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D Wakelin

Publications and source records attributed to D Wakelin.

At least 73 records · Page 4Linked to original sources
PubMed1995

Immunity to Trichinella spiralis transferred by serum from vaccinated mice not protected by immunization.

Serum antibody responses to infection with the intestinal helminth Trichinella spiralis in mice remain at low levels for the first ten to 12 days, slowly increasing to high titres around day 20. It is thought that antibody, therefore, has a limited role in the primary immune response raised against this infection and this is confirmed by the inability of primary infection serum to transfer immunity adoptively. High-responder NIH and low-responder B10 mice were vaccinated with T.spiralis antigen in Freund's complete adjuvant prior to challenge. This procedure conferred significant protection on NIH mice but not B10. Sera from these mice were transferred into recipients before and during challenge infection. Significant levels of protection were obtained in both strains with both homologous and heterologous sera, even though vaccination itself had not resulted in protection of the B10 donor mice. These data indicate that the B10 strain is potentially capable of making a protective immune response against the intestinal phase of T.spiralis.

Animals↗
PubMed1995

Efficacy of oral vaccination against the murine intestinal parasite Trichuris muris is dependent upon host genetics.

Oral vaccinations with Trichuris muris adult worm homogenate antigen with cholera toxin as the adjuvant were successful in both high-responder BALB/c and low-responder C57BL/10 mice, resulting in high levels of protection against subsequent infection, but were ineffective in the low-responder B10.BR mice. Subcutaneous vaccination with antigen in Freund's complete adjuvant resulted in protection of all of these strains but was most effective in high-responder BALB/c and least effective in B10.BR mice. Oral vaccination resulted in a T. muris-specific intestinal immunoglobulin A response only in the two protected strains. High levels of serum immunoglobulin G1 antibody were induced by Freund's complete adjuvant vaccination in all cases. A relationship between vaccine efficacy, expulsion phenotype, and induced T-helper subset-associated cytokines (interleukin-5 and gamma interferon) was noted. It was concluded that effective vaccination against T. muris requires the induction of Th2 responses and that this can be achieved by both oral and parenteral administration of antigens.

Administration, Oral↗
PubMed1995

Cytotoxic effects of natural killer cells have no significant role in controlling infection with the intracellular protozoon Eimeria vermiformis.

The course of infection with Eimeria vermiformis in C57BL/6J; NK cell-defective C57BL/6J bg/bg; BALB/c; T-cell-defective BALB/c nu/nu; and T-cell-, B-cell-, and NK cell-defective BALB/c x C57BL/6 scid/scid bg/bg mice was monitored. For young C57BL/6J mice, the bg/bg mutants consistently produced fewer oocysts than the controls; there were no differences between older mice of these strains. Wild-type BALB/c mice were more resistant to infection than the nu/nu and scid/scid bg/bg mutants, but there was no difference between the mutants. Treatment of BALB/c mice with poly(I.C) had no effect on the course of infection. These findings confirm the ineffectiveness of NK cells in this system.

Animals↗
PubMed1995

High levels of protection induced by a 40-mer synthetic peptide vaccine against the intestinal nematode parasite Trichinella spiralis.

Parenteral vaccination, using a 40-mer synthetic peptide from a 43,000 MW immunodominant glycoprotein secreted by the intestinal nematode parasite Trichinella spiralis, induced high levels of protection against a subsequent challenge infection in mice. The expulsion of adult worms from the gut was accelerated following vaccination with peptide 40-80, but peptides 81-120 and 121-160 were not protective. Mesenteric lymph node cells taken from T. spiralis-infected mice showed some proliferation in response to in vitro stimulation with peptide 40-80, but were unaffected by peptide 81-120. As expulsion of T. spiralis is known to be brought about by T-cell-mediated inflammatory events in the intestine, the ability of the 40-80 sequence to promote accelerated worm expulsion upon challenge infection may reflect induction of a specific and appropriate T-cell response. To our knowledge, this is the first report of a protective synthetic peptide vaccine against an intestinal nematode.

Amino Acid Sequence↗
PubMed1994

The major secreted product of the whipworm, Trichuris, is a pore-forming protein.

The data presented here describe the first unequivocable characterization of a pore-forming protein in any helminth parasite. The excretory/secretory (E/S) material of the human whipworm T. trichiura contains a highly abundant protein of molecular mass 47 kDa (TT47); the murine model parasite, T. muris, contains a similarly abundant protein of molecular mass 43 kDa (TM43). When purified to homogeneity, these proteins induce ion-conducting pores in lipid bilayers. Antibodies raised against TM43 abolish channel activity. Pore formation in epithelial cell membranes may facilitate invasion of the host gut by Trichuris and enable the parasite to maintain its syncytial environment in the caecal epithelium. The observation that this activity may be inhibited by antibody opens a possible avenue for drug and vaccine development.

Animals↗
PubMed1994

Induction of T lymphocyte subsets and levels of interleukin-2 and interleukin-3 after infection with Trichinella spiralis are similar in mice of high- and low-responder phenotypes.

Various aspects of T lymphocyte responses in mice with high- and low-responder phenotypes to infection with the nematode Trichinella spiralis were compared. Mesenteric lymph node cells (MLNC) from infected NIH strain mice (high-responder) showed a much higher level of proliferation in response to parasite antigen than MLNC from infected C57.B10 mice (low-responder). Levels of CD4+ and CD8+ T lymphocytes in the MLN remained relatively constant in both strains, ruling out the possibility that the more rapid worm expulsion in NIH mice (day 6 post-infection, as compared to day 12-15 in B10 mice) was due to quantitative differences in levels of CD4+ T helper cells. To examine any variation in the recruitment of Th1 v Th2 cell subsets, the production of the cytokines interleukins-2, -3, and -4 (IL-2, -3, and -4) by MLNC in response to parasite antigen was measured throughout the course of infection. Amounts of IL-2 and IL-3 were broadly similar in both strains, while almost background levels of IL-4 were detected. However, NIH strain mice produced IL-2 and IL-3 more rapidly than B10 mice. These data support the conclusion from other authors that the response to T. spiralis is not dependent on the absolute levels of cytokines produced, but rather on timing of production and rapidity of recruitment of effector cells at the level of bone marrow precursors.

Animals↗
PubMed1994

The response of hamsters to primary and secondary infection with Trichinella spiralis and to vaccination with parasite antigens.

The duration of primary infections with T. spiralis was dose-dependent with greater proportional loss of worms from heavily infected hamsters and longer persistence of worms in syngeneic DSN hamsters carrying initially low intensity infections. Intestinal worms were lost more rapidly from challenged immunized animals with over 80% loss of established worms by day 6 post infection, but survival of residual worms for a further 2 weeks. Hamsters carrying initially more than 140 intestinal worms began to lose weight during the second week indicating severe pathology at this stage of infection. Mucosal mast cell numbers increased from 50 cells/20 villus crypt units in uninfected animals to a peak in excess of 150 during week 4 pi, although intestinal mastocytosis persisted long after the loss of the majority of adult worms. Serum antibody responses to muscle stage larval antigen were detected in week 3 and increased subsequently. Both mastocytosis and antibody responses were more intense on secondary exposure to infection. Hamsters vaccinated with muscle stage larval antigen showed only a moderately accelerated loss of the intestinal phase but the fecundity of worms was severely suppressed. Overall it was concluded that the hamster host provided a model of trichinellosis that, in many respects was closer than mice and rats to the pattern of infection seen in economically and clinically important host species.

Analysis of Variance↗
PubMed1994

Effect of ivermectin on infection with gastro-intestinal nematodes in Sierra Leone.

Levels of intestinal nematode infections were assessed six months after a two year trial of ivermectin for efficacy against onchocerciasis had ended. In the trial the inhabitants of six villages in Sierra Leone were offered treatment with ivermectin or placebo at six monthly intervals for four rounds in total. Quantitative faecal egg counts were carried out on stool samples provided by 202 subjects, all of whom had received all four rounds of treatment, in two of the villages (Dodo and Mogibisi). These data were analysed by a novel procedure in which a 3-way ANOVA with negative binomial errors enabled village and host gender influences on the outcome of treatment to be identified. Necator americanus was the most common species showing an overall prevalence of 90% but a higher intensity in Mogibisi relative to Dodo, particularly among male subjects. Neither prevalence nor intensity of infection were altered in ivermectin-treated compared with placebo-treated subjects. Trichuris trichiura was the least common species with a prevalence of 15%. It was concluded that there was no significant protection from infection with this species among the ivermectin relative to the placebo-treated subjects. Ascaris lumbricoides, with an overall prevalence of 39%, was more common among female (50%) compared with male (27%) villagers. Prevalence was not significantly affected by ivermectin but the intensity of infection declined by 91.3% in Dodo whilst in Mogibisi intensity was only reduced by 14.6%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Interactions between infections with Eimeria spp. and Trichinella spiralis in inbred mice.

Parasitological and immunological interactions between Eimeria vermiformis or E. pragensis and Trichinella spiralis were investigated during concurrent infections in NIH, BALB/c and B10.G inbred mice. The establishment of T. spiralis was unaffected by the presence of either coccidium, but expulsion of adult worms was delayed significantly in mice infected with E. vermiformis; E. pragensis did not have this effect. Replication of E. vermiformis was enhanced in concurrent infections with T. spiralis, but that of E. pragensis was reduced. Specific immune responses to each parasite were unaffected in mice infected with T. spiralis and E. pragensis, but levels of some responses were reduced when T. spiralis and E. vermiformis were combined. Thus both in vitro antigen-induced proliferation of mesenteric lymph node cells (MLNC) and intestinal mastocytosis were lower than in singly infected mice. Mitogen (Con A) responsiveness of MLNC was not affected in mice infected with T. spiralis and E. vermiformis, and cells from these mice were capable of transferring protective immunity to the nematode in naive recipients. Injection of monoclonal antibody to interferon gamma, a major component of the cytokine response to E. vermiformis, did not prevent delay of worm expulsion in concurrent infections. The results are discussed in terms of possible interactions between the T helper cell subsets or the inflammatory components of the responses induced by each parasite.

Animals↗
PubMed1994

The role of natural killer cells in resistance to coccidiosis: investigations in a murine model.

Natural killer (NK) activity, detected by the lysis of Yac-1 target cells, was examined in splenic and mesenteric lymph node (MLN) cells throughout the course of infection with Eimeria vermiformis in BALB/c and C57B1/6 (B6) mice. These strains are, respectively, relatively resistant and susceptible to primary infections, which render them equally, and completely, resistant to challenge. Resting levels of NK activity were higher in B6 than in BALB/c, and B6 responded earlier in the course of infection than BALB/c, but splenic peak values were higher in BALB/c; the pattern of response in MLN cells was similar in both strains, but the peak was higher in BALB/c. At the time (7 days p.i.) of peak NK response in BALB/c mice there was, depending upon the choice of NK-resistant/lymphokine-activated killer (LAK)-sensitive target cells, either little (P388D1), or no (P815) splenic LAK activity. Challenge of immunized BALB/c mice did not evoke a detectable NK response. Although the higher NK activity in BALB/c mice correlated with greater control of primary infection, depletion of NK activity (demonstrated in splenic cells) in vivo by treatment with anti-asialo GM1 antibodies did not greatly affect the course of infection. Furthermore, this treatment did not augment the exacerbation of infection produced by treatment with anti-interferon-gamma (IFN-gamma) MoAb, indicating that, at least in this system, NK cells are not a fundamentally important source of this controlling cytokine of eimerian infections. The results suggest that NK cells may not greatly influence the outcome of coccidial infections.

Animals↗
PubMed1994

Lymphocyte proliferation and cytokine production in mice infected with different geographical isolates of Trichinella spiralis.

Antigen-specific proliferative responses and cytokine production were measured in lymphocytes taken from inbred NIH mice infected with different isolates of Trichinella spiralis. Stimulation with muscle larval homogenate antigen produced high proliferative responses, cells responding more strongly to antigen from one isolate (London-L) than to antigens of the other two isolates (Spanish-S and Polish-P). Antigen from the P-isolate elicited relatively poor responses. There was considerable, although variable, cross reactivity between isolate antigens and this was reflected in proliferation to heterologous stimulation. When pulsed with the mitogen Concanavalin A (Con-A) mesenteric lymph node cells (MLNC) produced IFN-gamma on day four post infection but not on day eight. In contrast, production of IL-4 and IL-5 was greatest on day eight. Differences were seen in levels of cytokine production between cells taken from mice infected with different isolates. These data show a sequential activation of Th1 and Th2 cells during infection with T. spiralis isolates, and suggest that the level of activation of each Th subset is influenced by the antigenic characteristics of each isolate.

Animals↗
PubMed1994

Lymphocyte, antibody and cytokine responses during concurrent infections between helminths that selectively promote T-helper-1 or T-helper-2 activity.

The influence of Trichinella spiralis on infections with Trichuris muris was studied in non-responder B10.BR mice. Mice infected only with T. muris were unable to expel parasites and had many adult worms 35 days later. Infection with 300 larvae of T. spiralis, given seven or 14 (but not 28) days after T. muris, enabled mice to expel up to 90% of T. muris; expulsion of T. spiralis was not altered. Concurrently infected mice produced less T. muris-specific IgG2a antibody than mice infected with T. muris only, and showed higher proliferative responses when spleen and mesenteric lymph node cells were cultured in vitro with T. muris antigens. When T. spiralis was present mucosal mast cells were generated in T. muris-infected mice, whereas almost no mast cells were seen with only T. muris. Lymphocytes from doubly-infected mice produced significantly more interleukin 4 and 5 (IL-4, IL-5) and significantly less interferon-gamma (IFN-gamma) when stimulated in vitro with Concanavalin A (Con-A) than cells from mice infected with T. muris only. These data demonstrate that B10.BR mice, which in single infections produce a Th1 response to T. muris and develop no protective immunity, can mount a protective T-helper-2 (Th2) response and expel T. muris when concurrently infected with the 'Th2-inducing' nematode T. spiralis.

Animals↗
PubMed1994

Effect of genetic variation on induced neutrophilia in mice.

Mice from a variety of strains were injected with a sterile irritant (Brewer's thioglycolate) and killed bacteria (Staphylococcus aureus, Staphylococcus epidermidis, or Escherichia coli) to determine their effect on accumulation of neutrophils in the peritoneal cavity. Peak accumulation occurred around 15 h postinjection and showed significant strain-related variation. C57BL/10 mice were identified as having a high-responder phenotype and BALB/c mice a low-responder phenotype. Inheritance of the high-responder phenotype followed simple Mendelian genetics: (BALB/c x C57BL/10)F1 mice were found to be more responsive than either parental phenotype. Major histocompatibility complex H-2d haplotype was found to convey an augmented neutrophil response in conjunction with B10 background high-responder genes (B10.D2/n) but the H-2d haplotype per se was not the only factor in determining high responsiveness. Gram-positive and gram-negative bacteria appeared to activate different immune mechanisms. Both gram-negative bacteria and lipopolysaccharides (LPS) induced a response similar to, but less potent than, that induced by Brewer's thioglycollate. Neutralization of the LPS content of Brewer's thioglycolate abrogated the response.

Animals↗
PubMed1994

Immunization against experimental coccidiosis produces contrasting results in inbred mice of differing susceptibility to infection.

Pretreatment of inbred mice with intravenous and/or intraperitoneal injection of an antigen prepared from sporozoites of Eimeria vermiformis modulated the course of infection with the parasite in a manner that depended on the resistance-susceptibility phenotype of the host. Mice with a resistant background (BALB) produced more oocysts and those with a susceptible background (C57BL) produced fewer oocysts than their respective controls. The optimum conditions for producing these effects were established, and evidence is presented which suggests that the phenomenon might also apply in the target host, the chicken.

Animals↗
PubMed1994

Vaccination against the nematode Trichinella spiralis in high- and low-responder mice. Effects of different adjuvants upon protective immunity and immune responsiveness.

Groups of NIH and C57BL/10 (B10) mice were vaccinated subcutaneously with excretory/secretory material from the nematode parasite Trichinella spiralis using a variety of different adjuvants, i.e. complete Freund's adjuvant (CFA), 'TiterMax', alum and ISCOMs. ISCOMs were also given orally. NIH mice, known to be rapid responders to T. spiralis, expelled their worms earlier than usual with vaccination. The slow-responder B10 mice did not expel worms any earlier, no matter which adjuvant was used. The antibody isotype response profiles following vaccination with the four adjuvants did not differ significantly; however NIH mice generally produced higher levels of antibody than B10 and CFA induced the highest overall response. NIH cells yielded stimulation indices far in excess of the B10 following in vitro stimulation with T. spiralis antigen. Secretion of interleukin-5 (IL-5) and interferon-gamma (IFN-gamma) by these cells followed similar trends, i.e. higher levels from NIH than B10. A high IL-5 level in the NIH strain was accompanied by low-level IFN-gamma production following infection, whereas the IFN-gamma response was not observed in B10 supernatants. This study shows that vaccination using these adjuvants did not appear to modify the immune response qualitatively, but the magnitude of the response was affected greatly.

Adjuvants, Immunologic↗
PubMed1994

Immune responses to Trichinella spiralis and T. pseudospiralis in mice.

A comparison was made of the immunological responses of inbred NIH mice to the intestinal stage of infection with two species of the genus Trichinella, T. spiralis and T. pseudospiralis, which are known to have distinct parasitological and pathological relationships with their hosts. The parameters studied, namely antigen-specific IgG1 and IgG2a antibody responses, mucosal mastocytosis, and levels of the cytokines interferon-gamma (IFN-gamma) and interleukin-5 (IL-5) produced by concanavalin A-pulsed mesenteric node lymphocytes in vitro, were chosen to provide information about the relative activities of the Th1 and Th2 T-helper (Th) lymphocyte subsets. In this high-responder host the time-course of infections was similar, although initial levels of establishment were considerably higher for T. pseudospiralis. Both species elicited mucosal mastocytosis. Distinct differences were seen in the IgG isotype responses. Trichinella spiralis-infected mice produced a predominantly IgG2a response, whereas T. pseudospiralis elicited an IgG1 response. Cytokine release showed infection dose-related suppression of IFN-gamma and enhancement of IL-5. These effects were most marked in T. pseudospiralis-infected mice, i.e. there was an earlier shut-off of IFN-gamma and an earlier switch to IL-5. These data suggest that the two species of Trichinella show a time-related differential activity of Th subsets during the early stages of infection. The possibility that this may reflect antigenic differences between these closely related species or result from parasite-induced immunological-endocrinological changes is discussed.

Animals↗
PubMed1993

MHC haplotype influences primary Giardia muris infections in H-2 congenic strains of mice.

The course of primary Giarda muris infections was studied in H-2 congenic strains of mice on the BALB and C57BL/10 (B10) genetic backgrounds. Infection was curtailed more rapidly in B10 strains, compared with BALB strains, and unaffected by H-2 haplotype. On the other hand the duration of infection in BALB strains did vary with H-2 haplotype with BALB/B(H-2b) mice taking significantly longer to clear infection than BALB/c(H-2d) and BALB/K(H-2k) mice. These experiments demonstrate that both MHC and non-MHC genes influence the outcome of primary G.muris infections.

Animals↗