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Biomedical subjects

M D Rickard

Publications and source records attributed to M D Rickard.

At least 73 records · Page 4Linked to original sources
PubMed1982

Antibody responses of experimentally infected lambs to antigens collected during in vitro maintenance of the adult, metacestode or oncosphere stages of Taenia hydatigena and Taenia ovis with further observations on anti-oncospheral antibodies.

The antigenicity and specificity of crude antigens collected during the in vitro maintenance of Taenia hydatigena and T. ovis, excretory/secretory (ES) antigens, were assessed in a peroxidase microenzyme-linked immunosorbent assay (ELISA), using sera from lambs given experimental monospecific infections with T. hydatigena, T. ovis, Echinococcus granulosus or Fasciola hepatica. ES antigens of larval cysts of T. ovis and T. hydatigena were less reactive than those of adult or oncosphere stages. Strong interspecific cros-reactions occurred between all antigen preparations, and these antigens offered no better specificity than crude somatic extracts. IgG1 was the major immunoglobulin detected in sera from lambs experimentally infected with T. ovis or T. hydatigena using antigens prepared from sonicated oncospheres. Discrete peaks of anti-oncospheral antibodies were detected following initial and challenge infections with eggs (whether the homologous or heterologous species), when sera were assayed with a PBS sonicate or an ES antigen from oncospheres. However, when oncospheres solubilised with sodium deoxycholate were used, the antibody response was prolonged and resembled that reported previously when somatic extracts of adult and metacestode stages were used as antigen. The results showed that oncospheres share antigens in common with other life-cycle stages, but also support the notion that they may possess some unique stage-specific antigenic determinants.

Animals↗
PubMed1981

Anti-oncospheral antibodies in the serum of lambs experimentally infected with either Taenia ovis or Taenia hydatigena.

Using a peroxidase micro-enzyme--linked--immunosorbent assay (ELISA) method anti-oncospheral antibodies were demonstrated in sera from four lambs after primary and challenge infections with Taenia ovis or T. hydatigena. Antibodies assayed using homologous oncospheral antigen (OA) reached a peak by 3-4 weeks after primary infection and at 1-3 weeks post-challenge infection, but waned to pre-infective, "background" levels by 8-12 weeks after each infection. Antibodies assayed against antigens in strobilar or cystic larval extracts persisted for long periods after the initial infections and exhibited different kinetics of response from those demonstrated against OA. These antibodies showed increased levels after challenge infection. Oncospheral antigens did not seem to be species specific although they appeared to elicit a stage-specific response. It is suggested that the anti-oncospheral antibody response could be associated with protective or "functional" antibody.

Animals↗
PubMed1981

Immunisation of mice against Taenia taeniaeformis using antigens prepared from T. pisiformis and T. hydatigena eggs or oncospheres.

Experiments were carried out to investigation the degree of immunity stimulated against Taenia taeniaeformis infection in mice by prior administration of eggs or ultrasonically disrupted oncospheres of T. pisiformis or T. hydatigena. Sonicated oncospheral antigens were given either orally or by subcutaneous injection in Freund's complete adjuvant, and eggs were given orally. Three inbred strains of mice with varying degrees of innate resistance to initial infection with T. taeniaeformis were used in the experiments. These were the moderately resistant BALB/c, moderately susceptible CBA/H, and highly susceptible C3H/He strains. It was found that BALB/c mice developed high levels of immunity when immunised with either T. pisiformis or T. hydatigena eggs, or with sonicated oncospheres administered orally or parenterally. CBA/H mice developed moderate immunity, and C3H/He mice generally did not develop a satisfactory level of resistance. the implication of these findings with respect to immunisation of outbred animals against natural infection with larval cestodes using antigen prepared from the oncospheres of heterologous parasite species is discussed.

Animals↗
PubMed1981

Murine hybridoma-derived antibodies in the processing of antigens for the immunodiagnosis of hydatid (Echinococcus granulosus) infection in sheep.

Mice experimentally infected with hydatid parasite Echinococcus granulosus (secondary echinococcosis), were used as spleen cell donors for hybridoma production. Two hybridomas were produced which secreted antibody with anti-E. granulosus cyst fluid (EgCF) activity. Radioimmunoassays comparing the binding of these hybridoma-derived antibodies to E. granulosus versus several other antigen preparations from sheep parasites showed that the antibodies had a high degree of specificity for the hydatid parasite. However, using a panel of clinically defined sheep sera in a competitive radio-immunoassay, the binding of the hybridoma-derived antibodies to EgCF was inhibited strongly by sera from sheep infected with the common parasites Fasciola hepatica and Taenia hydatigena. When the hybridoma-derived antibodies were conjugated to CNBr-activated Sepharose and the crude EgCF applied to the affinity column, the "run through' antigen preparation showed a significant increase in specificity for experimental E. granulosus infection. A useful means of applying the hybridoma technology in the development of new immunodiagnostic reagents may be to select those murine hybridomas which produce high-affinity, cross-reacting antibodies and to use these antibodies in the processing of homologous antigen by affinity chromatography.

Animals↗
PubMed1981

A preliminary field trial to evaluate the use of immunisation for the control of naturally acquired Taenia saginata infection in cattle.

The efficiency of immunisation of cattle with antigens collected during 14-day in vitro cultivation of Taenia saginata or T hydatigena oncospheres for the control of naturally acquired bovine cysticercosis was tested on a farm which uses sewage effluent to irrigate pasture. A total of 260 first-calf heifers of mixed breed were divided into four groups which were either sham-vaccinated or vaccinated with T saginata antigen at 49 to 124 days or 16 to 91 days before calving or vaccinated at 49 to 124 days prepartum with T hydatigena antigen. Ten calves from each group were killed at about three months of age and all muscles, including heart, tongue and oesophagus, were examined for cysticerci. Precalving vaccination with T saginata antigen significantly reduced the number of cysticerci found. Calves from sham-vaccinated cows were either sham-vaccinated or vaccinated with T saginata antigen or T hydatigena antigen at 46 to 121 days olds. Calves from cows immunised with T saginata antigen were either sham-vaccinated or immunised with T saginata antigen. Calves from cows injected with T hydatigena antigen were either sham-vaccinated, vaccinated once with T hydatigena antigen when 46 to 121 days of age or vaccinated twice with T hydatigena antigen at median ages of 65 days and 99 days. All these calves were killed at 13 to 14 months old and their heart, diaphragm, tongue and masticatory muscles examined for cysticerci. Of the 38 surviving sham-vaccinated calves from sham-vaccinated cows, 21 animals (55 per cent) were infected. Several of the vaccination regimes reduced this rate of infection significantly but the most effective was precalving vaccination of the cow and vaccination of the calf with T saginata antigen which reduced infection by 78 per cent compared with the controls. Precalving vaccination of cows with T hydatigena antigen together with double vaccination of their calves with the same antigen preparation also significantly reduced infection in the calves by 64 per cent.

Animals↗
PubMed1981

Immunisation of calves against Taenia saginata infection using antigens collected by in vitro incubation of T saginata oncospheres or ultrasonic disintegration of T saginata and T hydatigena oncospheres.

The intramuscular injection of calves with antigens (in oil adjuvant) collected during 14 day in vitro cultivation of Taenia saginata oncospheres and centrifuged at 500 g, stimulated a high level of resistance against challenge infection with eggs. When calves were immunised with antigens which had been collected during short-term (24 hour and 72 hour) in vitro incubation in culture medium and centrifuged at 3000 g, a significant but much less striking degree of immunity was produced. Calves immunised with a single injection (in oil adjuvant) of 30,000 T saginata oncospheres, disrupted by ultrasonic disintegration, also developed a high level of immunity to a subsequent challenge infection. A supernatant of the sonicated T saginata oncospheres centrifuged at 100,000 g stimulated a lesser degree of immunity. Sonicated T hydatigena oncospheres were less effective than T saginata oncospheres although they did stimulate a significant level of protection. The results suggest that prolonged periods of in vitro incubation of hatched and activated taeniid oncospheres are not necessary to collect antigens which will stimulate immunity to infection and that the antigens which stimulate protective immunity may initially be membrane associated or particulate in nature. Sonication produces only partial solubilisation of these antigens.

Animals↗
PubMed1980

Evaluation of "crude" antigen prepared from Taenia saginata for the serological diagnosis of T. saginata cysticercosis in cattle using the enzyme-linked immunosorbent assay (ELISA).

A "crude" antigen prepared from the strobilate stage of Taenia saginata was tested for its suitability in the peroxidase microenzyme-linked immunosorbent assay (ELISA) for the diagnosis of T. saginata cysticercosis in cattle. Sera were tested from laboratory and pasture-reared calves experimentally infected with T. saginata as well as from cattle naturally infected by grazing on pasture irrigated with sewage effluent. The specificity of the "diagnostic" antigen was assessed using sera from laboratory-reared cattle with monospecific infections of T. saginata, T. hydatigena, Fasiciola hepatica, or gastro-intestinal nematodes, and natural infections of F. hepatica. Cross-reactions occurred in sera from all heterologous infections but the highest level occurred in cattle experimentally or naturally infected with F. hepatica. Clear diagnostic antibody levels were found in cattle experimentally infected with T. saginata but the test was not found to be reliable in individual animals with natural infections when compared with sera from cattle naturally infected with . hepatica. On a group or herd basis ELISA using "crude" antigen and taking the mean absorbance values, could be useful as an indicator of a high prevalence rate of T. saginata cysticercosis.

Animals↗
PubMed1980

Hybridoma antibody immunoassays for the detection of parasitic infection: attempts to produce an immunodiagnostic reagent for a larval taeniid cestode infection.

Attempts have been made to produce discriminatory immunodiagnostic reagents for infections of sheep with the larval stages of Taenia hydatigena, Taenia ovis and Echinococcus granulosus. Using cells from mice hyperimmunized with T. hydatigena antigenic preparations for fusion, a hybridoma antibody which bound to T. hydatigena larval antigens, but not to T. ovis or E. granulosus larval antigens, was selected. A competitive radioimmunoassay using the labelled hybridoma antibody and a crude parasite antigen mixture was devised as an immunodiagnostic test for experimental T. hydatigena infection. Sera from sheep exposed to 1000 or more T. hydatigena eggs were unequivocally positive but sera from 2 sheep with a monospecific infection with T. ovis were also positive. Sera from E. granulosus-infected sheep were negative and, although the numbers of sera involved were small, such discrimination has not been achieved by previous serologic methods. The discussion emphasizes various difficulties which have been encountered in the development of highly sensitive as well as specific hybridoma-based immunodiagnostic reagents for the detection of larval cestode infections in sheep.

Animals↗
PubMed1980

A mechanism to account for mouse strain variation in resistance to the larval cestode, Taenia taeniaeformis.

Mice of various inbred strains differ markedly in resistance to first infection with Taenia taeniaeformis. Hypothymic nude mice of relatively resistant (e.g. BALB/c) and relatively susceptible (e.g. CBA/H) genotypes are highly susceptible but both can be protected against infection by injection of serum from infected mice. Using differential pH elution of "immune serum" from protein A-Sepharose, evidence was obtained that a combination of the pH 6 eluate (enriched for IgG1 molecules) plus the pH 3 or 4 eluate (enriched for IgG2 molecules) was more effective than either eluate alone at transferring protection to nude mice. By using whole serum transfer techniques, the rate of appearance of "host protective serum activity" (presumably antibody) was shown to be increased in genetically resistant versus susceptible mouse strains. It is suggested that, in relatively resistant mouse strains, host protective antibodies prejudice the establishment (or subsequent survival) of larvae prior to the full expression of protective mechanisms in the establishing larvae. In keeping with a host-protective effect of an accelerated immune response early in infection, a high dose challenge with eggs actually resulted in lower infection levels in genetically resistant mouse strains such as BALB/c and C57B1/6. The proposed mechanism of immunologically mediated, genetically based variation in susceptibility to T. taeniaeformis should not influence the effectiveness of a model vaccine against first infection in all strains of mice.

Animals↗
PubMed1979

Attempts to immunise rats and mice against infection with fasciola hepatica using antigens prepared from taenia hydatigena.

Attempts were made to immunise rats and mice against infection with F. hepatica by oral dosing with T. hydatigena eggs, or by vaccination with various T. hydatigena antigen preparations. These antigens included extracts from T. hydatigena cysticerci and cyst fluid, and antigens collected during short-term (48 h) and long-term (14 days) in vitro cultivation of larvae. Immunity was assessed by the numbers of F. hepatica recovered from the challenge infection in rats, and the mortality rates of infected mice. None of the immunisation regimes with T. hydatigena antigens induced consistent, significant immunity. This was in contrast to the high level of immunity shown by rats dosed orally with F. hepatica metacercariae four weeks prior to challenge infection.

Animals↗
PubMed1979

The serodiagnosis of human hydatid disease: 2. Additional studies on selected sera using indirect haemagglutination (IHA), enzyme linked immunosorbent assay (ELISA) and defined antigen substrate spheres (DASS).

Sixty-one serum samples selected on the basis of reactivity in the complement fixation (CF) and latex agglutination (LA) test, were further examined for sensitivity and specificity by indirect haemagglutination (IHA), enzyme linked immunosorbent assay (ELISA) and defined antigen substrate spheres (DASS). Twenty sera from healthy Europeans and 48 samples from patients with either schistosomiasis or trichinosis were also tested. Comparable levels of sensitivity were found between the CF and LA positive sera and IHA, ELISA and DASS. Of the CF positive LA negative group of sera, many were positive by DASS but only a few reacted in IHA and ELISA. Some cross reactivity was also observed in the schistosomiasis sera tested by IHA and ELISA.

Adult↗