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Biomedical subjects

R B Gasser

Publications and source records attributed to R B Gasser.

157 records · Page 9Linked to original sources
PubMed1991

Antibody responses against natural Taenia hydatigena infection in dogs in Kenya.

Antibody responses (IgG) against Taenia hydatigena infection in dogs in Kenya were analysed in ELISA using excretory/secretory products of T. hydatigena scoleces derived from goat cysticercus cysts. Helminth infections of individual dogs were confirmed at autopsy. T. hydatigena worms were found in 89.5% of 143 dogs, and positive anti-T. hydatigena antibody levels were detected in 58.7% of infected dogs. Positive antiscolex antibody levels were detected in 40.0% of Turkana dogs uninfected with T. hydatigena, suggesting previous infection. Antibody was not detected in 34.4% of infected dogs. There was no relationship between individual T. hydatigena worm burdens and absorbance values for sera in ELISA. It was not possible to distinguish between sera from T. hydatigena-infected and uninfected dogs.

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PubMed1991

Echinococcus granulosus: antigenic proteins in oncospheres and on the surface of protoscoleces identified by serum antibodies from infected dogs.

Proteins present in oncospheres and on the surface of living protoscoleces of Echinococcus granulosus were radioiodinated by the lodogen technique and immunoprecipitated with sera from dogs with E granulosus infection and several categories of control sera. Analysis of immunoprecipitates was performed using sodium dodecyl-sulphate polyacrylamide gel electrophoresis to identify antigenic protein components specific for E granulosus. Sera from dogs with E granulosus infection identified antigenic proteins of around Mr 37,000, 30,000 or 22,000 in oncospheres, and proteins of around Mr 70,000, 43,000, 36,000, 27,000 (triplet), 20,000 or 14,000 on the surface of protoscoleces. These antigens appear to be both species- and stage-specific and may be useful for serological discrimination between 'current' and 'recent past' prepatent and patent E granulosus infections in dogs.

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PubMed1990

A recombinant antigen with potential for serodiagnosis of Echinococcus granulosus infection in dogs.

Antibodies specific for Echinococcus granulosus were affinity purified from dog serum on transfer blots containing putative serodiagnostic antigens. These antibodies and serum pools derived from dogs with E. granulosus infections were used to screen a lambda gt11 cDNA library constructed using E. granulosus protoscolex mRNA. Nine definitive antigenic clones were isolated and characterized, of which one (c10P1) gave strong specific reactions in plaque immunoassay with sera from E. granulosus infected dogs. These clones were all subcloned into the plasmid vector pGEX-1. Antigenicity of clones was confirmed in colony immunoassay and/or immunoblot. Glutathione S-transferase (GST) fusion proteins of individual subclones were produced in Escherichia coli, purified by affinity chromatography and evaluated in ELISA using sera from dogs with infections of E. granulosus, Taenia spp. or nematodes, and helminth-free dog sera. The GST fusion protein 10P1 showed a specificity of 100% in ELISA for diagnosis of E. granulosus infection in dogs despite its relatively low sensitivity. Further investigations aim to identify additional recombinant antigens and test 10P1 expressed in alternative expression systems to increase diagnostic sensitivity of the ELISA.

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PubMed1989

Identification of protein components of Echinococcus granulosus protoscolex antigens for specific serodiagnosis of E. granulosus infection in dogs.

Proteins of Echinococcus granulosus protoscolex excretory/secretory or deoxycholate solubilized somatic antigens were radiolabelled with 125I and immunoprecipitated with sera from dogs naturally or experimentally infected with E. granulosus and various control dog sera. Analysis of immunoprecipitates was performed using one- and two-dimensional gel electrophoresis to identify antigenic protein components specific for E. granulosus. Using both electrophoretic techniques, a basic component of Mr 27,000 and an acidic component of Mr 94,000 were defined in both excretory/secretory and somatic protoscolex antigens, and were specifically identified by 95% and 62% of 21 sera from E. granulosus-infected dogs, respectively. An abundant component of Mr 35,000 was identified by 100% of these dogs, parts of which were E. granulosus specific. Results of this study should allow identification of specific recombinant antigens for routine serodiagnosis of E. granulosus infection in dogs.

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PubMed1988

Evaluation of a serological test system for the diagnosis of natural Echinococcus granulosus infection in dogs using E. granulosus protoscolex and oncosphere antigens.

Serum antibody responses in feral or domesticated dogs naturally infected with Echinococcus granulosus or/and other common helminths were examined in an enzyme-linked immunosorbent assay (ELISA) using antigens prepared from E. granulosus protoscoleces or oncospheres. The ELISA using the protoscolex antigen was optimised with serums from experimental dogs monospecifically infected with E. granulosus or other helminth parasites, and helminth-free dogs. Anti-protoscolex antibody was detected in 16 of 22 (72.7%) serums from feral dogs with E. granulosus burdens ranging from 300 to 302,600 worms per dog. Seven serums from feral dogs which did not harbour E. granulosus at autopsy but which originated from an endemic hydatid region were tested using protoscolex antigen, and 1 serum gave a positive reaction. One hundred and two serums from dogs known never to have been infected with E. granulosus all gave negative reactions to protoscolex antigen. The sensitivity of the ELISA test proved to be superior to that which has been achieved by arecoline purging as a method of diagnosis for E. granulosus infection in dogs. For use of the assay in hydatid control or eradication campaigns, its sensitivity can be increased by choosing a lower absorbance discrimination value above which serums are regarded as having positive reactions. However, this does introduce positive reactions of some serums from dogs infected with helminths other than E. granulosus. In further development of the assay, use of defined recombinant antigens may improve both sensitivity and specificity.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1987

Infectivity of Swiss Giardia isolates to jirds and mice, and in vitro cultivation of trophozoites originating from sheep.

The susceptibility of Giardia-free jirds (Meriones unguiculatus) and AJ-strain mice to oral inoculation with cysts from Swiss Giardia isolates was assessed. Giardia cysts of human, dog, cat, and sheep origin produced infections in jirds (4-10 weeks old). AJ-strain mice (6 weeks old) were insusceptible to Giardia from man, dog, and cat. The number of Giardia cysts inoculated per rodent ranged from 5000 to 12,600. The course of infection was studied in jirds experimentally infected with a Giardia isolate of cat origin. After administration of 6300 cysts to each of 16 jirds, 5 (31%) started to excrete cysts 4-5 days post inoculation (p.i.). Cyst excretion patterns were mostly intermittent, patency periods lasted 5-28 days, and average cyst numbers per g feces of individual jirds varied between 118,500 and 835,200 (maximal number: 3216700). The parasites were eliminated spontaneously in all 5 jirds. The Giardia isolate of cat origin was passaged 4 times in the jird. A Giardia isolate obtained from sheep was transferred in the cyst stage to jirds. Giardia trophozoites isolated from one of these jirds have been axenically cultivated in vitro in a modified, filter-sterilized TYI-S-33 culture medium and successfully cryopreserved. To our knowledge, this is the first report on axenic cultivation of Giardia of sheep origin. Giardia from cats could not be cultivated in vitro under the same conditions. The fact that Swiss Giardia isolates from humans and various domestic animals are not strictly host-specific is in agreement with similar findings from other areas and suggests a zoonotic character for giardiasis.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMedDate not supplied

Screening for different genotypes of Echinococcus granulosus within China and Argentina by single-strand conformation polymorphism (SSCP) analysis.

Single-strand conformation polymorphism (SSCP) analysis was employed for the direct visual display of genetic variability in mitochondrial DNA (mtDNA) fragments within and among populations of Echinococcus granulosus from the People's Republic of China and from Argentina. Fragments of the NADH dehydrogenase I gene (NDI) and the cytochrome c oxidase subunit I (COI) were individually amplified from parasite DNA by polymerase chain reaction, denatured and subjected to SSCP analysis. Using NDI and COI fragments, samples representing different genotypes could be readily identified based on characteristic SSCP profiles. The results demonstrate the utility of SSCP for the direct visual display of nucleotide variation in mtDNA of E. granulosus prior to DNA sequence analysis. The approach compares favourably with existing genotyping procedures and provides a reliable and technically reproducible method for the routine laboratory identification of Echinococcus isolates.

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PubMedDate not supplied

Central nervous system toxoplasmosis in Roller canaries.

Several birds in a flock of 40 Roller canaries (Serinus canaria) from an outdoor aviary in Victoria, Australia, developed central nervous system signs that included blindness, nystagmus, ataxia, and head rotation. Four died, and four were euthanatized. Two euthanatized birds were submitted for microscopic examination of tissues. Brain lesions in both birds consisted of scattered foci of nonsuppurative meningoencephalitis with gliosis, mild to moderately extensive lymphocytic/plasmacytic perivascular cuffs, and a patchy increased prominence of cerebral blood vessels associated with hypertrophy of the vascular endothelium and/or thickening of their connective tissue walls. These lesions were associated with the presence of Toxoplasma gondii tissue cysts. Lesions in the eyes of both birds were bilateral and consisted of severe plasmacytic/granulomatous ophthalmitis. Surviving birds were treated with trimethoprim and sulfadiazine, no subsequent deaths occurred, and no new cases developed over an 8-month period.

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