Protection of cattle against experimental haemorrhagic septicaemia by the capsular antigens of Pasteurella multocida, types B and E.

Aluminum hydroxide adjuvant vaccines containing endotoxin-free capsular antigens of Pasteurella multocida, types B and E, were administered to cattle. Dose dependent serological responses were observed which were similar for both antigens. The immunised cattle were subjected to intravenous challenge by a virulent type E strain. All animals which received the highest vaccine dose survived and all unimmunised control animals died and a vaccine dose-response relationship was obtained. The results of passive mouse protection and indirect haemagglutination tests (type E) on the sera of immunised cattle corresponded with the degree of protection against challenge of the cattle.     

Activation of macrophages by culture fluid of antigen-stimulated spleen cells collected from chickens immunized with Eimeria tenella

The effect of spleen cell factors on the activation of macrophages was investigated in chickens immunized with Eimeria tenella. The abilities of peritoneal macrophages obtained from normal chickens to kill sporozoites of E. tenella and to inhibit intracellular development of Toxoplasma gondii were enhanced by exposing them to 33 and 50% culture fluid of antigen-stimulated spleen cells of chickens immunized with E. tenella. The parasiticidal activity of normal macrophages was also distinctly enhanced by the treatment with culture fluid of phytohemagglutinin-stimulated normal spleen cells. On the other hand, the parasiticidal activity of normal macrophages could not be enhanced by the treatment with culture fluid of antigen-stimulated normal spleen cells under conditions similar to those of culture fluid of antigen-stimulated immune spleen cells. It thus appears that the macrophage activator was induced from immune spleen cells in response to the stimulation by the antigen.     

T cell-mediated immunity to Cowdria ruminantium in mice: the protective role of Lyt-2+ T cells

The inability of athymic nude mice to make a drug-aided recovery from infection with either the Kümm or the Welgevonden stocks of Cowdria ruminantium and their inability to mount an immune response, suggest that immunity in heartwater is cell-mediated. The adoptive transfer of immunity with the spleen cells of mice immune to the Welgevonden stock is supportive evidence. Immune spleen cells depleted of Lyt-2+ T cells are unable to confer resistance to challenge to recipient mice, whereas the depletion of L3T4+ T cells had no effect on the protection conferred by immune spleen cells. This is conclusive evidence that immunity in heartwater is largely cell-mediated. Immune serum, C. ruminantium and complement incubated in the presence of mouse peritoneal macrophages, inhibits the infectivity of the heartwater agent, but not in the absence of macrophages. The decreased resistance to challenge of immune mice treated with gloxazone adds further support to the concept that in heartwater persistence of C. ruminantium in the host is associated with immunity.     

T cell mediated and humoral immunity in a mouse Chlamydia psittaci systemic infection

Immunity against Chlamydia psittaci, an obligate intracellular parasite, was studied in a mouse model of systemic infection. Sera (0.1 ml) and splenic cells (2 X 10(8)) from immunised mice were given intravenously to susceptible mice 16 hours before intravenous challenge with 1 X 10(5) plaque forming units (pfu) of virulent strain AB7. Transfer of immune cells primed with virulent strain AB7 or vaccinal strain 1B, lowered splenic and hepatic colonisation by approximately 5.5 log pfu. Treatment of immune cells with antithymocyte serum plus complement, before transfer, abrogated the protection. Transfer of sera raised against the virulent strain AB7, or the attenuated vaccinal strain 1B, lowered hepatic colonisation by approximately 1.5 log pfu. Sera containing antigenus antibodies, raised against heat-killed chlamydiae from strain AB7 or the non-virulent intestinal strain iB1, were not protective. Cellular immunity is mainly responsible for the observed protection, although humoral immunity may play some role.     

Avian Reovirus Induces an Inhibitory Effect on Lymphoproliferation in Chickens

The cellular immune responses of chickens inoculated with the vaccine strain S-1133 and/or a field isolate VA-1 of avian reovirus (ARV) were studied. Both strains of virus caused inhibition of the phytohaemagglutinin (PHA)-induced lymphoproliferative response of peripheral blood mononuclear cells (PBMC) and splenic mononuclear cells (SMC) during the initial stage from day 4 up to day 10 post-inoculation (PI), with a later return to the normal value. The inhibition in the PHA-induced lymphoproliferation of SMC could be partially overcome by depletion of adherent cells. The supernatant of the PHA-stimulated SMC culture was also checked in vitro for the presence of suppressive factor(s) produced in response to ARV infection. The culture supernatant from chickens at day 5 PI caused significant inhibition of the PHA-induced lymphoproliferation of control birds, suggesting the presence of suppressive factor(s). ARV infection also significantly inhibited IL-2 production on day 5. There was a significant increase in nitric oxide production by the splenic mononuclear cells of chickens inoculated with either strain of ARV.     

牛磺鹅去氧胆酸对小鼠机体cAMP和cGMP含量的影响

为了研究牛磺鹅去氧胆酸(TCDCA)对小鼠机体环磷酸腺苷(cAMP)和环磷酸鸟苷(cGMP)含量的影响,试验用环孢菌素A诱导特异性免疫低下模型,按相应组别对应的剂量对小鼠灌胃给药7 d,获取血清;体外培养正常小鼠腹腔巨噬细胞,用MTT方法筛选TCDCA作用于腹腔巨噬细胞的最佳药物浓度;用最佳药物浓度作用于巨噬细胞后超声破碎,获取上清液;ELISA方法测定血清和上清液中cAMP和cGMP的含量。结果表明:在TCDCA高剂量(0.2 g/kg)组小鼠血清中,cAMP含量极显著高于环孢菌素A组(P<0.01);各组小鼠血清cGMP含量差异不显著(P>0.05);TCDCA促进小鼠腹腔巨噬细胞增殖的体外浓度为1μg/mL、2.5μg/mL、5μg/mL、10μg/mL;1μg/mL、2.5μg/mL、5μg/mL的TCDCA均能显著或极显著提高细胞内cAMP含量(P<0.05或P<0.01),对cGMP含量均没有显著影响。说明TC-DCA能够显著提高正常和免疫抑制小鼠血清中和正常腹腔巨噬细胞内cAMP含量。     

Koala lymphoid cells: analysis of antigen-specific responses.

Bovine serum albumin (BSA) and ovine immunoglobulin (OvIgG) were used to induce humoral immune responses in two koalas which were also painted with 2-4-dinitrofluorobenzene (DNFB) and subsequently tested for local delayed-type hypersensitivity (DTH) reactions. The responses observed support the suggestion that the koala is 'immunologically lazy'. Antibody responses to BSA and OvIgG were not detected until 12 weeks after the initial antigen injection and antigen-specific in vitro proliferative responses by the mononuclear cells (PMC) of immunised animals could not be induced, although these cells did respond to concanavalin A and phytohaemagglutinin. Similarly, DTH responses to DNFB could be elicited in vivo, but took a relatively long time to develop and the PMC of the sensitised koalas were unresponsive to the sensitising antigen in vitro. The absence of proliferation when mixed suspensions of PMC from different koalas were cultured in vitro is consistent with these results.     

B cell and macrophage response in chicks after oral administration of Salmonella typhimurium strains

Despite the fact that, in a number of countries, vaccination programmes are extensively used to control Salmonella infection in poultry, information on the immune mechanisms, especially the cellular response, is still needed. The aim of the study was to characterise the B cell and macrophage response in caecum (IgA+, IgM+, IgG+ cells, macrophages), bursa of Fabricius (IgM+ cells, macrophages), and spleen (IgM+ cells) of chicks after oral administration of a non-attenuated Salmonella (S.) typhimurium wild-type strain (infection) or an attenuated commercial live S. typhimurium vaccine strain (immunisation) to day-old chicks as compared to non-treated control birds using immunohistochemistry and image analysis. In caecum, higher counts of IgM-secreting cells were detected in infected animals compared with the controls from day 5 until day 12 of age. In contrast, in treated groups, IgA-secreting cells were found in higher numbers only between day 8 and 12 of age. Infected birds showed a higher number of IgA+ cells in spleen and bursa of Fabricius compared to the controls. In the bursa of Fabricius of immunised and infected birds, a depletion of strongly stained IgM+ cells and macrophages was established between day 5 and 9 indicating a possibly special and independent role of this organ during the immunological reaction against Salmonella organisms. The results suggest that IgM- and IgA-secreting cells are of importance in the caecal immune response of chickens against Salmonella strains. Immunised chickens always showed a weaker immune reaction compared to infected animals. Present findings regarding the B cell reaction within avian caeca prove a participation of both humoral and cellular immunity in defence against Salmonella strains. Immunohistochemical examination of the cellular response (B cells and macrophages) in relevant organs of chickens may be an important tool to evaluate the immunogenic characteristics of potential Salmonella live vaccine candidates.     

Absence of lymphokine-enhanced macrophage migration in vitro in the Australian brush-tailed opossum, Trichosurus vulpecula

The supernatants from cultures of either opossum or guinea pig splenic lymphocytes, stimulated with phytohaemagglutinin, significantly enhanced the in vitro migration of guinea pig peritoneal macrophages (P greater than 0.001) but not that of opossum peritoneal macrophages. Failure of opossum macrophages to respond to a putative macrophage chemotactic factor might account for the observed paucity of immune granulomas in these animals and help explain the species' susceptibility to tuberculosis.     

The influence of T. evansi infection on the immuno-responsiveness of experimentally infected water buffaloes.

In order to define the immuno-suppressive capacity of Trypanosoma evansi infections in buffaloes on the induction of immune responses against heterologous antigens, infected and non-infected buffaloes were vaccinated against Pasteurella multocida (haemorrhagic septicemia) and were simultaneously immunised with a control antigen, human serum albumin (HSA). Antibody responses against HSA were significantly reduced in T. evansi-infected animals, but no conclusive data were obtained on the antibody responses against P. multocida. Conversely, the local inflammatory response at the site of Pasteurella vaccination, as measured by increase in size, was significantly reduced in T. evansi-infected animals.These results indicate that the inductive capacity to mount humoral and cell-mediated immune responses against heterologous antigens is suppressed in T. evansi-infected animals. Consequently, T. evansi infection might interfere with the development of protective immunity upon heterologous vaccinations and could explain the poor protection of Pasteurella-vaccinated buffaloes in T. evansi-endemic areas of Vietnam.     

Cell-mediated immune responses to sporozoites and macroschizonts of Theileria annulata.

The nature of cell-mediated immune (CMI) responses was studied in cross-bred bovine calves, immunised by attenuated and allogeneic macroschizonts of Theileria annulata. The CMI responses were also investigated in calves, destined to survive or die of tropical theileriosis (Theileria annulata) induced by a virulent dose of sporozoites or macroschizont-infected lymphoblasts. Calves suffering fatal theileriosis showed poor CMI response. Microcytotoxicity assay revealed an enhanced population of specific cytotoxic cells amongst the peripheral blood lymphocytes (PBL) of calves resolving the infection successfully. The E rosette assay showed proliferation of T cells and the assay for macrophage migration inhibition factor (MIF) demonstrated antigen sensitised cells in the PBL. Calves, immunised by allogeneic and attenuated macroschizont-infected lymphoblasts or those recovering from virulent macroschizont-induced infection, showed protective CMI responses with patterns similar to those appearing after non-fatal sporozoite infection.     

Mannan-binding lectin (MBL) in two chicken breeds and the correlation with experimental Pasteurella multocida infection

The present study is the first demonstration of an association of the genetic serum Mannan-binding lectin (MBL) concentration with bacterial infections in chickens. The genetic serum MBL concentration was determined in two chicken breeds, and the association with the specific Pasteurella multocida humoral immune response during an experimental infection was examined. Furthermore, we examined the association of the genetic serum MBL concentration with systemic infection. The chickens with systemic infection had a statistically significant lower mean serum MBL concentration than the rest of the chickens, suggesting that MBL plays an important role against P. multocida. A statistically significant negative correlation was found between the specific antibody response and the genetic serum MBL concentration for both breeds. This indicates that MBL in chickens is capable of acting as the first line of defence against P. multocida by diminishing the infection before the adaptive immune response takes over.     

Epidermal tissue-derived T-cell growth factor, colony stimulating factor and nerve growth factor in chickens.

The purpose of this study was to determine the mechanism of the local cytokine-mediated immune response in the skin of chickens. The incorporation of 3H-thymidine into spleen T lymphocytes from 9-to 10-week-old chickens was augmented by the addition of epidermal tissue culture supernatant (ESN) from 11-day-old embryos. The colony formation of neonatal chicken bone marrow cells in the methylcellulose medium was also significantly increased by addition of ESN. When axonal outgrowth in matrigel was investigated, the embryonal sympathetic ganglion was found to grow axons outwards towards the epidermal tissue specimens. The above results suggest that chicken epidermal cells (probably keratinocytes) produce T-cell growth factor (corresponding to IL-1), colony-stimulating factor for macrophages (M-CSF) and granulocytes (G-CSF), and nerve growth factor (NGF).     

The response of broiler breeder chickens to parenteral administration of avirulent Pasteurella multocida

Broiler breeder chickens were exposed to avirulent Pasteurella multocida at 14, 22, and 34 weeks of age either by stick wing 1 to 3 times or subcutaneously 3 times. Fowl pox vaccine was mixed with the first P. multocida exposure in some groups. Exposure did not impair egg production or hatch of fertile eggs. Challenge with pathogenic P. multocida serotype 1 at 68 weeks indicated that exposure to avirulent P. multocida 2 or 3 times provided better protection than 1 exposure. Mixing fowl pox vaccine with the avirulent P. multocida did not reduce immunity to fowl cholera or fowl pox.     

Pasteurella multocida infection in heterophil-depleted chickens

The present study was aimed at elucidating the role of heterophil granulocytes during the initial infection with Pasteurella multocida subsp. multocida in chickens. Chickens (17 and 19 wk old) were depleted of their heterophil granulocytes by 5-fluorouracil treatment. When the heterophil blood counts were significantly reduced, the birds were inoculated intratracheally with 1.8-4.3 x 10(4) colony-forming units of P. multocida. Twelve, 24, or 48 hr postinoculation, the birds were euthanatized and examined for macroscopic and histologic lesions in the lungs. Bacterial invasion was determined by culture of P. multocida from the spleen. Recruitment of heterophils into the respiratory tract during infection was found to contribute considerably to the lung lesions in chickens and was found to mediate tissue damage, possibly allowing a more rapid systemic spread of P. multocida. However, during progression of the infection, the heterophil-mediated necrosis in chickens seemed to stimulate giant cell demarcation of infected lung tissue, which coincided with the clearance of P. multocida from the spleen, thus hampering further invasion. Consequently, heterophil activation plays a dual role for the outcome of a P. multocida infection in chickens, where it initially seems to promote invasion and systemic spread but subsequently helps limit the infection by giant cell formation and bacterial clearance.     

Epidermal Tissue-Derived T-cell Growth Factor,Colony Stimulating Factor and Nerve Growth Factor in Chickens

The purpose of this study was to determine the mechanism of the local cytokine-mediated immune response in the skin of chickens. The incorporation of 3H-thymidine into spleen T lymphocytes from 9- to 10-week-old chickens was augmented by the addition of epidermal tissue culture supernatant (ESN) from 11-day-old embryos. The colony formation of neonatal chicken bone marrow cells in the methylcellulose medium was also significantly increased by addition of ESN. When axonal outgrowth in matrigel was investigated, the embryonal sympathetic ganglion was found to grow axons outwards towards the epidermal tissue specimens. The above results suggest that chicken epidermal cells (probably keratinocytes) produce T-cell growth factor (corresponding to IL-1), colony-stimulating factor for macrophages (M-CSF) and granulocytes (G-CSF), and nerve growth factor (NGF).     

Cross-reactive cellular and humoral immune responses to Salmonella enterica serovars Typhimurium and Enteritidis are associated with protection to heterologous re-challenge

Chickens infected with Salmonella enterica serovars Typhimurium (ST) and Enteritidis (SE) still represent a major source of human food poisoning via consumption of contaminated meat and eggs. Vaccination represents a sustainable approach to control Salmonella in the chicken and the serovar specificity of immunity has the potential to impact on the need for multivalent vaccines. The issue of cross-reactive immune responses and cross-serovar protection was examined in these experiments. Cellular and humoral immune responses were measured by antigen-specific ELISA and splenocyte proliferation assays during primary infections (with ST and SE) and during a second challenge with homologous or heterologous serovars. Primary infection with ST or SE induced strong lymphocyte proliferation and high levels of specific antibody (IgM, IgG and IgA) responses with substantial serovar cross-reactivity. The occurrence of high levels of splenocyte proliferation and strong antibody responses corresponded to the initiation of clearance with both ST and SE. Re-challenge of ST and SE infection-primed chickens with either serovar resulted in significant levels of protection (assessed by bacterial numbers and rate of clearance) with little difference between homologous or heterologous challenge schedules. Relatively low levels of antigen-specific splenocyte proliferation were detected during secondary infection, which may be caused by splenic T cells exiting to the gut. In contrast, the more rapid specific antibody responses (compared with primary infection controls) indicate the development of a secondary antigen-specific adaptive response. The substantial level of cross-protection between serovars and the level of antigenic cross-reactivity indicates the potential for single serovar live vaccines to protect against both group B and D salmonellae.     

Study of the toxin-producing ability of Pasteurella multocida in mice

Cell-free sonicated extracts and broth cultures of Pasteurella multocida strains of pig origin were examined for their lienotoxicity in mice. P. multocida strains represented capsular types A and D with or without dermonecrotoxic (DNT) activity in the guinea pig skin test. Mouse lienotoxicity test was suitable for determining the toxigenicity of P. multocida strains only when bacterium-free extracts were tested. In that case both toxigenic type A and D strains were lethal to intravenously inoculated mice and caused a remarkable reduction in spleen mass when sublethal doses were used. The extracts of atoxic strains were not lethal and induced splenic hyperplasia. By testing viable cells no correlation was demonstrable between toxin production and virulence of P. multocida to mice. In one experiment the concentrated sterile culture fluids of a toxigenic type D P. multocida and a toxigenic B. bronchiseptica strain were compared. The former caused deaths and splenic atrophy among mice, while the latter was nontoxic and induced slight hyperplasia of the spleen. This fact indicates that P. multocida secretes its toxin into the culture fluid.     

Ground squirrel splenic macrophages bind lipopolysaccharide over a wide range of temperatures at all phases of their annual hibernation cycle

This study evaluates binding of bacterial lipopolysaccharide (LPS) by splenic macrophages from golden-mantled ground squirrels (Spermophilus lateralis, GMGS), a hibernating mammal, at a variety of in vitro incubation temperatures to determine whether this aspect of immune function is effective at low body temperatures. LPS-binding by ground squirrel macrophages was compared to that of rat splenic macrophages. Macrophages were collected from squirrels at discreet stages in their annual cycle and incubated with fluorescein-labeled LPS (LPS-FITC). The percentage of GMGS that bound LPS-FITC did not change as a function of hibernation season or as a function of incubation temperature. The total amount of LPS-FITC bound per cell was similarly unaffected by season or temperature, however, macrophages from torpid squirrels bound more LPS-FITC than cells from normothermic squirrels. Macrophages of golden-mantled ground squirrels bind LPS at a wide range of temperatures throughout their annual cycle; an ability shared between hibernators and non-hibernators alike.