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Biomedical subjects

C Dobson

Publications and source records attributed to C Dobson.

At least 73 records · Page 4Linked to original sources
PubMed1984

Infections with Salmonella typhimurium and Nippostrongylus brasiliensis in mice selectively reared for high or low immune responsiveness to Nematospiroides dubius.

Mice which had been selectively reared over six generations for high (H) and low (L) immune responsiveness to N. dubius (Sitepu and Dobson, 1982) were infected with Salmonella typhimurium and N. brasiliensis to examine the specificity of the selection process for heterologous infections. H mice were marginally more susceptible than L mice to S. typhimurium, whereas H mice were more resistant to infection with N. brasiliensis than L mice. Both H and L mice were protected against N. dubius following immunization with N. brasiliensis larvae.

Animals↗
PubMed1983

Host specificity in mice selected for innate immunity to Nematospiroides dubius: infections with Nippostrongylus brasiliensis, Mesocestoides corti and Salmonella typhimurium.

The selection of mice for innate immunity to Nematospiroides dubius was not specific. Mice bred as refractory (R) to N. dubius infection were more refractory to primary infections with Nippostrongylus brasiliensis than other mice bred as liable (L) to infection with N. dubius. R and L, as well as randomly-bred (Rd) and inbred C3H mice were all immune to challenge infection with N. brasiliensis. Previous infections with N. brasiliensis failed to influence the course of N. dubius infections or the status of the selected mice as R, Rd and L to infection with N. dubius. R and L mice were equally susceptible to Mesocestoides corti infection but more resistant than Rd mice. R and L mice died sooner after infection with Salmonella typhimurium than Rd, although R survived longer than L mice.

Animals↗
PubMed1983

Immunological regulation of Angiostrongylus cantonensis infections in rats: modulation of population density and enhanced parasite growth following one or two superimposed infections.

Rats acquired a degree of protective immunity to reinfection with Angiostrongylus cantonensis after a single infection with 50 infective larvae. Infected rats resisted the establishment of most challenging larvae and protective immunity increased with subsequent reinfections. Part of the primary infection was lost after a superimposed second and also following a superimposed third infection, but the total size of the concurrent adult worm populations remained the same as that from a primary infection. Worms surviving from the primary infection showed enhanced growth after each reinfection but their fecundity was impaired.

Angiostrongylus↗
PubMed1983

Genetic control of liability to infection with Nematospiroides dubius in mice: direct and correlated responses to selection of mice for faecal parasite egg count.

Mice selected as liable (L) and refractory (R) over 10 generations voided significantly more and less Nematospiroides dubius eggs compared with randomly mated (Rd) mice after primary infection with 100 larvae. Strong positive correlation was found between the numbers of N. dubius eggs in mouse faeces and the numbers of adult N. dubius recovered from mice culled from the R, Rd and L colonies. Selection limit based on a faecal e.p.g. was reached in the L mice after 9 generations whereas the faecal N. dubius e.p.g. voided by the R mice continued to decline throughout selection. In contrast, no change in worm numbers was found in L or R mice after 6 generations. The refractory state of the trait, liability to infection with N. dubius, was inherited as a dominant character with a realized heritability value of approximately 0.2. Differential correlated responses from N. dubius infectivity compared with N. dubius fecundity and growth indicated murine genetic control of this trait by 2 major genetic units. In general, there were negative phenotypic and genetic correlations between the faecal N. dubius e.p.g. of mice and murine morphological conformation, but positive correlations between the faecal N. dubius e.p.g. of selected mice and establishment, growth and fecundity of N. dubius populations in these mice. There was little correlation between the faecal N. dubius e.p.g. after primary infection and anti-N. dubius antibody titres and parasite female/male sex-ratio.

Animals↗
PubMed1983

Specificity of passive serum protection against Nippostrongylus brasiliensis and Nematospiroides dubius in mice.

Fewer and smaller worms were recovered from, and significantly fewer parasite eggs were voided by, mice injected with mouse antiserum raised against Nippostrongylus brasiliensis or Nematospiroides dubius after infection with the homologous nematode species compared with the control mice. The passive transfer of protective immunity was specific for the species which induced the antibody response in the donor mice. Passively immunized mice infected with the heterologous nematode species harboured the same number of worms, with the same epg output, as parasites in the control mice, but were stunted. Serological cross-reactions were observed between the two donor antiserum pools and N. dubius and N. brasiliensis antigens.

Animals↗
PubMed1982

Passive immunity in rats infected with Angiostrongylus cantonensis: interactions between syngeneic immune serum and sensitized lymph node cells.

Immune serum injected into the peritoneum of rats passively protected them against Angiostrongylus cantonensis; this protection was greater than that conferred by passively transferred immune lymph node cells. When immune lymph node cells and serum were transferred together into the same rat, no enhanced protection was observed. The protective effect of serum was inhibited by the lymph node cells to levels commensurate with those conferred by immune lymph node cells alone. Normal lymph node cells also depressed the levels of immunity conferred by immune serum when they were transferred together with serum, but to a lesser extent than did sensitized lymph node cells. Transferred antibody acted to suppress antibody production against A. cantonensis in recipient rats.

Angiostrongylus↗
PubMed1982

Antibody responses in rats infected with Angiostrongylus cantonensis and the passive transfer of protective immunity with immune serum.

Little haemagglutinating antibody was detected in the serum of rats with primary Angiostrongylus cantonensis infections until the juvenile worms left the brain and lodged in the lungs about 35 days after infection. Antibody titres reached a peak 50 days after infection and were maintained for at least a further 95 days. Increasing the infective dose of A. cantonensis larvae increased the peak antibody titres attained by the infected rats. Re-infection temporarily reduced the serum antibody titre, but later it increased and showed an anamnestic response. Reaginic antibody production was transient during primary infections; re-infection failed to stimulate further reaginic antibody production. Antiserum from immune donor rats protected recipients against A. cantonensis. The transferred immune serum suppressed anti-A. cantonensis antibody production in recipient rats.

Angiostrongylus↗
PubMed1982

Genetic control of resistance to infection with Nematospiroides dubius in mice: selection of high and low immune responder populations of mice.

F1, Quackenbush (Q) x Wild (W) Mus musculus were assayed and selected for their level of immunity to secondary infections with 100 Nematospiroides dubius using faecal parasite egg counts. A significant positive linear correlation was found between the number of parasite eggs voided in the faeces and the number of N. dubius recovered after secondary infections in mice. Selection for immunity was not influenced by the conformation of the mice. High (H) and low (L) responder colonies together with a randomly (Rd) bred colony of mice were established over 5 generations. Adaptive immunity was more efficacious in protecting female than male mice and appeared to be controlled by a few dominant genes; the heritability (h2) of the trait was estimated at 0.56 for the parental stock and 0.55 for the F5 Rd colony and the realized heritability was 0.49. Higher anti-N. dubius antibody titres were detected in H than L mice. H mice harboured fewer and less fecund parasites than Rd colony mice; L mice had more worms with greater fecundities than Rd mice. The levels of primary infections in H and L mice related to the levels developed after secondary infection from F4. This suggested at least partial linkage of genes controlling innate with genes controlling adaptive immunity against N. dubius.

Animals↗
PubMed1982

Population dynamics of Angiostrongylus cantonensis during primary infections in rats.

About 35% of Angiostrongylus cantonensis larvae became patent adults irrespective of the dose used to establish primary infections in laboratory rats. Worm growth and fecundity was depressed in infections from high compared with low doses of infective larvae. Rats infected with up to 50 A. cantonensis larvae survived infection better than rats given greater numbers of larvae. The biology of A. cantonensis surviving in laboratory rats from single infections with 50 larvae for over a year was studied. Stable worm numbers and fecundity were established 90 days after infection but the worms continued to grow until the experiment was terminated.

Angiostrongylus↗
PubMed1982

Multiple infections with Nematospiroides dubius in mice selected for liability to a single infection.

The faecal egg counts and worm burdens of mice selected over 7 generations as refractory (R), random (Rd) or liable (L) to primary infection with Nematospiroides dubius were significantly different, but the antibody titres (generation 8 mice) after 21 days infection were similar, demonstrating that selection had separated populations of mice which differed in their innate immunity. Variations in adaptive immunity were also shown between the three colonies in terms of protection after challenge infections, self-cure reactions, humoral antibody titres and ability of immune serum from R, Rd and L donors to passively protect recipient Quackenbush (Q) strain mice. R mice were more refractory to primary infection and more proficient in acquiring protective levels of adaptive immunity than L colony mice. Correlation of the faecal parasite egg count after primary with that after secondary infection supported the conclusion that the genetic control of liability to primary infection and of the adaptive immune response following challenge infections were at least partially linked.

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