An intron-containing gene coding for a novel 39-kilodalton antigen of Entamoeba histolytica.
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Biomedical subjects
Publications and source records attributed to G Wiedermann.
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The reactogenicity and immunogenicity of a recently released lot of inactivated hepatitis A vaccine (Havrix) were compared after storage at 37 degrees C for 1 week and at the recommended storage temperature of 2-8 degrees C, in two groups of healthy adults in a randomized, double-blind controlled study. The reactogenicity, geometric mean concentrations and seroconversion rates were all similar in both groups, confirming the good thermal stability of the vaccine.
Clinical and serological responses of infants to primary vaccination with diphtheria-tetanus-acellular pertussis (DTPa) vaccines containing 25 micrograms of filamentous haemagglutinin (FHA) and either 25 or 8 micrograms of pertussis toxoid (PT) were compared in a double-blind randomized study with responses of infants receiving whole-cell pertussis DTP vaccine (DTPw). In total, 308 healthy infants were enrolled to receive three vaccine doses at 3, 4 and 5 months of age. DTPa recipients had significantly lower incidences of local reactions and fever than the DTPw recipients. No differences in reactogenicity were observed between DTPa groups receiving 8 and 25 micrograms doses of PT. After vaccination, an immune response to PT was seen in 96% of 25 micrograms PT DTPa recipients, 94% of DTPw recipients and 86% of 8 micrograms PT DTPa recipients. The geometric mean anti-PT neutralizing antibody titre was significantly higher for 25 micrograms PT dose recipients (34.9 Chinese hamster ovary (CHO)) as compared with 8 micrograms PT dose recipients (21.0 CHO). The results support the use of the higher dose of PT in acellular pertussis vaccine preparations.
In order to evaluate a combination of yellow fever and typhoid fever vaccine, we conducted a controlled trial comparing reactogenicity and immunogenicity of Vi polysaccharide (ViPS) vaccine and yellow fever 17D (YF) vaccine after single, simultaneous and combined administration. The combined YF/ViPS vaccine was prepared by using the liquid ViPS vaccine as a diluent for the YF vaccine. The stability of such a reconstitution had been assessed in vitro. Safety was evaluated using a self-surveillance form and by repeated clinical visits. Immunogenicity was evaluated by a plaque reduction test for YF and by radioimmunoassay for ViPS. Tolerability was satisfactory in all groups. There was no increase in local or general reactions in groups receiving both vaccines, whether given simultaneously or combined. The serological response to ViPS was similar after single and simultaneous or combined administration. Interestingly, the immune response to YF was significantly enhanced in groups receiving the vaccines simultaneously or combined, suggesting a potential adjuvant effect of ViPS.
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BASIC REMARKS: Among travellers to distant countries with a low socioeconomic status and poor hygiene, traveller's diarrhea is a major problem. Once this epidemiological fact had been recognized, intensive efforts were made to reduce the incidence of this illness by prophylactic medication. Among non-antibiotic substances investigated, Saccharomyces boulardii (SB) appeared to show promising results in earlier studies. METHOD: In a placebo-controlled, double-blind study, various dosages (250 mg and 1,000 mg SB) were administered prophylactically to 3,000 Austrian travellers to distant regions. RESULTS: A significant reduction in the incidence of diarrhea was observed, with success depending directly on the rigorous use of the preparation. A tendency was noted for SB to have a varying regional effect, which was particularly marked in North Africa and in the Near-east (Turkey!); in addition, the effect also proved to be dose-dependent. The medication can be classified as low on side effects.
Entamoeba histolytica has an unusual nuclear structure characterized by a low degree of chromatin condensation and the absence of stainable metaphase chromosomes. Although nucleosome-like particles were observed, no information about histones was available so far. In this paper we describe a cDNA clone with significant homology to H3 histones that was isolated from a library of pathogenic E. histolytica. The complete cDNA encodes a 15-kDa polypeptide, which like the histone sequence from Volvox carteri is shorter by one residue than the human homologue. The amino acid sequence has only 69% identity with human H3.3 histone and 67% identity with the human H3.1 histone. This is the highest degree of sequence divergence observed for any eukaryote H3 histone sequence. Our results indicate that this divergence may contribute to the unusual chromatin structure of E. histolytica.
Physicians dealing with prophylactic measures for tourists going to developing countries will often not be able to foresee the outcome of their recommendations. Therefore an open study with 2,627 Austrian tourists on their flight home from a tropical destination was carried out to evaluate the behaviour of typical short-term travellers with respect to different kinds of precautionary measures. 94.1% of all tourists informed themselves before travelling abroad, but a high proportion of travellers tends to contact only their travel agency or their personal friends, this leading to inadequate information. Regarding the individual performance of precautionary measures the results indicate a few principal conclusions: Among the recommended inoculations the vaccinations against typhoid fever, poliomyelitis and tetanus are widely underestimated, the latter two in particular for adults, while compliance with the passive immunization against Hepatitis A is generally good (more than 80% of all travellers receive Hepatitis A immunoglobulins prophylactically). The most crucial point seems to be the chemoprophylaxis against malaria in as much as a) there seems to be a considerable lack of information about malaria endemic areas among physicians, b) tourists tend to use the most simple applicable drug unaware of epidemiological considerations and c) the regular intake of chemoprophylaxis declines significantly with the complexity of the intake procedure. In addition, tourists are in general well informed about nutritional risks, but only half of them will receive adequate information on the risk of sexually transmitted diseases and a basic medical travel kit.
In order to investigate the humoral immune response against Entamoeba histolytica a lambda ZapII cDNA library was constructed from trophozoites of the pathogenic E. histolytica strain SFL-3. The library was screened with serum IgG from a patient with invasive amoebiasis. Forty-nine immunopositive lambda clones were isolated and partial sequences from the inserts were obtained. By comparison of the sequences with the merged database MIPSX from the Martinsried Institute for Protein Sequences we were able to identify homologous proteins for 36 of the clones. Twenty-six of the clones encoded intracellular proteins, among these, the major part (16 clones) were highly homologous to the eukaryotic 70-kDa heat shock proteins (Hsps). The open reading frame of one complete clone encodes a protein of 656 amino acid residues of 71.5 kDa which has 69.8% sequence identity with the human Hsp70 protein. In a larger screening experiment only 3 out of 12 patients detected with their IgG the phage which expressed the 70-kDa heat shock protein(s).
A level of 10 mIU hepatitis A antibodies/ml as measured by ELISA is believed to be the minimal protective concentration. If this level is considered, the mean persistence of vaccine induced antibodies is approximately 10-11 years after booster dose, 6-7 years if only the primary doses are given and 5-6 years if the minimal individual titre is taken into account.
Hepatitis A and hepatitis B are endemic in many countries and must be considered as serious health risks for large parts of the world population. Simultaneous or combined vaccination against these two diseases would therefore be most advantageous. In order to investigate possible interactions between these vaccines with respect to their tolerability and immunogenicity, we conducted a randomized prospective study comparing single and simultaneous administration of the two vaccines. Three groups of healthy volunteers, each with 55 persons, were included in the study. All were negative for hepatitis A and hepatitis B markers and had normal serum liver enzyme values. Group I received hepatitis A vaccine (720 ELISA units) into the left deltoid muscle, group II received hepatitis B vaccine (20 micrograms) into the right deltoid muscle and group III received hepatitis A vaccine into the left, and hepatitis B vaccine into the right deltoid muscle. Three doses of the vaccines were administered at 0, 1 and 6 months. Local and systemic reactions were monitored by means of questionnaires. Blood samples for determination of antibody to hepatitis A virus (anti-HAV) and antibody to hepatitis B surface antigen (anti-HBs) and of serum SGOT and SGPT levels were drawn at months 0, 1, 2, 6 and 7. There were no serious general and only mild local reactions. The mean serum SGOT and SGPT values remained in the normal range in all groups. The seroconversion rates and mean geometric titres of the anti-HAV and anti-HBs antibodies were similar when the vaccines were administered separately or simultaneously. There were no significant differences between the compared groups.(ABSTRACT TRUNCATED AT 250 WORDS)
E. histolytica has an unusual nuclear structure. Although nucleosome-like particles were observed, no information about histones was available so far. In this paper we describe a cDNA clone with significant homology to H3 histones that was isolated from a lambda Zap library of pathogenic E. histolytica. The complete cDNA encodes a 15 kDa polypeptide, which is shorter by one residue than the human homologue. The amino acid sequence has only 69% identity with human H3.3 histone. Our results indicate that this divergence may contribute to the unusual chromatin structure of E. histolytica.
Several surface IgG antigens of E. histolytica have been characterized. We isolated two novel cDNAs by screening a library of pathogenic E. histolytica with rabbit antiserum against a membrane preparation of pathogenic amebas. cDNA K15 encodes a large protein > 220 kDa with sequence homology to myosins and K18 encodes a protein of around 40 kDa. Serum IgG from patients suffering from amebiasis binds to both antigens. Some IgE antibodies are able to recognize homologous proteins in all eukaryotes investigated. We demonstrate that IgE antibodies from pollen allergic patients bind to plant, human, as well as E. histolytica profilins.
Paired samples of stool and serum of 32 members of the Shipibo tribe resident in the rain forest of the Peruvian lowlands were tested for worm egg count and serum lipid parameters, respectively. 90% of the stool samples tested were found to contain eggs or larvae of several worm species, most commonly 3 or 4 different species. Serum lipid levels were found to be relatively low, most probably due to a low proportion of dietary fat ranging from 16-31%. Statistical analysis showed a significant inverse correlation between worm egg excretion and HDL levels which was true for hookworm, strongyloides and trichuris, but not for ascaris. The mechanisms underlying the observed association between intestinal worm load and HDL reduction are not completely understood and may include reduced HDL synthesis in the gut wall due to inflammatory and/or toxic irritation.
In March 1991 the Supreme Board of Health issued new recommendations for immunization of children which are basically similar to those issued in 1989, but were partially reformulated. Again, BCG vaccination is not generally recommended and should be given only to individuals at high risk of contracting the disease. It is therefore not listed any more in the general recommendations (A) but only mentioned under special vaccinations (B). Special indications for BCG vaccination were clearly reformulated. Vaccinations against diphtheria-tetanus or pertussis-diphtheria-tetanus are recommended as usual, an oral pertussis vaccine is presently not available and an acellular pertussis vaccine is under study. Booster vaccinations at school entry will be performed with a low dose of diphtheria-toxoid to avoid local side reactions.
Acellular pertussis vaccines contain antigen components of B. pertussis, usually lymphocytosis promoting factor (LPF) which is also called pertussis-toxin (PT) or pertussigen, filamentous hemagglutinin (FH) and, eventually, agglutinogens 2 and 3. Acellular vaccines are being used in Japan since 1981. Several Phase II studies have been performed and showed a better tolerability than whole cell vaccines and antibody responses of at least equal magnitude. In some of these studies good protection rates were observed. The latter were not satisfactory in a Phase III study in Sweden. This study, however, might cause some criticism in as much as only 2 vaccine doses were given and a control group with whole cell vaccine was missing. Moreover, the significance of bacterial infections in vaccinated children is doubtful, similar observations have not been made in other trials nor in Japan since introduction of the vaccine in 1981. Preliminary results of our own study with a newly developed acellular vaccine which has been permitted by the Austrian Drug Commission have shown good tolerability.
The reactogenicity and immunogenicity of a formaldehyde-inactivated hepatitis A vaccine have been investigated. Three different dose levels of vaccine (180, 360 and 720 ELISA units) were administered to healthy volunteers according to a 0, 1, 2 and 12 month schedule. The vaccine was safe and well tolerated. Reactions observed following vaccination were essentially mild and were not dependent upon the quantity of antigen administered. All subjects had measurable titres of anti-HAV antibodies after the full vaccination course; the immune response to the vaccine was dose-related. Antibody titres in vaccinees at month 13 were between 60- and 190-fold higher than those observed in a group of subjects given anti-HAV immunoglobulin.
Immunohistological studies of tuberculoid leprosy lesions (TT-lesions) showed a dense, well organized granuloma consisting of a central area with epitheloid and giant cells containing interferon-gamma (IFN-Gamma) and CD3+, CD4+ T helper/inducer (Th/i) cells, a considerable proportion of which expressed the interleukin-2-receptor (IL-2 R). This central area was surrounded by round cells which consisted mainly of CD3+/CD8+ T cytotoxic/suppressor (Tc/s) lymphocytes. The overlying keratinocytes (KC) were strongly positive for HLA-DR antigens on the surface, indicating high intralesional IFN-Gamma activity. In contrast, lepromatous leprosy lesions (LL-lesions) showed a disorganized infiltrate composed by foamy cells and round cells, the latter mainly expressing the CD3+/CD8+ phenotype. IFN-Gamma activity could not be detected within the lesions. The KC overlying the infiltrate were consistently negative for HLA/DR reactivity pointing to a defective intralesional IFN-Gamma production in LL patients. Two out of four patients with LL leprosy could be sensitized with dinitrochlorobenzene (DNCB). The eliciting of DNCB skin reactions within the LL-lesion led to the recruitment of new infiltrating cells; the resulting infiltrate resembled a local reversal towards the tuberculoid pole of leprosy.