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1.
Histopathological changes and the distribution of T lymphocytes (CD3), B cells (CD79alpha) and IgG secreting plasma cells were recorded in the abomasum and abomasal lymph nodes of goats during early and late post-infection stages with one to four doses of Haemonchus contortus L3. The infiltration of eosinophils, mast cells, CD3(+) T lymphocytes, CD79alpha(+)B cells and IgG(+) plasma cells in the abomasal mucosa increased dramatically from 10dpi onwards, whereas globule leukocytes were observed only during chronic infection. In late post-infection stages abomasal infiltration of globule leukocytes, CD3(+) T lymphocytes, CD79alpha(+)B cells and IgG(+) plasma cells was significantly higher (P<0.05) in reinfected (groups 6-8) than in primarily infected goats (group 5). In the abomasal lymph nodes, marked hyperplasia of lymphoid follicles and medullary cords, with increase of CD3(+) T lymphocytes, CD79alpha(+)B cells and IgG(+) plasma cells was recorded from 10dpi (group 3) onwards. Worm burdens and the severe abomasal response during the late post-infection stages suggests that a rapid expulsion of nematodes did not occur. The prolonged time required for generating globule leukocytes suggested that immune mechanisms dependent of this cell type are of crucial importance in the protective immunity against H. contortus in goats.  相似文献   

2.
The effect of experimental haemonchosis on the number of tissue eosinophils, plasma cells and lymphocyte subpopulations was evaluated in the fundic abomasal region, the pyloric abomasal region and the abomasal lymph node of Blackbelly lambs, which are resistant to infection, and Columbia lambs, which are susceptible to infection. An increase in the number of tissue eosinophils and CD4+ and WC1(+)γδ T-cells was observed in the pyloric abomasal region of Blackbelly lambs and correlated with lower worm burden and greater resistance to infection. Increases in IgA+ plasma cells from the pyloric abomasal region were observed in both infected groups, but there was no difference between the groups. Therefore, increases in IgA+ plasma cells did not explain the resistance observed. Infection caused a significant increase in tissue eosinophils in the abomasal lymph node of Blackbelly lambs and a decrease in the number of CD4+ T-cells in lambs of both breeds. CD8+ T-cells and IgG+ and IgM+ plasma cells were not associated with either infection or resistance. In this work, clear differences were observed in the numbers of CD4+ and WC1(+)γδ T-cells, tissue eosinophils and IgA+ plasma cells between the abomasal regions studied. These differences indicate that the immunological response is not homogenous in all abomasal mucosa and that evaluating the response from a single abomasal region may not be representative of the cellular response across the abomasum.  相似文献   

3.
It has been reported that CD4(+) T lymphocytes are important in acquired immunity to gastrointestinal nematode infection. Whether these lymphocytes are also involved in the immune response of naturally resistant Gulf Coast Native (GCN) sheep to Haemonchus contortus infection remains to be defined. The objective of this study was to determine the role of CD4(+) T lymphocytes in this resistance. Ten GCN lambs were randomly assigned to a control (n=5) or a treatment (n=5) group. The treatment consisted of a series of IV injections with mouse anti-ovine CD4(+) T lymphocyte monoclonal antibodies for a period of 3 weeks. After the second treatment, all lambs were experimentally infected with 10,000 H. contortus infective larvae by oral inoculation. All lambs were monitored for fecal egg counts, blood packed cell volumes, white blood cell differential counts and serum antibody responses on a weekly basis. Fluorescence-activated cell sorter (FACS) analysis was done biweekly to enumerate CD4(+) T lymphocytes in peripheral blood. Necropsies were performed at the end of the study and 10% of the contents of the gastrointestinal tract were preserved for nematode enumeration and identification. Also at necropsy, mesenteric lymph nodes were extracted and FACS analysis was run on lymphoid cells. Mean fecal egg counts on day 21 and 28 post-infection and nematode counts at necropsy of the treated group were significantly (p<0.05) higher than that of the control group. Percent CD4(+) T lymphocytes in peripheral blood was significantly (p<0.05) lower in the treatment group than in the control group from day 9 to the end of the study. No differences were found in blood packed cell volumes, white blood cell differential counts, antibody titer or lymph node CD4(+) lymphocytes between groups. Lambs depleted of their CD4(+) T lymphocytes were more susceptible to H. contortus infection than undepleted lambs. The results of this study suggest that CD4(+) T lymphocytes are associated with the natural resistance of GCN sheep to H. contortus infection.  相似文献   

4.
Following challenge with Trichosirongylus colubrifonizis, increased numbers of T-cells and immunoglobulin responses are seen in the intestine of sheep immunised by repeated infection with live worms. IL-6 mRNA expression in the small intestine from T. colubriformis-immunised and naive sheep was determined by in situ hybridisation, whereas CD4(+), IgA(+), IgG(+) cells in the gut were evaluated by immunohistochemistry. There was constitutive expression of IL-6 mRNA by cells in the naive gut, and the number of these cells was increased by parasite challenge. There were corresponding increases in numbers of CD4(+) and TCR gamma/delta(+) T-cells and IgG(+) B-cells. Our data are consistent with a role for IL-6, perhaps produced by CD4(+) and/or TCR gamma/delta(+) T-cells or B-cells, in B-cell terminal differentiation. Infiltration of B-cells, particularly IgG(+) B-cells, may reflect parasite immunity in the host.  相似文献   

5.
The pattern of in vivo uptake of albendazole (ABZ) and its major metabolite, ABZ-sulphoxide (ABZSO), by Haemonchus contortus and Fasciola hepatica recovered from ABZ-treated sheep, was investigated. Concentration profiles of both compounds were simultaneously measured in target tissues/fluids from the same infected sheep. In addition, the proportion of the (+) and (-) ABZSO enantiomers was determined in plasma, bile and F. hepatica recovered from treated sheep. Sheep naturally infected with H. contortus were intraruminally (i.r.) treated with ABZ (micronized suspension, 7. 5mg/kg) and the plasma concentrations of ABZSO and ABZ-sulphone (ABZSO(2)) determined in addition to the concentration of ABZ and ABZSO in H. contortus, abomasal mucosa and fluid content samples. In addition, F. hepatica artificially infected sheep were treated i.r. with the same ABZ suspension (7.5mg/kg), and samples of blood, bile, liver tissue and adult flukes were collected and analysed by HPLC to determine the concentrations of ABZ and both enantiomers of ABZSO. ABZSO and ABZSO(2) were the analytes recovered in plasma with ABZ and ABZSO present in H. contortus. ABZ was the analyte recovered at the highest concentration in H. contortus and abomasal mucosa, whereas higher concentrations of ABZSO were measured in abomasal fluid content. Only low concentrations of ABZ were detected in F. hepatica and bile, but markedly higher concentrations of ABZ were measured in liver tissue. ABZSO was the main molecule recovered in F. hepatica, plasma and bile samples collected from ABZ-treated sheep. The (+) enantiomer of ABZSO was recovered at a higher proportion in plasma (75%), bile (78%) and F. hepatica (74%) after ABZ administration to infected sheep.  相似文献   

6.
Cimetidine, a histamine H2-receptor blocking agent which reduces gastric acid flow in simple stomach animals was administered directly into the abomasum of sheep at 100 mg kg-1 twice daily for five consecutive days and again on the eighth day. The drug caused a significant increase in the pH values of the abomasal contents and was highly effective in reducing the adult population of Haemonchus contortus (100 per cent) and Ostertagia circumcincta (70 per cent) in the abomasum of sheep. The possibility of using cimetidine as a method of treating abomasal nematode parasitism is discussed.  相似文献   

7.
Nine- to 10-month-old Florida Native, St. Croix and Dorset/Rambouillet sheep were infected with Haemonchus contortus. The primary infection was terminated by anthelmintic treatment 9 weeks later and animals were then reinfected with H. contortus. Dorset/Rambouillet sheep showed higher fecal egg counts and decreased packed cell volumes and plasma protein levels compared with the other two breeds during the primary infection. However, no breed differences were found in total worm burdens in either primary or secondary infection. Differences between breeds were also not detected in lymphocyte responsiveness to parasite antigen, H. contortus specific mucosal antibody levels, numbers of abomasal mast cells and globule leukocytes or abomasal histamine levels.  相似文献   

8.
Selection of resistant animals and host immunization have been proposed as alternative methods for the control of gastrointestinal nematode parasites. However, a better knowledge of the mechanisms involved in protective immunity against these parasites is required for the development of optimal strategies. In this study, 3 month old INRA 401 lambs (n = 81) were allocated into three groups: uninfected control, challenged either once (primary-infected animals) or twice (previously-infected animals) with 10,000 Haemonchus contortus L3. Uninfected control and challenged animals were sequentially sacrificed at 3, 7, 15 and 28 days post challenge. In both challenged groups, a clear Th2-oriented immune response was observed in the abomasal lymph node and mucosa. IL-4 and IL-13 mRNA over-expression, recruitment of eosinophils, mast cells and globule leukocytes and production of specific systemic IgG and mucosal IgA were observed earlier in previously-infected animals than in primary-infected ones. At 28 days post infection, no differences between intensities of these responses were observed between the challenged groups. Worm establishment rates were similar in previously-infected and primary-infected lambs. However, reductions of worm development, female fecundity and fecal egg output were observed in previously-infected sheep. We conclude that H. contortus infection in young INRA 401 lambs induced an unequivocal Th2 immune response resulting in the regulation of worm egg production without affecting their establishment.  相似文献   

9.
Histopathological changes and the distributions of T and B lymphocytes and IgG producing plasma cells were recorded in the abomasum and abomasal lymph nodes of goats 3, 7 and 21 weeks post-infection (wpi) after an experimental infection with H. contortus. The low rate of worm recovery by 3 wpi (5.6%) might have been due to larvae death as suggested by the presence of granulomas in the abomasal mucosa at 3 and 7 wpi, or simply due to a poor larval establishment. Marked increase in the secretion of mucus by mucous cells together with an abundant infiltration of eosinophils, mast cells, CD3+ T lymphocytes, CD79a+ B cells, IgG+ plasma cells and globule leukocytes were recorded in the abomasal mucosa, especially at 7 wpi. Except for the globule leukocytes, this reaction decreased substantially by week 21, suggesting this cell type may have been involved in rejection of adult nematodes. The abomasal lymph nodes showed marked hyperplasia, particularly of CD79a+ B cells and IgG+ plasma cells in all infected goats. These reactions may have been responsible for the reduction in the number of worms found in the abomasum between 3 and 7 wpi.  相似文献   

10.
Serum and abomasal IgA, IgG and IgM antibody response against adult worm, L3 and egg antigens of Haemonchus contortus was monitored by the ELISA technique after one or two infections with this nematode. Following the first infection, antibody levels in serum did not change materially. After administration of a challenge dose of infective larvae, antibodies of the three immunoglobulin classes in infected animals rose slightly, but this rise appeared later than the fall in the faecal egg counts. In contrast, in abomasal mucosa, IgA anti-larval antibody levels, which did not increase materially after the primary infection, rose rapidly after a transient inhibition when sheep were challenged. A close temporal relationship was observed between the rise in local anti-worm IgA antibodies and the self-cure reaction, but antibody levels fell rapidly after worm diminution. The local antibody response was thus considered to be related to immunity of sheep to H. contortus.  相似文献   

11.
12.
The effect of Taenia hydatigena larvae vesicular concentrate (ThLVC) on the establishment of an experimental infection by Haemonchus contortus was evaluated. The lambs that received ThLVC showed a greater (P<0.05) average of blood eosinophils (BE) than the lambs that did not receive ThLVC. Lambs that were only infected with H. contortus larvae showed a fecal egg count (FEC) and an adult phase (AP) number greater (P<0.05) than lambs that received ThLVC prior to infection. No effect was observed in size and prolificacy of AP after the administration of ThLVC. The infection with H. contortus caused an increase (P<0.05) in CD4+ lymphocytes in abomasal lymph node (ALN) and the combination of ThLVC plus the infection with H. contortus caused an increase (P<0.05) in CD4+ lymphocytes in the abomasal wall (AW). In addition, a positive correlation between gamma-delta lymphocytes of ALN (r=0.73, P<0.05) with the presence of AP in the abomasum was observed. The quantity of plasma cells in ALN and AW was not affected by the administration of ThLVC nor related to the resistance observed. The results shown in this work leave no doubt that ThLVC administration prior to inoculation produces eosinophilia and partially protects against the establishment of H. contortus. However, this protection is not only attributable to the role of eosinophils, since ThLVC can function stimulating other immune response cells, such as T lymphocytes, both contributing to prevent the presence of worms.  相似文献   

13.
Immunization of cattle with in vitro propagated bovine mononuclear cells infected with Theileria annulata induces a protective immune response. Activation and effector function of T cells exiting the lymph node draining the site of cell line immunization were investigated to understand the mechanisms involved in the generation of immunity. Immunized animals exhibited a biphasic immune response in efferent lymph as well as peripheral blood. The first phase corresponded to allogenic responses against MHC antigens of the immunizing cell line and the second was associated with parasite specific responses. An increase in the output of CD2(+) cells and MHC class II(+) cells in efferent lymph was observed after cell line immunization with a corresponding decrease in WC1(+) cells. Although the percentage of CD4(+) T cells did not change significantly over the course of the experiment, they became activated. Both CD25 and MHC class II expressing CD4(+) T cells were detected from day 7 onwards, peaking around day 13. Efferent lymph leukocytes (ELL) exhibited sustained responses to IL-2 in vitro following cell line immunization. Antigen specific proliferation was also detected first to the immunizing cell line and then to parasite antigens. The two peaks of CD2(+) cells were observed, which corresponded to similar peaks of CD8(+) cells. The increase in CD8(+) cells was more pronounced during the second parasite specific phase than the first allogenic phase. Activated CD8(+) T cells mainly expressed MHC class II and some expressed CD25. Significantly the peak of activated CD4(+) T cells preceded the peak of activated CD8(+) T cells, highlighting the role of T. annulata specific CD4(+) T cells in inducing parasite specific CD8(+) cytotoxic responses. A biphasic cytotoxic response also appeared in efferent lymph and peripheral blood, the first directed against MHC antigens of the immunizing cell line followed by MHC class I restricted parasite specific cytotoxicity. The cytotoxic responses in efferent lymph appeared earlier than peripheral blood, suggesting that activated CD8(+) cells exiting the draining lymph node following immunization with T. annulata infected schizonts play an important role in the development of protective immune responses.  相似文献   

14.
Canaria Hair Breed (CHB) sheep are more resistant than Canaria sheep (CS) to experimental Haemonchus contortus infection. Protective responses appear effective against the adult stage of the parasite, not as commonly reported in other breeds against the larval stages. In this study we have quantified several abomasal immune cells and correlated these with parasitological variables for each breed. A significant negative correlation between CD4+ T cell numbers and worm burden or length at 28 dpi was seen only in CS sheep. Significant negative correlations for both abomasal eosinophils and γδ/WC1+ T cells, and fecundity of the adult worms were observed only in the resistant CHB sheep breed. Tissue eosinophils and γδ/WC1+ T cells were positively correlated in CHB sheep. We suggest that the two sheep breeds have disparate immune responses following infection with the parasite and that γδ+ T cells in association with eosinophils may play a hitherto unrecognised role in modulating fecundity in H. contortus adult female parasites.  相似文献   

15.
Disphenol was administered to sheep infected with Haemonchus contortus in order to prevent the development of populations of adult worms, and studies were made of the pathogenicity of the arrested fourth-stage larvae which remained. The treated sheep showed elevated plasma pepsinogen and abomasal pH, predominantly negative dry-matter balance, and evidence of greater fluid loss, including plasma, into the gastro-intestinal tract. It was concluded that arrested larvae may cause damage to the abomasal mucosa.  相似文献   

16.
T-cells have been implicated both, in promoting and reducing viral replication during lentivirus infection. CD8+ lymphocytes are believed to be important in controlling viral load through direct killing of virus-infected cells and by secretion of inhibitory chemokines and cytokines. To evaluate the role of CD8+ T-cells in the induction and control of the primary phase of a lentivirus infection, we have used a non-T-cell tropic lentivirus, maedi-visna virus (MVV), to study the initial pathogenesis and subsequent immune responses in sheep depleted in vivo of CD8+ cells. Sheep were depleted of CD8+ cells in both blood and efferent lymph for up to 14 days. No difference in MVV replication was observed in either the draining efferent lymph or lymph node of these sheep. Surprisingly, these animals displayed a normal induction of pCTL whereas the virus-specific proliferative responses were reduced. This could reflect either that a proportion of functional CD8+ lymphocytes remained in these animals, as suggested by the appearance of pCTLs, or that CD8+ cells are not required for control of primary MVV infection.  相似文献   

17.
To investigate the contribution of different bovine cell subpopulations in the development of in vitro induced responses by Ostertagia ostertagi third larval antigen extract (L3), bovine abomasal lymph node cell suspensions were depleted of specific cell populations. The depleted cell suspensions were subsequently assayed for their proliferative responses to O. ostertagi L3 antigen extract. Proliferative responses to O. ostertagi L3 antigen extract were restricted to a CD2+ CD4- CD8- cell population and MHC II+ cells different from B-cells were of major importance. Depletion of CD4, CD8, CD4CD8, IgM or CD21 positive cells did not decrease proliferation to L3 antigen extract. Depletion of gammadelta T-cells, which also comprise a subpopulation of CD2+ CD4- CD8- cells, reduced proliferation to L3 antigen extract only in one animal. The results suggest that either gammadelta T-cells could be involved in the proliferation or that another as yet unidentified population is important for proliferation. The precise role of these populations during infection with O. ostertagi and the mechanism by which these cells may influence the host immune response are important issues that remain to be elucidated.  相似文献   

18.
Serum pepsinogen concentrations rose more rapidly and to higher levels in adult sheep infected with Ostertagia circumcincta and treated orally with the mast cell stabilising agent sodium cromoglycate than they did in adult sheep infected with the parasite which remained untreated. Sodium cromoglycate did not affect the serum pepsinogen concentrations or abomasal pH in uninfected sheep.  相似文献   

19.
Jembrana disease virus (JDV) is an unusual bovine lentivirus that causes an acute and sometimes fatal disease after a short incubation period in Bali cattle (Bos javanicus). The pathological changes occur primarily in lymphoid tissues, which feature proliferating lymphoblastoid-like cells predominantly throughout parafollicular (T-cell) areas, and atrophy of follicles (B-cell) areas. Five Bali cattle were experimentally infected with JDV and all developed typical clinical signs of Jembrana disease characterised by a transient febrile response, enlargement of superficial lymph nodes and a significant leukopenia. Flow cytometric analysis of PBMC during the acute (febrile) disease phase showed that the reduced number of lymphocytes was due to a significant decrease in both the proportion and absolute numbers of CD4(+) T cells, but not CD8(+) T-cells or CD21(+) B-cells. At the end of the febrile phase, total numbers of both CD8(+) T-cells and CD21(+) B-cells increased significantly, while CD4(+) T-cell numbers remained below normal values, resulting in a significantly reduced CD4(+):CD8(+) ratio. We speculate that the persistent depletion of CD4(+) T cells following JDV infection, through lack of CD4(+) T cell help to B cells, may explain the lack of production of JDV-specific antibodies for several weeks after recovery despite an increase in CD21(+) B cell numbers. Further, our previous data showing that IgG(+) plasma cells are targets for JDV infection, correlated with our current data demonstrating an increase in CD8(+) T cell numbers, supports the suggestion that anti-viral cytotoxic T cell or other cell-mediated immune responses may be critical in the recovery process, although this remains to be formally demonstrated for JDV.  相似文献   

20.
Primary and secondary serum antibody responses to Haemonchus contortus were studied in Castellana sheep. Ten-month-old sheep were infected (200 L3/kg live weight (lw)) and challenged (400 L3/kg lw) or uninfected and equally challenged with H. contortus. Primary infections induced a partially protective response upon challenge, characterized by higher serum protein levels, longer prepatent periods, lower fecal egg counts, and significant reduction in the establishment rate of the parasite and abomasal adult and L4 worm burdens. The resistant status of the infected and challenged sheep was not clearly related either to the serum specific antibody levels (IgG: IgG1, IgG2; IgM; IgA) estimated by ELISA or to immunodetection patterns in the Western blots.  相似文献   

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