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Title: Studies on acquired immunity to Taenia taeniaeformis in rodents
Author: Sani, Rehana Abdullah
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1983
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This work is a study of both active and passively acquired immunity to Taenia taeniaeformis infection. The role of humoral components in serum as demonstrated by passive transfer of immunity and both active immunity following infection or immunisation were investigated. The antigens derived from larval T. taeniaeformis for immunisation studies were also used to raise immune sera, to monitor experimental infections, and to absorb out protective antibodies. Netacestodes retrieved from mice were maintained in a defined medium for between 10 and 23 days. The tegumental integrity of the metacestodes during maintenance was assessed by dye uptake and transmission electron microscopy (TENT). The medium in which the larvae had been held was used as a source of excretory-secretory antigen (ESA). Somatic antigen (SA) was derived from a saline extract of homogenised larval somata. Anti sera raised against both ESA or SA preparations, were used to detect antigens in the used medium by the enzyme linked immunosorbent assay (ELISA). After verifying that the ELISA technique could quantitate antigens, and that the assay was not affected by the presence of serum in the medium, the effect-of several factors on antigenic activity was investigated. The antigenic activity of the used medium did not appear to be unduly affected by the age of the larvae, by sealing the maintenance vessels, by variations in the integrity of the larval tegument or by the absence or presence of serum during maintenance. However, the beneficial effect of including serum in the maintenance was reflected in the dye uptake and MM results. The aim of studying these factors was to determine the optimal conditions under which the larvae would release 7nax4ma1 amounts of ESA. ELISA was also used to monitor the humoral response of mice and rats experimentally infected with TT taeniaeformis against either ESA or SA as the detecting antigens in the assay. It was found that ESA was a more sensitive indicator of the infection than SA. The ability of ESA and SA to protect rats against infection was investigated. Both these crude antigenic complexes seemed to possess similar immunising capacities. An association was found between the reactivity of these antigens in vitro by ELISA and their immunising or protective activity in vivo, which suggests that such antigens may provide a useful measure of the levels of protective antibody in the serum of the host. Homologous and heterologous immune sera were obtained by immunising rats and sheep respectively with ESA or SA. The immune sera obtained in this manner was protective in passive transfer experiments. This appears to be the first time that serum from animals immunised with ESA has been demonstrated to confer protection against a helminth infection. Immune serum from experimental infections of six weeks duration conferred almost absolute protection, confirming previous published reports. The highly protective immune globulins from active infections was absorbed with ESA, SA or live larvae. The absorption had a measure of success when assessed by in vitro estimation. However, when used in passive transfer, the absorbed globulins retained their protective ability. Several possible reasons were adduced for this apparent failure. Thus there may have been insufficient concentration of antigen to remove all the protective antibodies from the highly active serum. Alternatively the protective antibodies produced in an active infection may not be induced exclusively by the soluble components in ESA or SA, but possibly by both of these and even other antigens. Either of these suppositions would account for the partial efficacy of absorption found in vitro.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available