Quantitation of canine regulatory T cell populations, serum interleukin-10 and allergen-specific IgE concentrations in healthy control dogs and canine atopic dermatitis patients receiving allergen-specific immunotherapy.

Canine atopic dermatitis (AD) shares many clinical and immunological similarities with human AD. Regulatory T cells (Treg) are a distinct lineage of T lymphocytes with various immunosuppressive properties including the down-regulation of allergic inflammation associated with IgE production. Antigen-induced Treg typically regulate immune homeostasis via productions of cytokines such as interleukin-10. Given the immunological similarities with human AD, it is likely that Tregs and the cytokines they produce play an important role in diseases of dogs as well. A cross-reactive FoxP3 antibody was used to identify a subset of CD4(+) T cells in the blood of both healthy dogs and dogs with atopic dermatitis undergoing immunotherapy over a year period. There was no significant difference in the Treg percentage over time in the healthy dogs. The immunotherapy group showed a significant increase in Treg percentage at 6, 9, and 12 months when compared to the healthy dogs. For the immunotherapy group, the mean Treg percentage at the beginning of the study was 4.94+/-0.71 and 10.86+/-2.73 at the completion. A commercially available ELISA kit was also used to quantitate the concentration of IL-10 in the serum of the same subsets of dogs. There was no significant difference in the IL-10 concentrations over time in the healthy dogs. The immunotherapy group showed a significant increase in serum IL-10 concentrations at 6, 9, and 12 months when compared to the control group. The mean serum IL-10 concentration at the initiation of immunotherapy was 20.40+/-3.52ngL(-1) and 37.26+/-15.26ngL(-1) at the completion of the study. The immunotherapy group also showed a significant decrease in serum IgE levels over the 1-year treatment period for specific allergens identified during ASIT. We conclude from these studies that similar to humans undergoing immunotherapy, increasing Treg populations likely play a significant role in the success of this particular type of therapy for atopic dermatitis and other allergic conditions.

Passive transfer of virus-specific antibodies confers protection against reproductive failure induced by a virulent strain of porcine reproductive and respiratory syndrome virus and establishes sterilizing immunity.

Immune mechanisms mediating protective immunity against porcine reproductive and respiratory syndrome virus (PRRSV) are not well understood. The PRRSV-specific humoral immune response has been dismissed as being ineffective and perhaps deleterious for the host. The function of PRRSV antibodies in protective immunity against infection with a highly abortifacient strain of this virus was examined by passive transfer experiments in pregnant swine. All of a group of pregnant gilts (n = 6) that received PRRSV immunoglobulin (Ig) from PRRSV-convalescent, hyperimmune animals were fully protected from reproductive failure as judged by 95% viability of offspring at weaning (15 days of age). On the other hand, the totality of animals in a matched control group (n = 6) receiving anti-pseudorabies virus (PRV) Ig exhibited marked reproductive failure with 4% survival at weaning. Besides protecting the pregnant females from clinical reproductive disease, the passive transfer of PRRSV Ig prevented the challenge virus from infecting the dams and precluded its vertical transmission, as evidenced by the complete absence of infectious PRRSV from the tissues of the dams and lack of infection in their offspring. In summary, these results indicate that PRRSV-Igs are capable of conferring protective immunity against PRRSV and furthermore that these Igs can provide sterilizing immunity in vivo.

Overview of the Third International Workshop on Swine Leukocyte Differentiation Antigens.

The aim of the Third International Workshop on Swine Leukocyte Differentiation Antigens (CD workshop), supported by the Veterinary Immunology Committee (VIC) of the International Union of Immunological Societies (IUIS), was to standardize the assignment of monoclonal antibodies (mAb) reactive with porcine leukocyte differentiation antigens and to define new antibody clusters, using nomenclature in accordance with human and ruminant CD nomenclature, as agreed at the summary meeting of the Second International Swine CD Workshop in Davis, 1995: only mAb with proven reactivity for the orthologous porcine gene product or cross-reactivity for the human gene products, were given the full CD nomenclature, all other allocations were prefixed with "w". As in previous workshops, the overall organization was entrusted to the chair and first author, with support by the chair of the previous workshop and second author. In addition to the existing 26 pig leukocyte CD/SWC determinants established in previous workshops, this workshop established/confirmed another 11 CDs for pig leukocytes, identified by a total of 21 mAb: CD11R1 (2 mAb), CD11R2 (1 mAb), CD11R3 (4 mAb), wCD40 (1 mAb), wCD46 (4 mAb), wCD47 (3 mAb), wCD49d (1 mAb), CD61 (1 mAb), wCD92 (1 mAb), wCD93 (1 mAb) and CD163 (2 mAb).

Summary of workshop findings for porcine T-lymphocyte-specific monoclonal antibodies.

Fifty-seven monoclonal antibodies (mAb) selected after the first round analyses in the Third International Swine CD workshop for their possible reactivity with T-lymphocyte specific antigens were further analysed in a second round. As target cells for flow cytometric analyses served peripheral blood mononuclear cells, nylon-wool enriched T-lymphocytes, thymocytes, splenocytes, and lymphocytes derived from Peyer's patches. These second round analyses revealed 15 different data sets. Together with 22 pre-selected data sets from the first round analyses with the whole panel of monoclonal antibodies, 37 data sets were used for the clustering of the respective mAb. Using the LTDB4 program, 19 preliminary clusters could be defined. Two clusters (C3 and C7) with 4 mAb showed no labelling of resting T-lymphocytes. Seven clusters (C1, C2, C4, C5, C6, C11, and C12) contain mAb (in total: 16 mAb) directed against subsets of CD4(-)CD8(-) T-lymphocytes. These mAb seem to recognise antigens on porcine T-lymphocytes with T-cell receptor (TcR) gamma/delta chains. Three clusters (C8, C9, C10, C13) seem to be artificial. They contain either mAb staining CD4(-)CD8(-) T-lymphocytes and low CD8+ cells (C8, C9), mAb with various reactivity (C10) and mAb with known differences in their reactivity (C13). Cluster C14 contains 3 mAb against the CD4a-epitope, C15 describes mAb directed against porcine CD8c-epitope whereas mAb against CD8a and CD8b-epitopes grouped in C19. The mAb found in C16 seem to recognise CD45R. Cluster C17 is composed of different standards directed against CD2, CD3, CD5 and wCD6. Two additional mAb recognising the CD2a-epitope could be enclosed. C18 contains two mAb directed against SWC2.

Characterization of monoclonal antibodies assigned to the CD45 subgroup of the Third International Swine CD Workshop.

As a result of the first-round cluster analysis, a panel of 16 novel monoclonal antibodies (mAbs) was assigned for detailed analysis to the CD45 subgroup of the Third International Swine CD Workshop. The specificity of the mAbs was initially determined by examining their reactivity with Chinese hamster ovary (CHO) cells engineered to express individual isoforms of porcine CD45. These analyses indicated that seven of the mAbs (PG77A, PG96A, PG167A, PGB78A, 3C/9, MIL13, NHT 101) recognized the portion of the CD45 molecule encoded by the A exon (CD45RA), while one (MIL15) was specific for that portion encoded by the C exon (CD45RC). In each case, the designation was supported by the demonstration that the molecular weight(s) of the recognized antigen(s) in porcine mononuclear cells, as determined by immunoprecipitation, corresponded to the predicted size(s) according to their specificity. As expected, a similar correlation was obtained for five standard mAbs whose specificity for either common or restricted epitopes of porcine CD45 had been established in previous workshops. Screening of the remaining 174 mAbs that comprised this workshop but were excluded from the CD45 subgroup by cluster analysis failed to detect any additional ones reactive with the porcine CD45-expressing cells.

Antigen-specific proliferation of porcine CD8alphaalpha cells to an extracellular bacterial pathogen.

A vaccine inducing protective immunity to a spirochaete-induced colitis of pigs predominantly stimulates expansion of CD8+ cells in vivo and in antigen-stimulated lymphocyte cultures. CD8+ cells, however, are rarely considered necessary for protection against extracellular bacterial pathogens. In the present study, pigs recovering from colitis resulting from experimental infection with Brachyspira (Serpulina) hyodysenteriae had increased percentages of peripheral blood CD4- CD8+ (alphaalpha-expressing) cells compared with non-infected pigs. CD8alphaalpha+ cells proliferated in antigen-stimulated cultures of peripheral blood mononuclear cells from B. hyodysenteriae-vaccinated pigs. Proliferating CD8alphaalpha+ cells consisted of CD4-, CD4+ and gammadelta T-cell receptor-positive cells. CD4- CD8alphabeta+ cells from vaccinated or infected pigs did not proliferate upon in vitro antigen stimulation. Of the CD8alphaalpha cells that had proliferated, flow cytometric analysis indicated that the majority of the CD4+ CD8+ cells were large (i.e. lymphoblasts) whereas the CD4- CD8+ cells were predominantly small. Addition of monoclonal antibodies (mAb) specific for either porcine major histocompatibility complex (MHC) class I or class II antigens diminished B. hyodysenteriae-specific proliferative responses whereas addition of mAb to porcine MHC II, but not porcine MHC I, reduced the CD8alphaalpha response. In vitro depletion of CD4+ cells by flow cytometric cell sorting diminished, but did not completely abrogate, the proliferative response of cells from vaccinated pigs to B. hyodysenteriae antigen stimulation. These results suggest that CD8alphaalpha cells are involved in recovery and possibly protection from a spirochaete-induced colitis of pigs; yet, this response appears to be partially dependent upon CD4+ cells.

Reduction in inflammation following blockade of CD18 or CD29 adhesive pathways during the acute phase of a spirochetal-induced colitis in mice.

Colitis develops in mice infected with Brachyspira (Serpulina) hyodysenteriae. Numerous granulocytes (PMNs) are evident in cecal tissue sections 24-48 h post-infection. The role of PMNs was assessed by utilizing monoclonal antibodies specific for CD18 or CD29 to block PMN recruitment. Macroscopic lesions were less severe in mice treated with either monoclonal antibody compared to lesions observed in isotype control-treated mice. While these monoclonal antibodies may inhibit extravasation of other leukocytes, the central role of PMNs was further demonstrated in that colitis was reduced following neutrophil depletion. There was less edema and epithelial erosions in ceca of mice receiving anti-Ly6G, -CD18 or -CD29 monoclonal antibody compared to mice receiving the control. Moreover, there was a significant reduction in PMN infiltration in tissues of mice treated with anti-CD18. The reduction in infiltrating PMNs did not result from downregulation of neutrophil chemoattractant MIP-2 expression in anti-CD18-treated mice. In contrast, PMN recruitment into the cecum was apparently CD29-independent. It is noteworthy that the number of PMNs observed in anti-CD18-treated mice was significantly higher than observed in non-infected mice. The data provide evidence for a threshold number of PMNs necessary for lesion development and indicate that CD18, but not CD29, adhesive pathways are crucial for PMN recruitment in bacterial colitis.

Systemic and mucosal immune responses to H1N1 influenza virus infection in pigs.

Influenza is a common respiratory disease in pigs, and since swine influenza viruses are zoonotic pathogens, they also pose human health risks. Pigs infected with influenza virus mount an effective immune response and are protected from subsequent challenge, whereas the currently available, inactivated-virus vaccine does not consistently confer complete protection to challenge. To develop and evaluate new vaccination strategies, it is imperative to fully understand the immune responses that are associated with protection following natural infection. Therefore, we have evaluated the phenotype and kinetics of immune responses to primary and re-challenge infection with H1N1 swine influenza virus in the pig. Through the use of isotype-specific antibody secreting cell ELISPOT assays, interferon-gamma ELISPOT assays and isotype-specific ELISAs on serum, nasal wash and bronchoalveolar lavage samples, we defined the humoral and cellular immune responses, both locally in the respiratory tract and systemically, to this viral infection. Virus-specific serum IgG, IgA, and HI titers all peaked 2-3 weeks after primary infection and did not substantially increase after re-challenge. The predominant virus-specific isotype in serum was IgG. Pigs responded with virus-specific IgG and IgA in both the upper (nasal washes) and lower (bronchoalveolar lavages) airways; IgA was the predominant isotype in both sites. Despite the fact that the pigs were completely protected from re-challenge, the antibody titers in the nasal washes increased. Results of the antibody-secreting cell ELISPOT assays demonstrated that the numbers of both IgG and IgA secreting cells in the nasal mucosa were dramatically higher than in any other tissue examined. In contrast, IFN-gamma secreting cells were predominantly localized to the spleen and tracheobronchial lymph nodes. These data will be helpful in the future development and evaluation of novel vaccines.

Aujeszky's disease virus: opportunities and challenges.

Since its description in 1902, Aujeszky's disease (AD) has become one of the most thoroughly examined viral diseases of swine. The causative agent, Aujeszky's disease virus (ADV), is a neurotropic alphaherpesvirus that produces fatal encephalitis in newborn pigs and a milder syndrome in older animals. In several instances this virus has been used as a test case to examine novel vaccine concepts in swine, including the honor of being the first genetically modified vaccine used in the field. Furthermore, the examination of the immune response to infection or vaccination with this virus has revealed important information about the function of the porcine immune system, including evidence on the existence of a dichotomy between the humoral and cellular immune response in swine. This review presents a summary of research where ADV has been a valuable tool for the development of novel vaccines and has provided information to better understand the immune response of swine to infectious agents.

Extrathymic CD4/CD8 double positive T cells.

Mature T lymphocytes expressing the alphabeta T cell receptor are generally classified as either CD4+ or CD8+, based on the mutually exclusive expression of these two lymphocyte coreceptors. Contrary to this conventional division, there is considerable evidence that significant numbers of CD4/CD8 double positive (DP) lymphocytes exist in the peripheral blood and secondary lymphoid tissues of swine, chickens and monkeys. Although CD4/CD8 DP T cells are rarely present in human peripheral blood the relative percentage of this lymphocyte population can increase spontaneously in healthy individuals and in persons suffering from certain disease conditions. DP can also be found among those T cells infiltrating arthritic joints, rejected kidney grafts and certain tumors. In humans, and rats, CD4/CD8 DP T cells appear transiently following activation of their progenitors. Murine DP cells have been described as a subset of intraepithelial lymphocytes (IELs). However, the relationship of IELs to DP cells in the peripheral blood of other species is unknown. Because of their unconventional phenotype and rarity in human and mice, most immunologists have ignored extrathymic CD4/CD8 DP lymphocytes. Nevertheless, their abundance in the peripheral blood of swine, monkeys and chickens makes it impossible to dismiss this lymphocyte population. Here are reports that have described extrathymic lymphocytes exhibiting a CD4+CD8dim phenotype in several species reviewed. Swine and monkey lymphocytes with this phenotype are represented by small resting cells that simultaneously express CD4 and CD8alpha molecules. The available evidence favors the notion that such DP T cells in swine are comprised predominantly of MHC class II restricted memory CD4+ helper T cells that after activation have acquired the ability to express the CD8alpha chain and then to maintain this DP phenotype. Moreover, porcine CD4/CD8 DP T cells appear to be comprised of memory cells due to their ability to respond to recall antigen, resilience to thymectomy, increase in proportion with age, expression of memory T cell markers, production of interferon-gamma and localization to inflammatory sites. Some of these characteristics are also descriptive of human and monkey CD4/CD8 DP T cells. Thus, in swine, humans and monkeys, these phenotypically distinct lymphocytes appear to represent a primed T cell subset. The possible functional significance of the simultaneous expression of the CD4 and CD8 co-receptors on mature T cells is discussed.

Total parenteral nutrition alters molecular and cellular indices of intestinal inflammation in neonatal piglets.

BACKGROUND: The adverse effects of TPN on systemic immunity are well-documented; however, the impact of IV feeding on neonatal intestinal immunity is unknown. METHODS: A piglet TPN model was used to compare immune cell composition within the intestinal epithelium and lamina propria of parenterally and orally fed piglets. RESULTS: Small intestinal weight of piglets maintained intravenously was reduced 50% after 7 days. Intestinal atrophy in piglets fed parenterally was evidenced by decreased width of intestinal villi and colon cuffs and reduced intestinal crypt depth. The numbers of CD4+ and CD8+ T lymphocytes were threefold greater within the lamina propria of jejunal and ileal villi of piglets supported intravenously. Inverse correlations were observed between villus height or width and T-lymphocyte numbers (r = -.80; p < .05). Major histocompatibility complex class II mRNA expression, an indicator of localized inflammation, was increased in the ileum and colon of piglets receiving parenteral nutrition. Goblet cell numbers were two-fold greater in jejunal and ileal villi, and mast cells were more abundant in the colon of piglets fed parenterally. Furthermore, jejunal T-lymphocyte numbers were correlated with goblet cell numbers (r = .80; p = .01). CONCLUSIONS: These data identify molecular and cellular indices of intestinal inflammation that are responsive to IV feeding in neonates and provide a novel framework to investigate mechanisms underlying gut atrophy during TPN.

Cellular immune responses of pigs induced by vaccination with either a whole cell sonicate or pepsin-digested Brachyspira (Serpulina) hyodysenteriae bacterin.

Brachyspira (Serpulina) hyodysenteriae infection of pigs (swine dysentery) causes a mucohemorrhagic diarrhea resulting in significant economic losses for producers. A commercial vaccine consisting of a proteinase-digested bacterin has shown efficacy in the reduction of disease due to B. hyodysenteriae. Vaccines consisting of whole cell bacterins, however, generally fail to protect pigs from disease. In the present study, cellular immune responses induced by a proteinase-digested bacterin were compared to responses induced by a whole cell sonicate antigen preparation. In addition, usage of either squalene or Freund's incomplete adjuvants in combination with each antigen preparation was also compared. Both antigen preparations induced significant cellular immune responses as measured by in vitro (IFN-gamma production and T cell proliferation) and in vivo methods (DTH responses). No significant differences were detected in proliferative, interferon-gamma (IFN-gamma), or delayed type hypersensitivity (DTH) responses by pigs receiving either adjuvant or antigen preparation. T cells (CD3(+)) but not B cells from vaccinated animals proliferated in response to in vitro stimulation with B. hyodysenteriae antigen. CD8(+) (single positive and CD4/CD8 double positive) and gammadelta(+) T cells were particularly responsive. In addition, high percentages of both CD8 single positive and CD4/CD8 double positive cells were detected in antigen-stimulated cultures. These findings demonstrate the unique sensitivity of porcine CD8(+) T cells to priming for recall response by vaccination with a proteinase-digested B. hyodysenteriae bacterin.

Systemic and mucosal immune responses of pigs to parenteral immunization with a pepsin-digested Serpulina hyodysenteriae bacterin.

Serpulina hyodysenteriae infection of pigs, swine dysentery, causes a mucohemorrhagic diarrhoea resulting in significant economic losses to swine producers. The pathogenesis of this disease is poorly understood. Regardless, commercial vaccines have been developed and are in use. Thus, the present study was designed to examine cellular immune responses induced by parenteral S. hyodysenteriae vaccination. Significant antigen-specific interferon-gamma (IFN-gamma) and blastogenic responses were detected from peripheral blood lymphocytes isolated from vaccinated pigs. However, poor IFN-gamma responses were detected from colonic lymph node lymphocytes from these same pigs despite significant antigen-specific blastogenic responses. In addition, peripheral blood IFN-gamma responses were diminished by either in vitro depletion of CD4 expressing cells or by in vitro treatment with porcine IL-10. Colonic lymph node IFN-gamma responses were not inhibited by treatment with porcine IL-10. Vaccination also resulted in increased percentages of both mucosal and peripheral blood CD8 single positive cells with concurrent decreases in percentages of CD4 single positive cells as compared to percentages of these same populations from non-vaccinated pigs. In conclusion, these studies show that parenteral S. hyodysenteriae vaccination results in cellular immune responses detectable both peripherally (systemic immunity) as well as at the site of infection (mucosal immunity). However, it appears that regulatory mechanisms affecting IFN-gamma production in response to S. hyodysenteriae antigen differ between peripheral and colonic compartments.

Effect of transportation and feed withdrawal on shedding of Salmonella typhimurium among experimentally infected pigs.

OBJECTIVE: To determine whether stress associated with transportation or feed withdrawal increased fecal shedding of Salmonella Typhimurium among pigs experimentally infected with the organism. ANIMALS: 86 healthy pigs. PROCEDURE: Pigs were challenge exposed with Salmonella Typhimurium at 4 weeks old and reared conventionally. When pigs reached market weight, they were assigned to groups and subjected to various combinations of transportation and feed withdrawal. Ileocecal contents were collected after slaughter and tested for Salmonella Typhimurium. RESULTS: Salmonella Typhimurium was not detected in feces collected from pigs just prior to slaughter. When feed was withheld for 24 hours prior to slaughter, the proportion of transported pigs with Salmonella Typhimurium in ileocecal contents at the time of slaughter was not significantly different from the proportion of nontransported pigs. However, when feed was not withheld prior to slaughter, the proportion of transported pigs with Salmonella Typhimurium in ileocecal contents at the time of slaughter was significantly higher than the proportion of nontransported pigs. CONCLUSIONS AND CLINICAL RELEVANCE: When carrier pigs remained on feed, transportation stress increased the proportion positive for Salmonella sp. On the basis of results reported here, it is suggested that producers withhold feed from pigs for 24 hours prior to transportation to a slaughter plant.

Antibody and cellular immune responses of swine following immunisation with plasmid DNA encoding the PRRS virus ORF's 4, 5, 6 and 7.

The objectives of this study was to investigate the role of DNA vaccines in the generation of an immune response and that elicited against individually encoded proteins of PRRSV. The genomic regions encoding ORF s 4, 5, 6 and 7 of the PRRS virus vaccine strain were cloned into the mammalian expression vector pc DNA 3.1 (+). Inoculations with the recombinant plasmids resulted in detection of PRRS virus-specific antibodies in 71 per cent of the immunized animals by ELISA, virus neutralization and/or Western blotting assays. In addition, cellular immune responses were detected in 86 per cent of the immunized pigs by interferon gamma assay and/or proliferation assay. Pigs in the control group had no detectable immune response to PRRS virus. The results obtained demonstrated that DNA immunization against PRRS virus results in the production of both humoral and cell mediated immune responses in pigs. The results also indicate that neutralization epitopes for PRRS virus are present on the viral envelope glycoproteins encoded by ORF 4 and ORF 5.

Molecular cloning and characterization of a novel CD1 gene from the pig.

Much effort is underway to define the immunological functions of the CD1 multigene family, which encodes a separate lineage of Ag presentation molecules capable of presenting lipid and glycolipid Ags. To identify porcine CD1 homologues, a cosmid library was constructed and screened with a degenerate CD1 alpha3 domain probe. One porcine CD1 gene (pCD1.1) was isolated and fully characterized. The pCD1.1 gene is organized similarly to MHC class I and other CD1 genes and contains an open reading frame of 1020 bp encoding 339 amino acids. Expression of pCD1.1 mRNA was observed in CD3- thymocytes, B lymphocytes, and tissue macrophages and dendritic cells. The pCD1.1 cDNA was transfected into Chinese hamster ovary cells, and subsequent FACS analysis demonstrated that mAb 76-7-4, previously suggested to be a pig CD1 mAb, recognizes cell surface pCD1.1. Structurally, the pCD1.1 alpha1 and alpha2 domains are relatively dissimilar to those of other CD1 molecules, whereas the alpha3 domain is conserved. Overall, pCD1.1 bears the highest similarity with human CD1a, and the ectodomain sequences characteristically encode a hydrophobic Ag-binding pocket. Distinct from other CD1 molecules, pCD1.1 contains a putative serine phosphorylation motif similar to that found in human, pig, and mouse MHC class Ia molecules and to that found in rodent, but not human, MHC class-I related (MR1) cytoplasmic tail sequences. Thus, pCD1.1 encodes a molecule with a conventional CD1 ectodomain and an MHC class I-like cytoplasmic tail. The unique features of pCD1.1 provoke intriguing questions about the immunologic functions of CD1 and the evolution of Ag presentation gene families.

Malnutrition modifies pig small intestinal inflammatory responses to rotavirus.

Infectious diarrheal diseases and malnutrition are major causes of child morbidity and mortality. In this study, malnutrition was superimposed on rotavirus infection in neonatal piglets to simulate the combined intestinal stress of viral enteritis in malnourished infants. Two-day-old piglets were assigned to three treatment groups as follows: 1) noninfected, fully nourished; 2) infected, fully nourished; and 3) infected, malnourished. Intestinal indices of inflammation were monitored over the subsequent 2-wk period. Intestinal damage and diarrhea were observed within 2 d of rotavirus infection and began to subside in nourished piglets by d 9 but persisted through d 16 postinfection in malnourished piglets. Rotavirus upregulated small intestinal expression of major histocompatibility complex (MHC) class I and class II genes; malnutrition intensified MHC class I gene expression and suppressed MHC class II expression. Jejunal CD4(+) and CD8(+) T-lymphocyte numbers were elevated for infected, nourished piglets on d 2, 9 and 16 postinfection. Malnutrition did not significantly affect the local expansion of T cell subsets in response to rotavirus. Intestinal prostaglandin E2 (PGE2) concentrations were elevated early after rotavirus infection independent of nutritional state. By d 9, PGE2 concentrations returned to baseline in infected, nourished piglets but remained elevated in malnourished piglets, corresponding to diarrhea observations. Together, the results identify intestinal indices of inflammation that are modulated by malnutrition and prompt reconsideration of current models of rotavirus pathophysiology.

Weaning anorexia may contribute to local inflammation in the piglet small intestine.

Compromising alterations in villus-crypt structure are common in pigs postweaning. Possible contributions of local inflammatory reactions to villus-crypt alterations during the weaning transition have not been described. This study evaluated local inflammatory responses and their relationship with morphological changes in the intestine in 21-d-old pigs (n = 112) killed either at weaning (Day 0) or 0.5, 1, 2, 4 or 7 d after weaning to either milk- or soy-based pelleted diets. Cumulative intake averaged <100 g during the first 2 d postweaning, regardless of diet. During this period of weaning anorexia, inflammatory T-cell numbers and local expression of the matrix metalloproteinase stromelysin increased while jejunal villus height, crypt depth and major histocompatibility complex (MHC) class I RNA expression decreased. Upon resumption of feed intake by the fourth d postweaning, villus height and crypt depth, CD8(+) T cell numbers, MHC class I RNA expression and local expression of stromelysin returned to Day 0 values. Together the results indicate that inadequate feed intake during the immediate postweaning period may contribute to intestinal inflammation and thereby compromise villus-crypt structure and function.

Use of interleukin 12 to enhance the cellular immune response of swine to an inactivated herpesvirus vaccine.

Vaccination is the single most successful medical measure against infectious disease. However, the major barrier for achieving the full protective effect or immunization is how to render attenuated, killed, or subunit vaccines as immunogenic as the fully infectious versions of these microbes (Hughes and Babiuk, 1995; Rabinovich et al., 1994). In the case of PrV, infection with wild-type virus induces an immune response superior to vaccination with a live modified vaccine. After primary intranasal infection with wild-type PrV, the replication of a homologous secondary virus challenge is completely inhibited, and the much sought "sterile immunity" is generated (Kimman et al., 1994). In contrast, the immune response of pigs similarly exposed to PrV mutants, which have been attenuated by removal of the thymidine kinase (TK) and the envelope glycoprotein gE gene (McGregor et al., 1985; Zuckermann et al., 1988), is insufficient for preventing the replication of a homologous wild-type virus challenge (Kimman et al., 1994). Furthermore, inactivated PrV vaccines are even less effective at inducing protective immunity than are live modified PrV vaccines (de Leeuw and Van Orischot, 1985; Stellman et al., 1989; Vannier, 1985). The importance of inactivated and subunit vaccines resides in their stability and safety, since no infectious microbe is being introduced into the animal. However, because of the recognized lower effectiveness of inactivated vaccine types, they usually fall in disfavor when a modified live vaccine alternative is available. There is a critical need to develop strategies to enhance the immunogenicity of live, inactivated, and sub-unit vaccines for human and veterinary use (Hughes and Babiuk, 1995; Rabinovich et al., 1994). Although the inoculation of an animal with a virulent microbe is obviously not the desired method to produce sterile immunity, the immune response generated to infection with wild-type PrV clearly demonstrates that this type of immunity is possible. Research directed at devising strategies to increase the immunogenicity of different types of vaccines is necessary. Because of the wealth of information available on PrV immunity (reviewed by Chinsakchai and Molitor, 1994; Nauwynck, 1997), on PrV vaccines (Kimman et al., 1992, 1994; Mettenleiter, 1991; Scherba and Zuckermann, 1996) and increasingly on the porcine immune system (Lunney, 1993; Lunney et al., 1996; Saalmüller, 1995), the swine herpesvirus model is ideal for investigating the development of vaccine formulations with enhanced immunogenicity. Among the strategies currently being examined for the enhancement of the immunogenicity of inactivated and subunit vaccines is the use of recombinant cytokines administered together with antigen (Hughes and Babiuk, 1995; Rabinovich et al., 1994). The ability to regulate the development of an immune response by cytokines such as IL-12 provides the theoretical basis to use these cytokines as adjuvants to immunopotentiate the response to an inactivated vaccine. More importantly, it provides a model to investigate the mechanisms behind the induction of protective immunity and the components of a vaccine necessary for stimulating such a response. By providing cytokines such as IL-12 or IFN-gamma in combination with the vaccine inoculum, it is reasonable to expect that they will be able to direct the differentiation of T cells during the primary immune response. Modulation, in a predictable and desired manner of the quality and quantity of the induced protective immunity, should be achievable. The ability to manipulate a vaccine-induced immune response in the direction of a predominantly cellular response (Th1-like) instead of a predominantly humoral one (Th2-like) is perhaps best illustrated by the need to develop an effective vaccine against the porcine reproductive and respiratory syndrome (PRRS) virus, whose infectivity can be significantly enhanced in vitro and in vivo by antibody induced by vaccination

Analysis of the immunological cross reactivities of 213 well characterized monoclonal antibodies with specificities against various leucocyte surface antigens of human and 11 animal species.

213 Monoclonal antibodies (mAbs) raised against leucocyte surface antigens from human and 11 animal species were analyzed for reactivities against leucocytes from human and 15 different animal species. We found 77 mAbs (36%) to cross-react. Altogether, 217 cross reactions were registered out of 3195 possible combinations (7%). Most of the cross reacting mAbs had integrin or MHC class II specificities. This study defined cross reactions on the following markers: CD1a, 1c, 2, 4, 5, 8, 9, 11a, 11b, 14, 18, 20, 21, 23, 29, 31, 41, 43, 44, 45, 45R, 46, 49, 61, 62L, TCR gamma/delta, BCR, Thy-1, MHC class I and MHC class II, Swine-WC7 and Cattle-WC1. In order to characterize the molecular weight (MW) of the corresponding cross reacting antigens, selected mAbs were used to immunoprecipitate the antigens. The MW's of the analyzed precipitated antigens were in good agreement with the MWs of the homologous antigens. The followed strategy was found to be efficient and economical in defining new leucocyte antigen reactive mAbs.