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Biomedical subjects

J Knobloch

Publications and source records attributed to J Knobloch.

At least 55 records · Page 3Linked to original sources
PubMed1992

Detection of Bartonella bacilliformis in cultures, blood, and formalin preserved skin biopsies by use of the polymerase chain reaction.

A polymerase chain reaction (PCR) is described for the detection of Bartonella bacilliformis, the etiologic agent of bartonellosis, which cannot be identified biochemically. Amplification of a genomic 231 bp Bartonella DNA sequence permitted specific identification of 12 Bartonella isolates from Peruvian bartonellosis patients as well as detection of Bartonella DNA in blood samples and formaldehyde preserved skin biopsies. Specificity of amplification products was confirmed by restriction fragment analysis. No positive results were obtained with Brucella abortus, phylogenetically closely related to B. bacilliformis, and several other bacterial, fungal, and protozoal species. PCR appears as a promising technique for specific identification of B. bacilliformis in cultures and in clinical materials with further applications in taxonomic studies and in the investigation of Bartonella-like isolates obtained outside South America.

Bacteremia↗
PubMed1992

Isolation of an immunodiagnostic Taenia solium coproantigen.

Antigens of Taenia solium can be demonstrated by ELISA technique in stool samples of tapeworm carriers. In order to isolate these immunodiagnostic components from stool, fecal samples of known T. solium carriers were subject to chromatographic purification procedures: immunoaffinity chromatography and a subsequent two-step high performance liquid chromatography yielded a 60-kDa protein that was shown to react in a Western blot with polyclonal anti-T. solium IgG. The protein isolated appeared to be the major antigenic component excreted with the feces of parasite hosts.

Animals↗
PubMed1991

Detection of Taenia solium antigens in merthiolate-form preserved stool samples.

Cysticercosis can be controlled by mass treatment of Taenia solium carriers in hyperendemic areas. An automated screening method suitable for mass application is required to determine the prevalence of taeniasis and the efficacy of its treatment, since existing methods of carrier detection are considered insufficient for this purpose. Thus, a biotin/avidin-enhanced enzyme-linked immunosorbent assay (ELISA) was designed, which detected T. solium antigens in supernatants of merthiolate-formalin preserved stool samples. The assay distinguished the nine T. solium carriers tested from 41 negative controls, but cross-reactivity with Taenia saginata was noted.

Animals↗
PubMed1990

An epidemic of Oroya fever in the Peruvian Andes.

Between February and October 1987, a febrile illness killed 14 persons and seriously affected at least 14 others in Shumpillan, a remote Peruvian mountain village of 353 people. The illness was characterized by fever, headache, chills, and pallor. The fatality rate of untreated cases was 88%. The patients, 71% of whom were male, were 1-75 years of age. Fatal illnesses progressed from lethargy to coma to death in 3-60 days. Patients treated empirically with chloramphenicol survived. Bartonella bacilliformis was isolated from the whole blood of 3 patients. A serologic study revealed a high prevalence of antibodies to B. bacilliformis in the villagers. It is concluded that the villagers suffered from an epidemic of Oroya fever.

Adolescent↗
PubMed1990

Bb65, a major immunoreactive protein of Bartonella bacilliformis.

A 65 kDa protein (Bb65) has been identified as one of the major specific antigens of Bartonella bacilliformis, the causative agent of bartonellosis which is a bacterial infectious disease of inhabitants of the Andes. The gene encoding this antigen (7B2) was isolated from an expression library made directly from randomly generated fragments of B. bacilliformis genomic DNA using Bartonella antibodies raised in rabbits and sera of bartonellosis patients. The Bartonella 7B2 gene was expressed in Escherichia coli and the recombinant Bb65 protein was purified by column chromatography. Using polyclonal antibodies raised in rabbits, the antigen was shown to be present in all of 13 B. bacilliformis isolates from different Peruvian regions. Immune electron microscopy demonstrated the probable cytoplasmatic localization of Bb65. When applied to enzyme immunoassays, Bb65 sensitively and specifically bound to IgG antibody of sera of bartonellosis patients, convalescents, and immunes from various Peruvian regions. IgM antibody was not recognized by Bb65, neither was IgG antibody circulating during the first 2 weeks of illness. The amino-terminal amino acid sequence of Bb65 was 53% homologous to the 65 kDa heat shock protein of Mycobacterium tuberculosis.

Amino Acid Sequence↗
PubMed1989

Isolation and partial characterization of species-specific and cross-reactive antigens of Echinococcus granulosus cyst fluid.

Two parasite antigens have been isolated from Echinococcus granulosus hydatid cyst fluid using hydrophobic interaction chromatography, anion exchange chromatography and gel filtration chromatography. Initial characterization of the antigens indicates that both are glycoproteins, of approximately 20 and 48 kDa (Eg20 and Eg48). When the two antigens were tested with a battery of antisera from patients with heterologous parasitic infections, only Eg20 was found to be specific for E. granulosus. The Eg48 antigen cross-reacted with the sera of 33% of E. multilocularis patients. In both antigens, some of the epitopes recognized by antibodies in the sera of hydatid patients were periodate-sensitive. This suggests the involvement of carbohydrates in at least some of the antigenic determinants. Due to the abundance of the Eg48 antigen in the hydatid cyst fluid, it would be the more practically useful antigen for disease diagnosis, especially in countries where only E. granulosus is endemic.

Animals↗
PubMed1989

Genomic DNA differences between pathogenic and nonpathogenic Entamoeba histolytica.

cDNA libraries were constructed from pathogenic (HM-1:IMSS) and nonpathogenic (SAW 1734) isolates of Entamoeba histolytica. A cDNA clone (cEH-P1) specific for pathogenic amoebae was identified by screening with a pool of sera from patients with invasive amoebiasis that had been absorbed with nonpathogenic amoebae. This clone was used for the identification of a homologous clone (cEH-NP1) in the cDNA from nonpathogenic amoebae. Sequence analysis and comparison of the predicted amino acid sequences for both clones disclosed 12% evolutionary divergence in structure. Hybridization of both cDNA probes to genomic DNA from four pathogenic and five nonpathogenic E. histolytica isolates revealed two distinct Southern blot patterns, one characteristic for pathogenic amoebae and the other for nonpathogenic amoebae. Further, the complex pattern of restriction fragments hybridizing to an actin cDNA probe was also different between pathogenic and nonpathogenic isolates but was conserved within each group of amoebae. The results indicate that pathogenic isolates of E. histolytica are genetically distinct from nonpathogenic isolates.

Amino Acid Sequence↗
PubMed1988

Antiphagocytic activity of streptococcal M protein: selective binding of complement control protein factor H.

Isolated complement components were used to study the regulation of the alternative complement pathway C3 convertase (EC 3.4.21.47), also called C3b,Bb, on M protein-carrying (M+) and M protein-lacking (M-) streptococci. Neither M- nor M+ streptococci directly affected the formation or dissociation of the surface-bound C3b,Bb or the inactivation of surface-bound C3b by factor I. However, the activity of the serum control protein of the alternative complement pathway, factor H, in controlling streptococcus-bound C3b and C3b,Bb was 6-8 times stronger on M+ organisms than on M- organisms. Furthermore, M+ streptococci of different serotypes and purified streptococcal M6 protein were shown to selectively bind factor H, the dissociation constants ranging from 4.5 X 10(-6) M to 6 X 10(-7) M. We conclude that the antiphagocytic activity of streptococcal M protein may be due to complement inhibition mediated by the binding of factor H. Binding of a regulatory protein appears to be a previously unrecognized route by which a pathogen is able to evade alternative pathway activation.

Antigens, Bacterial↗
PubMed1988

Analysis and preparation of Bartonella bacilliformis antigens.

Twenty-four antigens of Bartonella bacilliformis, a bacterium which causes bartonellosis in residents of high altitude valleys of the Andes, were identified by immunoblot and immunoprecipitation using rabbit anti-Bartonella sera as well as sera of patients. The antigens were designated according to their relative molecular mass which ranged from 16 to 160 kDa. Twelve antigens were detected by antibodies in sera of bartonellosis patients using immunoblot, of which six antigens were detected by immunoprecipitation. Antigens 25, 46, 65, 75, 99, and 160 were identified as probable cell wall antigens. Antigens 50, 65, and 75 detected long-persisting antibodies. Crude Bartonella antigen applied to ELISA reacted with anti-Chlamydia psittaci antibody as well as with antibody of unknown identity in human sera, whereas immunoblot and immunoprecipitation with Triton soluble antigens revealed Bartonella-specific results. Seven Bartonella antigens were prepared by high performance liquid chromatography of which one antigen (48 kDa) reacted Bartonella-specific when applied to ELISA. It was concluded that specificity of antibody determination with crude Bartonella antigen should be confirmed by either immunoblot or immunoprecipitation.

Animals↗
PubMed1988

Common surface epitope of Bartonella bacilliformis and Chlamydia psittaci.

A serosurvey revealed intense cross-reactivity between Bartonella bacilliformis and Chlamydia psittaci. One of the cross-reacting Bartonella antigens was identified as lipopolysaccharide which reacted with Bartonella as well as with Chlamydia serum antibodies. A monoclonal Bartonella antibody bound to Bartonella lipopolysaccharide as well as to the surfaces of Bartonella bacilliformis and Chlamydia psittaci. It was thus demonstrated that Chlamydia psittaci carries a surface epitope identical to an epitope of Bartonella lipopolysaccharide. The lipopolysaccharide was preliminarily characterized by polyacrylamide gel electrophoresis and by a lectin-binding assay. The lipopolysaccharides of Bartonella bacilliformis and Chlamydia psittaci are not identical.

Antibodies, Bacterial↗
PubMed1987

Specific and nonspecific immunodiagnostic properties of recombinant and synthetic Plasmodium falciparum antigens.

Six Plasmodium falciparum/beta-galactosidase fusion proteins produced by a genomic DNA expression library, and two synthetic Plasmodium falciparum antigens were applied to ELISA and tested for their immunodiagnostic properties. Results were compared to reference methods, i.e. fluorescence antibody test with whole cell antigen and ELISA with detergent-soluble crude schizont antigen. Anti-Plasmodium falciparum antibodies could be detected by these molecular antigens to varying extents in human sera. Undesired reactivity to fusion proteins due to the high prevalence of antibodies to beta-galactosidase in human sera and undesired reactivity to one of the synthetic antigens (P12) frequently occurred. The antibodies responsible for the nonspecific reactivity could not be identified. It was concluded that the application of molecular Plasmodium falciparum antigens to ELISA represents a practicable approach to immunodiagnosis of malaria if the construction of epitopes that bind antibodies other than Plasmodium falciparum antibodies can be avoided.

Animals↗
PubMed1987

Detection of homologous and heterologous malaria antibodies by application of Plasmodium falciparum merozoite antigen to an ELISA.

Sera of patients with anti-plasmodial antibodies determined by indirect fluorescence antibody test (IFAT) were used to evaluate an enzyme immunoassay (IgG ELISA) for determining antibodies to Plasmodium falciparum merozoite antigen. The two tests correlated well. Antibodies to species other than P. falciparum, however, were detected by P. falciparum merozoite antigen to a limited extent only.

Animals↗