-values for exponential, stationary, and starved cells were 0.07, 0.09, and 0.21 kGy and 0.35, 0.42, and 0.66 kGy in saline and ground pork, respectively. These results indicate that starvation cross-protects L. monocytogenes Scott A against radiation inactivation and should be considered when determining this pathogen's irradiation D-value.

Adaptation, Physiological↗

PubMed2005

Growth history influences starvation-induced expression of uspA, grpE, and rpoS and subsequent cryotolerance in Escherichia coli O157:H7.

In this study, we investigated the effect of starvation on cryotolerance of Escherichia coli O157:H7 grown in tryptic soy broth (TSB) and Luria-Bertani broth (LB). Starved cells (cells suspended in water at 37 degrees C for 6 h) and control cells (cells in TSB or LB) were frozen at -18 degrees C for up to 240 h in their respective growth media. The E. coli grown in TSB showed a greater starvation effect (the difference in percent survival of starved and control cells) and cryotolerance. The starved E. coli grown in TSB showed a 30% increase in their ability to survive frozen storage for 24 h at -18 degrees C. The corresponding increase in survival for LB-grown E. coli was only 3.8%. Cryotolerance induced by starvation of TSB- and LB-grown E. coli was correlated with the expression of genes involved in general stress response pathways, such as uspA, grpE, and rpoS. The expression of uspA, grpE, and rpoS was quantified by measuring the green fluorescence generated from autofluorescent E. coli harboring puspA::gfp, pgrpE::gfp, and prpoS::gfp gene fusions. The results obtained in this study indicate that uspA, grpE, and rpoS were induced on starvation when E. coli was grown in TSB, and their expression correlated well with subsequent induction of cryotolerance developed at -18 degrees C. In contrast, cells grown in LB and subsequently exposed to starvation conditions showed no increase in expression of uspA, grpE, or rpoS, and, as expected, these cells did not exhibit increased cryotolerance at -18 degrees C. Knowledge of molecular mechanisms involved in cross-protection might make it possible to devise strategies to limit their effects and lead to ways to predict the survival of foodborne pathogens in stressful environments.

Adaptation, Physiological↗

PubMed1999

Enhancement of graft-versus-tumor activity and graft-versus-host disease by pretransplant immunization of allogeneic bone marrow donors with a recipient-derived tumor cell vaccine.

Allogeneic bone marrow transplantation (BMT) can be accompanied by a beneficial T cell-mediated antitumor immune response known as graft-versus-tumor (GVT) activity. However, BMT donor T cells are not exposed to target antigens of GVT activity until transfer to the host, where tumor antigen presentation may be suboptimal. This study tested in a murine model the hypothesis that immunization of MHC-matched allogeneic donors with a recipient-derived tumor cell vaccine would substantially increase GVT activity and extend survival of BMT recipients with preexisting micrometastatic tumor. C3H.SW and C57BL/10 mice were immunized against a C57BL/6-derived fibrosarcoma or leukemia, and they were used as BMT donors. Recipients were H-2-matched, minor histocompatibility antigen-mismatched C57BL/6 mice with previously established micrometastatic tumors. Donor immunization led to a significant increase in GVT activity that was T cell dependent and cell dose dependent. In some settings, donor immunization also prolonged survival of recipients with preexisting micrometastatic tumors. However, donor immunization significantly increased the incidence of fatal graft-versus-host disease such that long-term survival was uncommon. In vitro cytotoxicity assays indicated that donor immunization induced both tumor-selective and alloreactive cytolytic T-cell populations. In vivo cross-protection assays showed that a substantial portion of the GVT effect was mediated by alloreactive cells not specific for the immunizing tumor. In conclusion, immunization of allogeneic BMT donors with a recipient-derived whole tumor cell vaccine substantially increases GVT activity but also exacerbates graft-versus-host disease.

Animals↗

PubMed1998

Formaldehyde as a proof and response to various kind of stress in some Basidiomycetes.

The influence of cadmium chloride and/or high temperature on the level of selected parameters were examined in both medium and mycelium of some Basidiomycetes belonging to white-rot fungi: Abortiporus biennis, Trametes versicolor and Cerrena unicolor. We investigated changes in the formaldehyde (FA) level and in the level of superoxide radical anions (SR). Accordingly, the capacity of three enzymes was also studied: two enzymes of the cellular antioxidative system - superoxide dismutase (SOD; EC 1.15.1.1), and catalase (CAT; EC 1.11.1.6), and laccase (LAC; EC 1.10.3.2) the main lignin-modifying enzyme, which is produced by white-rot fungi. During the first 24 hours after application of separate stressors, or jointly with two stressors to 10-day-old cultivation, changes in all selected parameters were observed. Moreover, we found significant changes in the levels of extracellular SR, FA and extra- and intracellular activity of LAC. Simultaneous action of two stressors in the fungal cultures decreased the extracellular LAC level, intracellular CAT activity and the level of SR in the medium compared to the control values, while using the two stress factors separately would strongly make these values increase. Stressful conditions brought a rapid increase in the level of FA in all fungal species. The results of our study, carried out on selected strains of Basidiomycetes, seem to have shown that: (I) LAC, the lignin-modifying enzyme, may have an important application in fungal stress response, and take part in the cross-protection between responses to heat shock and cadmium resistance; (2) the oxidative burst as a result of cadmium and high temperature treatment is an additional factor to damage fungal cells; (3) FA may be a determining factor in the phases of fungal stress syndrome.

Basidiomycota↗

PubMed2000

[Assessment of malaria DNA vaccines in mice and monkeys].

Cholera toxin B subunit is a good carrier protein and an effective adjuvant which can boost both cellular and humoral immunity. DNA fragments encoding B cell, Th cell and CTL epitopes of P. falciparum CS, MSA-1, MSA-2 and RESA antigens were cloned down-2 stream of cholera toxin B subunit gene in the same reading frame. High titer of anti-malaria epitopes antibodies and strong cellular immunogenicity were elicited after Balb/c mice were immunized three times with 100 micrograms recombinant plasmid DNA dissolved in 100 microliters PBS. A total of 120 vaccinees were challenged with mouse Plasmodium yoelli to investigate if cross protection existed. The protective efficacy was about 60%-80%. Four rhesus monkeys were challenged with 10(8) of P. cynomalgi, better results were obtained in the groups immunized with mixed plasmids including NANP, AWTE.

Animals↗

PubMed1975

Bovine infectious keratoconjunctivitis: carrier state of Moraxella bovis and the development of preventive measures against disease.

Bovine infectious keratoconjunctivitis, which is caused by Moraxella bovis, occurs perennially in all cattle-raising areas. Disease may occur any time during the year but manifests itself often during summer when disease-enhancing factors such as ultraviolet radiation and fly population are increased. Although some recent research findings indicate that cattle can be immunized against the disease, many problems have to be overcome before the cattle industry can benefit from such immunization. Some pressing problems relate to lack of cross-protection between vaccines of different strains of M bovis, resistant or resilient carrier states, and how these factors affect vaccination regimens undertaken. Though cattle vaccinated with 1 strain are somewhat protected against subsequent challange by the same strain, protection against heterologous strains has not been demonstrated. In most herds, cattle harbor M bovis, and these carriers may serve as a source of infection.

Animals↗

PubMed1975

Immunization of mice and guinea-pigs against Salmonella dublin infection with live and inactivated vaccine.

The immunogenicity of a number of avirulent rough Salmonella dublin mutants was compared in mice and guinea-pigs. Live vaccine prepared from Strain HB 1/17 at doses of 5 X 10(7) per mouse usually gave an immunity of between 70 and 80% but in certain experiments the results were more variable and always poorer. This strain gave a cross protection of 28,5% to S. typhimurium in mice. In guinea-pigs it evoked an average protection of approximately 46% to homologous challenge and approximately 26% to challenge with S. tryphimurium. Strain 5765 protected up to 80% of mice against S. dublin infection and was generally superior to Strain HB 1/17 in this respect. It was, however, less effective in protecting mice against S. tryphimurium (20%). In guinea-pigs it was also less effective than Strain HB 1/17, giving 34% protection against homologous and 20% against heterologous challenge. Other strains also produced immunity in mice but they were not studied in detail. Formalin-inactivated alum-precipitated vaccine prepared from avirulent smooth strain and containing 0,5% packed cells proved to be extremely effective in protecting mice against S. dublin infection. It produced an average immunity of 75% and was often 100% effective. It also protected 60% of mice against challenge with S. tryphimurium. In guinea-pigs it was, however, totally ineffective against challenge with both S. dublin and S. tryphimurium.

Animals↗

PubMed2002

The classification of seven serotypes of equine encephalosis virus and the prevalence of homologous antibody in horses in South Africa.

Selected isolates of equine encephalosis virus were shown to have comparable viral protein profiles and to represent seven distinct serotypes, based on cross-neutralization tests. Serotype-specific virus-neutralizing antibody in serum samples from horses confirmed the widespread occurrence of infection. The distribution and prevalence of individual serotypes however, varied considerably. Localised foci with an increased seasonal seroconversion in groups of horses to a specific serotype and the detection of an ongoing low level of infection from other serotypes within the population, confirmed the independent persistence of the viruses in a maintenance cycle. The identification of donors with antibody resulting from infection with multiple serotypes indicated a low level of cross-protection in horses to natural reinfection.

Animals↗

PubMed2002

[Haemophilus influenzae type a as the causative agent of meningitis in an infant].

A 6-month-old girl had been ill with a cold for several days and was increasingly drowsy. She had been fully vaccinated against Haemophilus influenzae type b and had meningitis due to H. influenzae type a. She made a complete recovery after treatment with ceftriaxone and amoxicillin. In the Netherlands, vaccination with the conjugated H. influenzae type b vaccine was started in 1993 and since then invasive infections caused by H. influenzae type b have almost disappeared. Vaccination may suppress carriership of H. influenzae type b. However, vaccination does not elicit cross-protective antibodies against other serotypes of H. influenzae. H. influenzae non-type b may profit from the vaccination state, resulting in a higher carrier rate and an increased incidence of invasive infections. In the Netherlands, H. influenzae type a as the causative agent of an invasive infection has been recorded for the first time since registration started in 1975 and since then five such cases have been reported. In the literature, 45 cases of infection with H. influenzae type a have been described up until now.

Amoxicillin↗

PubMedDate not supplied

[Common stressor proteins in bacteria].

Research data on common stressor proteins of bacteria obtained during recent 10 years are updated and analyzed. Bacteria of one and the same species were shown to give similar response to the action of different stressors; the main stressor proteins of different bacteria appeared to be homologous; bacteria have cross protection from different stressors. In addition, some common stressor proteins of bacteria were found to be homologous with human antigens that is of great importance for immunobiotechnology.

Bacteria↗

PubMed2002

Mumps virus reinfection--clinical findings and serological vagaries.

Sera taken from two cases of mumps reinfection were tested against different strains of mumps virus in a plaque reduction neutralisation assay. Antibodies to mumps in the sera reacted with all strains, but the pattern of emergence of these antibodies differed with the strains tested. These findings raise the possibility of emergence of a mutant strain under the selective pressure of immunisation, with limited or no cross protection induced by the vaccine strain.

Adult↗

PubMed2001

[Immunity against Schistosoma japonicum induced by phage display peptides mimicking antigenic epitopes of Trichinella spiralis].

OBJECTIVE: To obtain the short peptides mimicking antigenic epitopes of Trichinella spiralis (T. s.), and explore their cross protective immunity against Schistosoma japonicum (S.j.) in mice. METHODS: IgG antibodies were purified from sera of mice infected with T.s.. The purified IgG was used to immunoscreen a phage random peptide library of 7 amino-acid residues displayed as a fusion to protein of filamentous phage. Positive clones were obtained by affinity selection, the reactivity of each clone binding to specific IgG was detected by ELISA. Kunming mice were immunized subcutaneously three times with mixed phage clones. The mice were sacrificed 45 days after challenge. The worms and the liver eggs were counted. RESULTS: After three rounds of panning, the relevant phages had been enriched approximately 150 times in production as compared to those from the first round. Of 24 phage clones randomly selected from the third round biopanning, 21 clones were shown to actually bind to the specific IgG. As compared with the control group, the worm and the liver egg reduction rates in vaccination group were 42.8% and 66.3% (P < 0.001), respectively. CONCLUSION: The above results demonstrate that antigenic epitopes of T. s. can be prepared by immunoscreening phage random peptide library and a significant protective immunity against S. j. can be induced by these epitopes in mice.

Animals↗

PubMed1976

Efficacy studies on Haemophilus gallinarum bacterin preparations.

Broth cultures inactivated and potentiated by selected methods were tested in chickens for efficacy against homologous and heterologous challenge inoculation, using 2 serotype A strains of Haemophilus gallinarum. Although the 2 strains were within the same serotype, they failed to cross protect. One dose of thimerosal-inactivated bacterin was protective against homologous challenge, but 2 doses of formalin-inactivated bacterin were required. A bivalent bacterin protected chickens well against 1 strain, but not the other, at the 1-dose level.

Animals↗

PubMedDate not supplied

[Mucosal viral vaccines: progress and problems].

Data obtained in the recent years on developing the viral inactivated mucosal vaccines by applying the mucosal-adhesive adjuvants are presented in the survey. Progress achieved in designing the mucosal influenza vaccines and mucosal vaccines against a variety of other viral infections is pointed out. Cross-protection against variations of a virus within its subtype limits as well as overcoming of a negative influence of parent antibodies produced on the immunogenicity of live-vaccines', which were used at young age, were observed in the intranasal administration of viral mucosal vaccines. A number of shortcomings of bacterial toxins used as mucosal-adhesive adjuvants as well as problems, which may arise when the viral mucosal vaccines are used on a large-scale basis due to a need in their two- and-threefold intranasal administration, are in the focus of attention.

Adhesives↗

PubMedDate not supplied

[Development of mucosal influenza inactivated vaccines].

In this review recent data on the development of mucosal influenza inactivated vaccines with the use of mucosoadhesive adjuvants are presented. After the intranasal administration of such vaccines the formation of not only systemic, but also local immunity (IgA antibodies), as well as cross protection against the variants of influenza virus within its serotype, can be observed. Some mucosal influenza vaccines have passed clinical tests. Certain drawbacks of Escherichia thermolabile enterotoxin, used as mucosoadhesive adjuvant, and difficulties which may arise in mass immunization with mucosal vaccines due to the necessity of introducing them in two or three intranasal administrations are indicated.

Adjuvants, Immunologic↗

PubMed1961

Studies of scorpion antivenins. 1. Paraspecificity.

This paper describes neutralization tests conducted to determine the effectiveness of five commercially available antivenins, each from a different geographical area, in neutralizing homologous and heterologous scorpion venoms. Venoms of eight scorpion species were used. The work was undertaken because of current interest in the development of polyvalent antivenins for the treatment of venomous bites and stings, and for determination of paraspecific action of existing antivenins as a first step in such a developmental programme. During the studies described, several instances of cross-protection were found, and in some tests heterologous antivenins were more effective than homologous antivenins in protecting white mice against the effects of venom injections. The results obtained should be of practical value in planning a systematic approach towards production of a polyvalent antivenin for use anywhere in the world.

Animals↗

PubMedDate not supplied

Pathologic and serologic characterization of a variant of duck hepatitis type I virus.

A duck hepatitis virus (DHV), isolated from ducks on a farm in Virginia in 1963, was shown to be only partially related to DHV type I (DHV-I) in cross-neutralization and in cross-protection tests. The virus, named DHV-Ia, apparently is a serologic variant of DHV-I; both viruses are serologically distinct from DHV type III. Pathologic responses to DHV-Ia were similar to those described for DHV-I infection.

Age Factors↗

PubMed1992

Susceptibility of dogs to infection with Ehrlichia chaffeensis, causative agent of human ehrlichiosis.

Ehrlichia chaffeensis, the newly recognized agent of human ehrlichiosis, is closely related to E canis, the causative agent of canine ehrlichiosis. Eight pups were inoculated IV with E chaffeensis-, or with E canis-infected DH82 cells, or organisms released from these host cells. Two additional pups served as nonexposed controls. Marked thrombocytopenia was observed in the E canis-infected pups, but not in those infected with E chaffeensis. Homologous serologic response was observed in the E chaffeensis-exposed pups by postinoculation day (PID) 14 and in the E canis-exposed pups by PID 21. Ehrlichia chaffeensis and E canis were reisolated from the respective inoculated pups on each of 8 attempts from PID 7 to 26. One E chaffeensis-exposed pup that was challenge exposed with E canis via blood transfusion, developed fever, anorexia, and thrombocytopenia, suggesting lack of cross protection against E canis.

Animals↗