Assessing humoral and cell-mediated immune response in Hawaiian green turtles, Chelonia mydas

Seven immature green turtles, Chelonia mydas, captured from Kaneohe Bay on the island of Oahu were used to evaluate methods for assessing their immune response. Two turtles each were immunized intramuscularly with egg white lysozyme (EWL) in Freund's complete adjuvant, Gerbu, or ISA-70; a seventh turtle was immunized with saline only and served as a control. Humoral immune response was measured with an indirect enzyme linked immunosorbent assay (ELISA). Cell-mediated immune response was measured using in vitro cell proliferation assays (CPA) using whole blood or peripheral blood mononuclear cells (PBM) cultured with concanavalin A (ConA), phytohaemagglutinin (PHA), or soluble egg EWL antigen. All turtles, except for one immunized with Gerbu and the control, produced a detectable humoral immune response by 6 weeks which persisted for at least 14 weeks after a single immunization. All turtles produced an anamnestic humoral immune response after secondary immunization. Antigen specific cell-mediated immune response in PBM was seen in all turtles either after primary or secondary immunization, but it was not as consistent as humoral immune response; antigen specific cell-mediated immune response in whole blood was rarely seen. Mononuclear cells had significantly higher stimulation indices than whole blood regardless of adjuvant, however, results with whole blood had lower variability. Both Gerbu and ISA-70 appeared to potentiate the cell-mediated immune response when PBM or whole blood were cultured with PHA. This is the first time cell proliferation assays have been compared between whole blood and PBM for reptiles. This is also the first demonstration of antigen specific cell-mediated response in reptiles. Cell proliferation assays allowed us to evaluate the cell-mediated immune response of green turtles. However, CPA may be less reliable than ELISA for detecting antigen specific immune response. Either of the three adjuvants appears suitable to safely elicit a detectable immune response in green turtles.     

Maternal immunity enhances systemic recall immune responses upon oral immunization of piglets with F4 fimbriae

F4 enterotoxigenic Escherichia coli (ETEC) cause diarrhoea and mortality in piglets leading to severe economic losses. Oral immunization of piglets with F4 fimbriae induces a protective intestinal immune response evidenced by an F4-specific serum and intestinal IgA response. However, successful oral immunization of pigs with F4 fimbriae in the presence of maternal immunity has not been demonstrated yet. In the present study we aimed to evaluate the effect of maternal immunity on the induction of a systemic immune response upon oral immunization of piglets. Whereas F4-specific IgG and IgA could be induced by oral immunization of pigs without maternal antibodies and by intramuscular immunization of pigs with maternal antibodies, no such response was seen in the orally immunized animals with maternal antibodies. Since maternal antibodies can mask an antibody response, we also looked by ELIspot assays for circulating F4-specific antibody secreting cells (ASCs). Enumerating the F4-specific ASCs within the circulating peripheral blood mononuclear cells, and the number of F4-specific IgA ASCs within the circulating IgA⁺ B-cells revealed an F4-specific immune response in the orally immunized animals with maternal antibodies. Interestingly, results suggest a more robust IgA booster response by oral immunization of pigs with than without maternal antibodies. These results demonstrate that oral immunization of piglets with F4-specific maternal antibodies is feasible and that these maternal antibodies seem to enhance the secondary systemic immune response. Furthermore, our ELIspot assay on enriched IgA⁺ B-cells could be used as a screening procedure to optimize mucosal immunization protocols in pigs with maternal immunity.     

Astaxanthin stimulates cell-mediated and humoral immune responses in cats

Astaxanthin is a potent antioxidant carotenoid and may play a role in modulating immune response in cats. Blood was taken from female domestic shorthair cats (8-9 mo old; 3.2 ± 0.04 kg body weight) fed 0, 1, 5 or 10mg astaxanthin daily for 12 wk to assess peripheral blood mononuclear cell (PBMC) proliferation response, leukocyte subpopulations, natural killer (NK) cell cytotoxic activity, and plasma IgG and IgM concentration. Cutaneous delayed-type hypersensitivity (DTH) response against concanavalin A and an attenuated polyvalent vaccine was assessed on wk 8 (prior to vaccination) and 12 (post-vaccination). There was a dose-related increase in plasma astaxanthin concentrations, with maximum concentrations observed on wk 12. Dietary astaxanthin enhanced DTH response to both the specific (vaccine) and nonspecific (concanavalin A) antigens. In addition, cats fed astaxanthin had heightened PBMC proliferation and NK cell cytotoxic activity. The population of CD3(+) total T and CD4(+) T helper cells were also higher in astaxanthin-fed cats; however, no treatment difference was found with the CD8(+) T cytotoxic and MHC II(+) activated lymphocyte cell populations. Dietary astaxanthin increased concentrations of plasma IgG and IgM. Therefore, dietary astaxanthin heightened cell-mediated and humoral immune responses in cats.     

Peripheral white blood cell counts throughout pregnancy in non-aborting Neospora caninum-seronegative and seropositive high-producing dairy cows in a Holstein Friesian herd

Pregnancy is characterized by transient changes in the maternal immune system, also evident at peripheral level. The present study analyzes the kinetics and possible factors affecting peripheral white blood cell populations throughout pregnancy in a herd of high-producing dairy cows chronically infected or not with Neospora caninum. We examined 54 pregnant parous cows: 29 Neospora-seronegative and 25 Neospora-seropositive cows. Blood samples were collected on Days 90, 120, 150, 180 and 210 of gestation. General Linear Model (GLM) repeated measures analysis of variance showed that the interaction Neospora-seropositivity × parity significantly affected total leukocyte, neutrophil and monocyte counts with lower levels of total leukocytes, lower neutrophil and higher monocyte counts recorded in primiparous Neospora-seropositive cows. In addition, N. caninum-seropositive cows had significantly increased monocyte counts on Day 180 of gestation compared to seronegative ones. Other factors significantly associated with changes in total and/or differential leukocyte profiles were period of pregnancy, season, twin pregnancy and milk production. In conclusion, a parity-associated effect of chronic N. caninum infection was observed on peripheral blood cell profiles in dairy cattle during gestation.     

Dietary astaxanthin enhances immune response in dogs

No information is available on the possible role of astaxanthin on immune response in domestic canine. Female Beagle dogs (9-10 mo old; 8.2 ± 0.2 kg body weight) were fed 0, 10, 20 or 40 mg astaxanthin daily and blood sampled on wk 0, 6, 12, and 16 for assessing the following: lymphoproliferation, leukocyte subpopulations, natural killer (NK) cell cytotoxicity, and concentrations of blood astaxanthin, IgG, IgM and acute phase proteins. Delayed-type hypersensitivity (DTH) response was assessed on wk 0, 12 and 16. Plasma astaxanthin increased dose-dependently and reached maximum concentrations on wk 6. Dietary astaxanthin enhanced DTH response to vaccine, concanavalin A-induced lymphocyte proliferation (with the 20mg dose at wk 12) and NK cell cytotoxic activity. In addition, dietary astaxanthin increased concentrations of IgG and IgM, and B cell population. Plasma concentrations of C reactive protein were lower in astaxanthin-fed dogs. Therefore, dietary astaxanthin heightened cell-mediated and humoral immune response and reduced DNA damage and inflammation in dogs.     

Longitudinal evaluation of CD4+ and CD8+ peripheral blood and mammary gland lymphocytes in cows experimentally inoculated with Staphylococcus aureus.

Staphylococcus aureus is a major pathogen associated with mastitis, a disease affecting both women and dairy cows. The longitudinal profiles of bovine peripheral blood and mammary gland lymphocyte phenotypes in response to S. aureus-induced mastitis were investigated in dairy cows. Increased percentage of CD4 lymphocytes in the mammary gland between 1 and 8 days post-inoculation, increased milk CD4 protein density per cell between 1-8 days post-inoculation, and a statistically significant negative correlation between post-inoculation bacterial counts in milk and blood lymphocyte CD4 protein density were found. Together with blood and milk leukocyte counts, the milk lymphocyte CD4/CD8 ratio and the milk lymphocyte CD4 protein density were more informative indicators than milk somatic cell counts and bacteriology for identification of early vs. late inflammatory phases. These findings suggest that CD4+ lymphocytes play a protective role in the early stages of S. aureus-induced mastitis.     

Identification of Ehrlichia ruminantium proteins that activate cellular immune responses using a reverse vaccinology strategy

Ehrlichia ruminantium is an obligate intracellular bacterial pathogen which causes heartwater, a serious tick-borne disease of ruminants throughout sub-Saharan Africa. The development of promising recombinant vaccines has been reported previously, but none has been as effective as immunisation with live organisms. In this study we have used reverse vaccinology to identify proteins that elicit an in vitro cellular immune response similar to that induced by intact E. ruminantium. The experimental strategy involved four successive steps: (i) in silico selection of the most likely vaccine candidate genes from the annotated genome; (ii) cloning and expression of the selected genes; (iii) in vitro screening of the expressed proteins for their ability to induce interferon-gamma (IFN-γ) production in E. ruminantium-immune lymphocytes; and (iv) further examination of the cytokine response profiles of those lymphocytes which tested positive for IFN-γ induction. Based on their overall cytokine induction profiles the recombinant proteins were divided into four distinct groups. Eleven recombinant proteins induced a cytokine profile that was similar to the recall immune response induced by immune peripheral blood mononuclear cells (PBMC) stimulated with intact E. ruminantium. This response comprised the upregulation of cytokines associated with adaptive cellular immune responses as well as innate immunity. A successful vaccine may therefore need to contain a combination of recombinant proteins which induce both immune pathways to ensure protection against heartwater.     

Age-related alterations to immune parameters in Labrador retriever dogs

In order to assess age-related changes in the immune status of Labrador retriever dogs, leukocyte phenotypes, lymphocyte proliferative capacity, and serum antibody levels were measured in four cohorts of dogs, ranging from 2 to 10 years of age. Absolute numbers of white blood cells, lymphocytes, monocytes, granulocytes, and CD3+, CD4+, CD8+ and CD21+ lymphocytes significantly decreased with increasing age. Relative percentages of lymphocytes and CD4 cells were significantly decreased, and relative percentages of granulocytes and CD8 cells significantly increased, with age. The CD4:CD8 ratio showed a significant age-related decrease. Proliferative responses of T-cells to mitogens in whole-blood cultures either increased (Concanavalin A) or remained the same (phytohemagglutinin) with age when data was normalised to allow for differences in responding cell number. Similarly, normalised data of proliferative response to anti-CD3 stimulation together with phorbol 12-myristate 13-acetate showed an age-related increase. Serum levels of total IgA significantly increased with age whereas total IgG levels remained unchanged. These observations illustrate a significant change to a number of immune parameters with age. However, further work is required to determine whether the differences reported here are sufficient to cause overt or functional immune senescence in Labrador retriever dogs.     

Detection of impaired T cell-mediated immune responses to herpesvirus (BHV-1) in cattle

Interleukin 2 (IL-2) functions in the regulation of cell-mediated immune responses both in vivo and in vitro. Therefore, IL-2 production has been studied in patients with immunological disorders to determine the level of the immune defect. However, the cause(s) of low responses to selected antigens by cells from clinically normal individuals has not been examined. The ability of cells from clinically normal individual cattle to produce and respond to IL-2 was investigated as a measure of specific cell-mediated immune response. Cells from the majority of animals (6/7 in a representative experiment) could produce IL-2 in response to mitogen or a specific antigen, Bovine Herpesvirus 1 (BHV-1). Proliferation of lymphocytes from the majority of low responding animals (2/3 and 4/4 in separate experiments) could be restored to a level similar to high responders by the addition of exogenous IL-2 after endogenous IL-2 depletion. IL-2 receptor expression was indirectly assessed by the ability of activated cells to absorb IL-2. One individual's cells were incapable of absorbing exogenous IL-2 and failed to proliferate indicating a lack of activation and expression of receptors. In addition, exogenous IL-2 was able to enhance proliferation of both high and low responders in the presence of endogenous IL-2. These results suggest that proliferation of bovine peripheral blood mononuclear cells is dependent on the presence of IL-2. In addition, IL-2 production can be used to measure specific cell-mediated immune responses.     

猪传染性胸膜肺炎与猪肺疫二联亚单位疫苗的免疫效果评价

为了评价猪传染性胸膜肺炎与猪肺疫二联亚单位疫苗(由多杀性巴氏杆菌外膜蛋白H (OmpH)质粒导入胸膜肺炎放线杆菌(APP)菌影制备)的免疫效果,于某规模化猪场选取30头无上述病原菌和抗体的4周龄(w)仔猪,随机分为安全评估组和试验组进行免疫,试验组包括APP组、OmpH组、APP+OmpH联苗组,分别于4、6w肌肉注射...     

Genome-wide identification of runs of homozygosity islands in the Gyr breed (Bos indicus)

Runs of homozygosity (ROH) are contiguous homozygous regions of the genome. These regions can be used to identify genes associated with traits of economic interest, as well as inbreeding levels. The aim of the present study was to analyse the length and distribution of ROH islands in Gyr cattle and to identify genes within these regions. A population of 173 animals selected for beef production and a population of 291 animals selected for dairy production were used. Differences in the number of short ROH (ROH_{1-2 Mb}) were observed between the two populations, while the number of long ROH (ROH_{>16 Mb}) was similar. ROH islands with the highest incidences (>0.50) overlapped in several segments of the genome in the two populations. The genes identified were associated with milk production, growth, reproduction, immune response and resistance traits. Our results contribute to the understanding of how selection can shape the distribution of ROH and ROH islands within the same breed when animals are selected for different purposes such as dairy or beef production.     

Effects of pulsed or continuous infusion of cortisol on immune function in sheep

It was postulated that frequent pulses of cortisol such as might be induced by a repeated or chronic stressor, could induce immune suppression and that the effect would be greater than in animals subjected to less frequent increases. Four groups of nine adult Scottish Blackface ewes were infused for 14 d with saline or hydrocortisone hemisuccinate (cortisol) delivered continuously or in pulses. Plasma concentrations of cortisol were significantly elevated (to between approximately 100 and 1000 nmol/liter; P < 0.001) for about 30 or 75 min after infusion of pulses of hydrocortisone hemisuccinate at intervals of 1 hr (P1) or 6 hr (P6), respectively. In animals continuously infused (CI), they were consistently elevated (P < 0.001), compared with concentrations in control animals infused with saline only (S), to approximately 1000 nmol/liter or more. Antibody production in response to ovalbumin injection was not affected by any of the infusion regimes. At Days 10, 24, and 31 after injection of ovalbumin and initiation of the infusion, rates of multiplication of unstimulated lymphocytes, in vitro, were greater (P < 0.05) in P6 animals than in saline-infused, control animals and this resulted in a reduction in the stimulated lymphocyte response. As a consequence of the increased basal lymphocyte activity, after Day 0, the corrected, stimulated lymphocyte response of P6 animals was consistently below that of controls (P < 0.05 at Day 24). Both mean basal and stimulated lymphocyte activities in CI and P1 animals were similar to those of controls. The gamma interferon (IFN-gamma) response was generally small and not affected by treatment. It is concluded that large, relatively infrequent increases in circulating cortisol concentrations can modify the cell mediated immune response such that the response to a specific antigen challenge is compromised but smaller, more frequent pulses had no effect. Elevated cortisol concentrations per se did not have a significant inhibitory effect on the immune system.     

Role of the bovine immune system and genome in resistance to gastrointestinal nematodes

Gastrointestinal nematode infections of cattle remain a constraint on the efficient raising of cattle on pasture throughout the world. Most of the common genera of parasites found in cattle stimulate an effective level of protective immunity in most animals within the herd after the animals have been on pasture for several months. In contrast, cattle remain susceptible to infection by Ostertagia for many months, and immunity that actually reduces the development of newly acquired larvae is usually not evident until the animals are more than 2 years old. This prolonged susceptibility to reinfection is a major reason that this parasite remains the most economically important GI nematode in temperate regions of the world. Although, animals remain susceptible to reinfection for a prolonged period of time, there are a number of manifestations of the immune response that result in an enhanced level of herd immunity. These include a delay in the development time of the parasites, an increase in the number of larvae that undergo an inhibition in development, morphological changes in the worms, stunting of newly acquired worms, and most importantly a reduction in the number of eggs produced by the female worms. The overall result of these manifestations of immunity is a reduction in parasite transmission within the cattle herd. The immune mechanisms responsible for these different types of functional immunity remain to be defined. In general, GI nematode infections in mammals elicit very strong Th2-like responses characterized by high levels of Interleukin 4 (IL4), high levels of IgG1 and IgE antibodies, and large numbers of mast cells. In cattle, the most extensively studied GI nematode, in regards to host immune responses, is Ostertagia ostertagi. In Ostertagia infections, antigens are presented to the host in the draining lymph nodes very soon after infection, and within the first 3-4 days of infection these cells have left the nodes, entered the peripheral circulation, and have homed to tissues immediately surrounding the parasite where they become established. The immune response seen in the abomasum is in many ways are similar to that seen other mammalian hosts, with high levels of expression of IL4 in the draining lymph nodes and in lymphocytes isolated from the mucosa. But unlike a number of other systems, lymphocyte populations taken from Ostertagia infected cattle seem to be up-regulated for a number of other cytokines, most notably Interferon (IFN, implying that in Ostertagia infections, the immune response elicit is not simply a stereotypic Th2 response. In addition, effector cell populations in the tissues surrounding the parasites, are not typical, inferring the Ostertagia has evolved means to suppress or evade protective immune mechanisms. Studies have also demonstrated that the number of nematode eggs/gram (EPG) in feces of pastured cattle is strongly influenced by host genetics and that the heritability of this trait is approximately 0.30. In addition, EPG values are not "normally" distributed and a small percentage of a herd is responsible for the majority of parasite transmission. This suggests that genetic management of a small percentage of the herd can considerably reduce overall parasite transmission. A selective breeding program has been initiated to identify the host genes controlling resistance/susceptibility to the parasites. The best indicator of the number of Cooperia infecting a host is the EPG value, while Ostertagia is best measured by serum pepsinogen levels, weight gain, and measures of anemia. Other phenotypic measures are either not significantly associated with parasite numbers or are very weakly correlated. In addition, calves can be separated into three types: (1) Type I which never demonstrates high EPG values, (2) Type II which shows rises in EPG values through the first 2 months on pasture which then fall and remain at levels associated with Type I calves, and (3) Type III calves which maintain high EPG levels. The approximate percentage of these calves is 25:50:25 respectively. Because these cattle are segregating for traits involved in resistance and susceptibility to GI nematodes, this resource population is being used to effectively detect the genomic locations of these Economic Trait Loci (ETL). For relational analysis between phenotype and genome location, over 80,000 genotypes have been generated by PCR amplification, and marker genotypes have been scored to produce inheritance data. The marker allele inheritance data is currently being statistically analyzed to detect patterns of co-segregation between allele haplotype and EPG phenotypes. Statistical power of this genome-wide scan has been strengthened by including genotypic data from the historic pedigree. In our herd, paternal half-sib families range from 5-13 progeny/sire, and extensive marker genotypes are available from ancestors of the population most of which are paternally descended from a single founding sire. Once ETL have been identified the next will be to refine ETL map resolution in attempt to discover the genes underlying disease phenotypes. Accurate identification of genes controlling resistance will offer the producer several alternatives for disease control. For a non-organic producer, the small percentage of susceptible animals can be targeted for drug administration. This approach would reduce both the cost of anthelmintics used and the odds for selection of drug resistant mutants, because the selective agent (drug) would not be applied over the entire parasite population. A second treatment option would be based on correcting a heritable immunologic condition. In this case, susceptible animals could be the targets for immunotherapy involving vaccines of immunomodulation. A final option would be genetic selection to remove susceptible animals from the herd. Producers with a high degree of risk for parasite-induced production losses, such as organic producers of producers in geographic areas with environmental conditions favorable to high rates of transmission would benefit the most from this strategy. In contrast, producers at low risk could take a more conservative approach and select against susceptibility when other factors were equal.     

The effects of florfenicol on lymphocyte subsets and humoral immune response in mice

Florfenicol is a broad-spectrum bacteriostatic antibiotic used in domestic animals. The aim of the study was to determine the effect of florfenicol on the total number of lymphocytes in the thymus, spleen and mesenteric lymph nodes and the percentage and the absolute number of T cell subsets (CD4+CD8+, CD4-CD8-, CD4+, CD8+) in the thymus and T (CD3+, CD4+, CD8+) and B (CD19+) lymphocytes in the peripheral lymphatic organs in non-immunized mice and humoral immune response in sheep red blood cells (SRBC)-immunized mice. Florfenicol was administered orally at a dose of 30 mg/kg six times at 24 h intervals to non-immunized mice and four or seven times at 24 h intervals to SRBC-immunized mice. SRBC was injected 2 hours prior to the first dose of the drug. Florfenicol increased the percentage of CD4CD8- thymocytes and the absolute number of CD4+ and CD8+ thymocytes on day 7. The increased percentage and absolute number of CD3+, CD4+ and CD8+ lymphocytes in mesenteric lymph nodes and decreased percentage of lymphocytes B were also observed 24 hours from the last administration of florfenicol. Florfenicol administered after SRBC immunization reduced the number of plaque forming cells (PFC) and the production of anti-SRBC antibodies on days 4 and 7 after priming.     

Induction of systemic and mucosal immune response in cattle by intranasal administration of pig serum albumin in alginate microparticles

Biodegradable microparticles are an efficient mucosal delivery system that protect antigens from the harsh mucosal environment and facilitate their uptake by M cells at the epithelium of mucosal-associated lymphoid tissue. In this study, we determined the systemic and mucosal immune response in calves following intranasal and oral immunization with pig serum albumin (PSA) encapsulated in alginate microparticles. The size of the particles ranged from 1 to 50 microm in diameter, with 95% of the particles being smaller than 5 microm. High levels of anti-PSA IgG1 antibodies were found in the serum, nasal secretions, and to a less extent in saliva of calves vaccinated intranasally, but not orally, with PSA-microparticles. There was no significant increase of PSA-specific IgA. A weak lymphocyte proliferative immune response was observed in peripheral blood mononuclear cells (PBMCs), and few anti-PSA antibody-secreting cells (ASC) were detected in the blood of calves immunized intranasally. The combined systemic and mucosal response observed in intranasally immunized animals may be attributed to the wide variation in the size of the alginate microparticles, with smaller particles translocating to regional lymph nodes and inducing a systemic immune response, and larger particles being retained in the NALT and inducing a mucosal immune response. The procedure presented here may be useful as an intranasal vaccine against respiratory diseases in cattle.     

Humoral and cell-mediated immune responses of d/d histocompatible pigs against classical swine fever (CSF) virus

A better understanding of cell-mediated immune responses to classical swine fever virus (CSFV) is essential for the future development of improved vaccines. We analyzed the generation of cell-mediated and humoral immune responses in d/d histocompatible pigs following CSFV infection or vaccination. Viral infection induced high T cell responses with high primary and secondary CTL activity correlated with high IFN-gamma production, whereas vaccination with a live vaccine followed by infection mainly induced neutralizing antibody but low cell-mediated responses. Moreover, high IgG1 response was associated with high IFN-gamma response following infection whereas a weak IFN-gamma response was related to a good IgG2 response but a low IgG1 production. These data could reflect Th1/Th2-like balance of immune responses depending upon immunization protocols, which has not yet been described in the pig. T-cell responses to CSFV were evidenced by CSFV-specific CD25 upregulation on CD4-CD8+, but not on CD4+CD8- cells, which further illustrated the importance of CTL responses after infection. Our results indicated that generation of cell-mediated immune responses was much higher following intranasal/oral CSFV infection than after intramuscular vaccination, which implies that the capacity of new CSFV vaccines to induce higher T-cell responses should be considered.     

Evaluation of a specific immunochemotherapy for the treatment of canine visceral leishmaniasis

The efficacy of specific immunochemotherapy against Leishmania infantum infection in dog was studied. The effects on transmission of the disease, as well as the cellular and humoral immune response were examined. The treated animals showed a significant reduction in the infection rates that were detected in Phlebotomus perniciosus females fed on the dog. The humoral immune response, assayed with an indirect immunofluorescence antibody test (IFAT), did not show significant variations under the influence of the therapy. The characterisation of the peripheral blood mononuclear cells (PBMC) using flow cytometry indicated a significant increase in the proportion of T lymphocytes, especially of CD4/TcR(alpha)(beta)(+) and CD4/CD45RA(+) cells, without showing evidence for modifications in the other leukocyte subsets. Cellular lymphoproliferation studies indicated a lack of a specific response to soluble leishmanial antigen (SLA), but the non-specific lymphoproliferative capacity assayed with phytohemagglutinin (PHA) was maintained.     

Identification of immune response correlates for protection against bovine tuberculosis

Identification of an immune response correlate for protection against bovine tuberculosis would greatly facilitate the rational development of an effective vaccine. However, finding such a correlate has been a daunting task. Vaccination/challenge studies in cattle provide an ideal platform to compare induction of immune response parameters following vaccination and challenge, and assess the correlation of these parameters with protection. Protection against tuberculosis requires a Th 1-type cell-mediated immune response and induction of an antigen-specific interferon-gamma (IFN-gamma) response was the logical first choice in an investigation to identify an immune response correlate for protection. Calf vaccination studies showed that the subcutaneous injection of BCG vaccine induced significant protection against experimental challenge with Mycobacterium bovis. This protection was associated with strong whole blood IFN-gamma responses to bovine PPD 2-4 weeks after vaccination, but within the BCG-vaccinated groups, these responses were not correlated with protection. Use of a variety of vaccination strategies has shown that IFN-gamma responses in isolation were not necessarily associated with protection and concurrent IL-4 mRNA expression or antibody responses could also be induced. Collation of an immunological profile may be more informative than a study of individual cytokines. An indication of vaccine efficacy can be provided by the study of immune responses following challenge of the calves with M. bovis. IFN-gamma responses to ESAT-6, antibody responses following tuberculin skin testing and antigen-specific IL-4 mRNA expression all correlated with the severity of disease and indirectly provided an indication of protection. Future studies should be directed towards obtaining immunological profiles of calves following vaccination using techniques such as DNA microarray analysis, measurement of cytokine mRNA expression by real-time PCR, protein profiling by SELDI-TOF mass spectrometry as well as determining cytokine production by specific T cell sub-sets in individual protected animals.     

Membrane markers of the immune cells in swine: an update

Besides their breeding value, swine are increasingly used as biomedical models. As reported in three international swine clusters of differentiation (CD) workshops and in the animal homologue section of the last workshop for the determination of human leukocyte differentiation antigens (HLDA 8), characterisation of leukocyte surface antigens by monoclonal antibodies and other molecular studies have determined the cell lineages and blood leukocyte subsets implicated in the immune response, including cell adhesion molecules involved in cell trafficking. This review focusses on the current state of knowledge of porcine leukocyte differentiation and major histocompatibility complex (SLA) molecules. Examples of porcine particularities such as the double-positive T lymphocytes with the phenotype CD(4+)CD8(low) and CD(4-)CD8(low) alphabeta T cell subsets and the persistence of SLA class II after T-lymphocyte activation are illustrated, as well as the shared characteristics of the Artiodactyla group, such as the high proportion of gammadelta TcR (T cell receptor) T cells in blood and other lymphoid tissues. Furthermore, discrepancies between swine and humans, such as CD16 expression on dendritic cells and CD11b (wCD11R1) tissue distribution are outlined. The rapidly growing information should facilitate manipulation of the swine immune system towards improving disease control, and open new avenues for biomedical research using the pig as a model.