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1.
Primary and secondary infections of Hymenolepis citelli were followed in CFHB rats. In primary infections of 6, 20, and 50 cysticercoids, over 75% of the worms administered became established and grew. Thereafter, survival depended on the intensity of the primary infection. Acquired resistance to homologous challenge infections could be stimulated in rats by prior infection with H. citelli. The growth of secondary worms decreased as the intensity of the sensitizing infection increased. The protective response waned with time in the absence of the primary worms. Cross-protective responses between H. citelli and H. diminuta occur in rats infected previously with either parasite. Retardation in the growth of secondary worms may have an immunological basis.  相似文献   

2.
When mice were treated with 1.25 mg cortisone acetate thrice weekly, recovery of Hymenolepis muris-sylvaticae was significantly higher than in untreated controls, both in oral infections with six cysticercoids and surgical transplantations of one 7-day or 8-day-old worm. Cortisone treatment also resulted in the worms being located more anteriorly in the small intestine. Evidence of an immunological response against the tapeworm in the intestine is given by: an accelerated rejection of a secondary oral cysticercoid infection and a significant difference of the dry weights of the worms recovered on day 10 in CFLP mice; an accelerated rejection of a secondary surgical infection on days 4 and 6 in CFLP mice and on days 3 and 4 in NMRI mice; an accelerated rejection of a secondary surgical infection given 3 and 6 months after the primary immunizing infection in SWISS-albino mice.  相似文献   

3.
Hopkins C. A. and Barr I. F. 1982. The source of antigen in an adult tapeworm. International Journal for Parasitology12: 327–333. Although a primary infection of Hymenolepis diminuta is not rejected for 9–15 days by a mouse, it has been shown that a primary infection terminated chemically after only 3 days induces as good protection against challenge. This demonstrated that a scolex and 1–2 mm of neck tissue (all that is formed by day 3 post infection) are an adequate source of ‘protective’ antigen. Irradiated (350 Gy) cysticercoids which survive but show little growth immunize as effectively as normal cysticercoids which indicates actively growing neck tissue is not essential and hence the scolex alone is a sufficient source of ‘protective’ antigens. In the rat irradiated cysticercoids were found to establish, double their length over 3–6 days and then slowly shrink, but 14% of the worms were still present 49 days p.i. Although a primary infection of normal worms in a rat markedly depresses growth of a secondary infection administered 7 days after the chemical expulsion of the primary, irradiated scoleces induced no measurable protection. These results are discussed in relation to the source of antigen and the fundamental difference in the protective response of mice (an abnormal host) and rats (a normal host) to the tapeworm H. diminuta in the small intestine.  相似文献   

4.
Mice were infected orally with 1,6, or 30 cysticercoids of Hymenolepis diminuta. These were allowed to develop for different periods of time before elimination with anthelminthic, thus exposing the hosts to antigens from the prestrobilate, early strobilate, or fully strobilate worms. Other groups of mice were immunized by intraperitoneal (ip) implantation of a live strobilate worm or by ip implantation of live worms from cysticercoids excysted in vitro. Strong protection against challenge with a surgically transplanted strobilate worm was achieved by prior infection with 6 or 30 worms eliminated as early as Day 3 of infection. By this time these worms would not have strobilated. Conversely, a single worm, strobilating extensively over 16 days, stimulated only weak protection. Parenteral implantation of excysted worms protected mice but parenteral implantation of a strobilate worm had no effect. It is suggested that (i) the tapeworm protective antigens are primarily related to the scolex and/or the germinative region; (ii) the number of worms and the duration of antigenic stimulation in an immunizing infection determine the magnitude of a protective secondary response.  相似文献   

5.
A D Befus 《Parasitology》1975,71(1):61-75
In one (1 c) and six (6 c) cysticercoid primary infections of Hymenolepis diminuta in NIH (inbred) and CFLP (outbred) male mice 6 +/- 1 weeks old greater than 85% of the worms established but were rejected (destrobilated or expelled) subsequently. Rejection occurs more quickly in 6 c infections than in 1 c infections. Considerable worm growth occurs in 1 c and 6 c primary infections but worms from 6 c infections weighed less than worms from 1 c infections on all days studied. Expulsion of H. diminuta does not occur more rapidly in secondary infections than in primary infections; loss of 6 c secondary worms occurs at the same rate as 6 c primary worms but 1 c secondary worms survive longer than 1 c primary worms. Although worms are not lost more quickly in secondary than in primary infections, they are affected at an early age by the immune response which stunts their growth. Increasing the intensity of primary and secondary infections increases the severity of stunting of secondary worms. The results are discussed and it is suggested that immune responses to Hymenolepis spp. in rodents are common but that thresholds of worm numbers exist below which appreciable worm loss does not occur. Stunting due to crowding, which generally is attributed to inter-worm competition, may be in part immunologically mediated. For future immunological studies attempting to induce secondary responses to H. diminuta in mice, worm growth, not survival, is the criterion to evaluate.  相似文献   

6.
Opaque or darkened areas (DA) of variable size and position occur on Hymenolepis diminuta in mice and rats. In mice DA normally first appear in the neck region of the worm but subsequently they appear elsewhere and increase in number until destrobilation or worm expulsion. The posterior of destrobilated worms is often darkened. In the more immunogenic infections with six cysticercoids there are more DA per worm than in infections with one cysticercoid. DA are areas of the tegument with a homogeneous increase in electron density; abnormal mitochondria; reduced granular endoplasmic reticulum, Golgi complexes and discoidal secretory bodies; and accumulation of lipid droplets. DA disappear from worms maintained for up to 4 h in Hanks' balanced salt solution and can be induced by mechanical damage to the worms. As the numbers of DA increase with the duration and intensity of infection and have similarities with types of cell injury, they are probably sites of worm pathology induced by host immunity.  相似文献   

7.
A complete or almost complete resistance (94-100%) to a superimposed Echinostoma revolutum infection existed in mice harboring 20-, 30-, and 40-day-old infections in the range of 2-4 to 30-35 worms, but no resistance was found at challenge Day 10. A similar high level of resistance (85-100%) also existed in mice for at least 6 weeks after natural expulsion of a primary 6 metacercarial infection and for at least 5 weeks after anthelmintic termination of a 30-day-old 20 metacercarial infection. Thymus-deficient nude mice failed to develop resistance to a superimposed infection, and the resistance in normal mice was inhibited by corticosteroid treatment. These findings are all in favor of a host immune response being responsible for the resistance against both a secondary and a superimposed infection. Nearly all the worms of a superimposed infection were, in resistant mice, expelled prior to 24 hr following infection (rapid expulsion), and the few worms circumventing this early expulsion persisted for at least 8 days. Newly excysted juvenile worms implanted intraduodenally into resistant mice were rejected to the same degree as juvenile worms from an oral metacercarial infection indicating that the newly excysted juvenile worms are the target of the host immune response. However, 7-day-old worms implanted intraduodenally into resistant mice survived indicating that adaptation to the host immune response had occurred. In conclusion, this host-parasite model is an example of concomitant immunity because the immunological mechanism responsible for the expulsion of the superimposed infection had no effect on the number of primary worms present.  相似文献   

8.
Hamsters were given primary infections of 100, 200, and 300 D. viteae larvae and groups killed at various intervals after infection. In addition, hamsters were sequentially infected with 100, 200, and 300 larvae and groups killed at 100 or 75 days after the secondary and tertiary infection, respectively. Blood microfilariae were detected on Day 60 following a primary infection, reached a maximum on Day 75, declined to low levels by Day 105, and were negative on Day 120. No microfilariae reappeared in the blood of hamsters given secondary or tertiary infections.Between 20–30% of the infecting larval dose had reached the adult stage by Days 75 or 100 postinfection in hamsters given primary, secondary, or tertiary infections. There was no evidence of arrested larval development in hamsters receiving a second or third challenge infection. Almost half of the tertiary infection hamsters developed subcutaneous nodules and their numbers varied greatly among individual animals. The nodules variously contained living worms, pus, and fragmented worms, or pus only. Hamsters given primary infections of 100, 200, or 300 larvae and killed 375 days after infection had no subcutaneous nodules; however, hamsters given the 200 and 300 larval infections were seen to have dead worms in the subcutaneous tissues. No stunting of adult worms was noted and all female worms had uteri packed with microfilariae.  相似文献   

9.
Ultrastructural studies, including stereological analyses of micrographs, have been made of five-worm primary infections of Hymenolepis diminuta from C57 mice to determine whether the immune destrobilation/rejection process was accompanied by significant changes in the fine structure of the scolex tegument. Destrobilation/rejection of worms occurred from Days 9-12 after infection. For the first 5 days after infection, the scolex tegument showed no detectable differences in ultrastructure compared with that of "control" worms from either Wistar rats or immunosuppressed C57 mice. By Day 6, large lipid deposits were observed in the tegument and associated musculature of worms from untreated C57 mice. Further, worms recovered from Days 6-8 after infection also showed increased activity of the Golgi apparatus, GER, and mitochondria of the tegument, resulting in increased numbers of discoidal secretory bodies. Concomitant with destrobilation/rejection from Day 9 was a drop in the number of secretory bodies, an increase in autophagic activity throughout the tegument, and a blistering of the tegument surface plasma membrane. The possible functional significance of the results is discussed in relation to host immunity.  相似文献   

10.
Murine mast cells (MC) responded strongly to Hymenolepis microstoma infection. Starting day 7 postinfection (PI) and continuing until the end of the experiment (35 days PI), significantly larger numbers of MC were present in both the duodenum and bile duct of infected mice than in uninfected controls. In animals challenged with 5 cysticercoids 2 wk after primary infection, the MC response in the duodenum, but not in the bile duct, was of even greater degree than in naive hosts. The majority of MC in the duodenum of infected and challenged mice were intraepithelial mucosal MC, whereas in the bile duct the majority were connective tissue MC. Hypertrophy of the duodenal submucosa and of the bile duct wall was noticeable in all infected and challenged hosts. Worms in primary infections were not affected by the host response, but none of the worms in the challenge dose became established. It is postulated that the type of MC involved in specific immune response of the host is the intraepithelial MC, whereas the cell type participating in general inflammatory events is the connective tissue MC.  相似文献   

11.
Correlation between protective antibody response and patent infection with Hymenolepis nana in mice. International Journal for Parasitology16: 197–203. Mice inoculated with mouse-derived cysticercoids of Hymenolepis nana, as well as with eggs, produced IgG and IgE antibodies that were detected by double diffusion (DD) and passive cutaneous anaphylaxis (PCA), respectively. When mice inoculated with eggs (day 0) were challenged with eggs (day 66), all were resistant to the challenge (assessed by the failure of cysticercoid recovery in the intestinal tissue) and produced protective antibodies evidenced by passive transfer, as well as IgG and IgE isotypes. When mice inoculated with eggs (day 0) were treated with a highly efficacious cestocide, praziquantel on day 6 at the beginning of the lumen phase, all were also resistant to the egg challenge on day 66, however, IgE, IgG, and protective antibodies were not detected. When mice treated with praziquantel before patent infection were repeatedly challenged with high doses of eggs, some of them produced IgG and IgE antibodies. From these results, it is suggested that (1) the production of protective antibody is a secondary response after patency (which may be ascribed to eggs released from mature worms), and (2) mice initially given eggs are highly resistant to egg challenge showing that an effector mechanism of acquired resistance to egg challenge may be expressed without high titres of protective antibody, at least in the serum.  相似文献   

12.
The innate resistance of the unnatural rat host to the mouse tapeworm Hymenolepis nana is cortisone sensitive but thymus independent. When congenitally athymic nude rats were orally given eggs, cysticercoids, or adult worms of H. nana, no lumenal adults were established except when they were treated with cortisone acetate during the expected lumenal development. The effect of cortisone to promote adult maturation in the rats was compared in nude and normal rats given eggs of H. nana. The fecundity of the worms (assessed by the fresh worm biomass and the number of infective eggs produced) was much higher in cortisone-treated nude rats than in cortisone-treated normal rats. When the nude rats reconstituted with thymocytes were given eggs and treated with cortisone, the fecundity of H. nana dropped to the same level as in cortisone-treated normal rats. It is strongly suggested that the unnatural rat host has thymus-independent cortisone sensitive resistance to an initial infection (which is the main component of the innate resistance and blocks the lumenal establishment of this parasite) and thymus-dependent resistance (which suppresses the established worms' fecundity and may be ascribed to acquired resistance to the ongoing infection).  相似文献   

13.
, and 1988. Lumen phase specific cross immunity between Hymenolepis microstoma and H. nana in mice. International Journal for Parasitology 18: 1019–1027. When mice inoculated with five cysticercoids of Hymenolepis microstoma were challenged with H. nana, they showed strong resistance to challenges with both eggs and cysticercoids of H. nana from day 20. The immunity became complete from day 30 onward: no tissue cysticercoids or lumenal adults of H. nana were established in these mice. However, when mice were challenged with H. nana 10 or 20 days after 10-day old immature H. microstoma were removed by an anthelmintic, the immunity evoked was directed exclusively against the lumenal phase of the cysticercoid challenge but not the tissue cysticercoids of the egg challenge. When mice experienced the prepatent infection with H. microstoma twice, the immunity evoked was also against the lumenal phase of the egg challenge: the oncospheres developed into tissue cysticercoids but thereafter completely failed to develop into lumenal adult tapeworms. Infection with a single cysticercoid of H. microstoma was shown to be sufficient to evoke immunity against H. nana cysticercoid infections in two strains of mice. Sera from mice which experienced a patent infection with H. microstoma revealed that IgG, IgA, IgM isotypes reacted against oncospheres and cysticercoids of both species, while sera from mice which experienced two prepatent infections reacted with cysticercoids only. Sera from H. microstoma infected mice resistant to H. nana caused precipitations on 4-day-old H. nana in vitro. A correlation exists between the presence of stage specific antibodies and resistance to the different stages.  相似文献   

14.
The biomass of 8-day-old worms of Hymenolepis diminuta in secondary infections, administered to rats 3-10 days after chemotherapeutically expelling a primary infection, was 70-90% less, and the worms were more posteriorly distributed, than in naive controls. The strong depressive effect on growth waned rapidly over 2-5 weeks, but even in rats not challenged until 17 months later, worm growth was weakly depressed by 30%. The extent to which growth was depressed in a secondary infection was independent of the number of worms in the challenge but increased with number of worms in the immunizing infection up to four to eight worms. Further increase up to 64 worms had little effect. This suggests, as it is known that the biomass of worms in a rat reaches a maximum with infections of between five and 10 worms, that the change in the intestine is proportional to biomass, not number, of worms. It is argued that partially suppressed immuno-inflammatory changes in the intestine, which will affect secondary worms so strongly, will also have depressed growth and fecundity effects on the primary worms, that a dynamic equilibrium is reached between the strength of the intestinal response and the biomass of the tapeworm, and that it is reaching this equilibrium, not a 'crowding effect', which limits H. diminuta to a level compatible with the survival of the rat.  相似文献   

15.
Experiments were conducted to examine adult worm burdens, fecal egg output, and in vitro fecundity of Nematospiroides dubius in resistant LAF1 and susceptible CBA mice 12, 15, 18, and 21 days following primary and challenge infections. A strong correlation was obtained on the number of eggs produced by worms cultured in vitro and the egg production as assessed by fecal egg count. Worm counts, fecal egg counts, and in vitro fecundity were similar on all days studied following a primary infection in both mouse strains. However, after challenge infection, LAF1 mice showed lower worm burdens, fecal egg output, and in vitro egg production when compared to CBA mice. Although the egg production of surviving female worms from immune LAF1 mice was decreased, it never fell below a threshold of 100 eggs/day. The reduced fecundity may be a manifestation of a general anti-worm response rather than responses directed specifically at worm reproduction.  相似文献   

16.
In mice concurrently infected with Hymenolepis citelli and Nematospiroides dubius, survival of the tapeworm was prolonged, and there was an impairment of the efferent arm of the response to the cestode. The immunological rejection of a six cysticercoid primary H. citelli infection was delayed by the N. dubius infection. The growth of the cestode was poorer in concurrently infected mice, and this effect was rapid, being evident within 4 days of the N. dubius infection. Maximum biomass in the controls was reached on Day 20, whereas in the concurrently infected mice it was reached on Day 25. The induction of acquired immunity to homologous H. citelli infection was suppressed, although the expression of a secondary response against homologous challenge was not abrogated in doubly infected mice. The results are discussed with reference to the immunodepressive effects the nematode is known to have on heterologous antigenic stimulation.  相似文献   

17.
Roepstorff A. and Andreassen J. 1982. Course of heavy primary infections and earlier immunologically mediated rejection of secondary infections of Hymenolepis diminuta in mice. International Journal for Parasitology12: 23–28. The worms of heavy (50–100 worms) primary Hymenolepis diminuta infections in inbred C57-mice were 1–2 mm long when growth ceased about day 4. Thereafter the mean length decreased by shrinkage and/or ‘decollation’, the worms moved backwards in the small intestine and were rejected from day 6 to day 10. Heavy secondary infections given 14 days after a heavy primary infection were severely stunted (0.2–0.3 mm) but normally situated in the intestine on day 2 and nearly all were rejected by day 4. Even when the time between the primary and secondary infections was increased to 21 or 42 days, therecovery, position and length of the secondary worms were significantly different from primary infections. These results show that an immunologically mediated memory was involved, and that functional antigens can be released from the scolex and/or the neck alone.  相似文献   

18.
The effect of dose and duration of immunizing infections of Heligmosomoides polygyrus on protection against homologous challenge was studied in female TO mice. Primary infections were terminated at various levels with pyrantel embonate (adult infections) or ivermectin (larval infections) and mice were then challenged with 500 infective larvae (L3). The level of protection to secondary challenge positively correlated with the intensity of the primary immunizing infection but truncation of larval infection produced significantly better protection than termination of the adult nematode infection. The duration of the primary larval infection (1-6 days) positively correlated with the level of protection to secondary challenge, antibody responses and the proportion of circulating eosinophils. Histological changes in the gastrointestinal tract, peripheral leucocytic changes and antibody responses of the mice to H. polygyrus adult somatic antigens indicate both a cellular and humoral basis of host immunity to secondary challenge. Although the TO mice are slow responders in that they harbour chronic infections, immunization by intramucosal killing of the larval stage produced strong protection against secondary challenge infection. The presence of dead immunogenic larval stages within the intestinal wall may well be an important factor, since it exposes the host to stage specific antigens at an appropriate location. The implications of the findings for the control of gastrointestinal nematode infections are also discussed.  相似文献   

19.
The effect of the intestinal changes brought about by the expulsion of Trichinella spiralis in rats was studied in relation to the growth and survival of a concurrent infection with Hymenolepis diminuta, a cestode not normally rejected by the rat in low-level infections. Growth of H. diminuta was stunted in rats given T. spiralis just before, or after, infection with H. diminuta, the stunting being more pronounced when the cestode was given closer to the period of inflammation. There was no loss of the cestode from dual-infected rats and no evidence for destrobilation was found. Lower T. spiralis burdens had a correspondingly weaker effect on growth of H. diminuta, and stunting was abolished by administration of the anti-inflammatory drug cortisone acetate. It is concluded that the stunting of H. diminuta is probably due to the non-specific inflammatory component of the rat's response to T. spiralis infection.  相似文献   

20.
When eggs or mouse-derived cysticercoids of Hymenolepis nana were inoculated into previously uninfected congenitally athymic nude (rnu/rnu) rats of an outbred Rowett strain, they failed to mature in the intestinal lumen. They also failed to mature in phenotypically normal (rnu/+) littermates, except when these hosts were treated with cortisone acetate from the beginning of the lumen phase. The Rowett rat, either thymus-deficient or not, was susceptible to tissue cysticercoids but resistant to luminal adults. It is therefore considered to be an unnatural host, at least for mouse-derived H. nana. There was little or no difference in susceptibility to initial tissue cysticercoids between these nude rats and phenotypically normal ones. The normal rats became completely resistant to reinfection with eggs and no secondary cysticercoids developed in their intestinal tissue, whereas the nude rats showed unaltered susceptibility to secondary tissue cysticercoids. Thus, acquired resistance to egg challenge, assessed by the failure of tissue cysticercoid recovery, was thymus-dependent. However, innate resistance to both a primary egg dose, assessed by the low recovery rates of tissue cysticercoids, and to a primary cysticercoid dose, assessed by the failure of luminal adult recovery, were thymus-independent. The effect of cortisone acetate to initiate maturation of H. nana appeared to be unrelated to thymus function. In contrast, all mice, either thymus-deficient or not, were highly susceptible to both phases. The number of worms recovered was more than 10 times greater than that of cysticercoids established in the rat's intestinal tissue.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

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