Physiological responses of feedlot heifers provided access to different levels of shade.

Heat stress has a significant impact on all livestock and poultry species causing economic losses and animal well-being concerns. Providing shade is one heat-abatement strategy that has been studied for years. Material selected to provide shade for animals greatly influences the overall stress reduction provided by shade. A study was conducted to quantify both the environment and animal response, when cattle had no shade access during summertime exposure or were given access to shade provided by three different materials. A total of 32 Black Angus heifers were assigned to one of the four treatment pens according to weight (eight animals per pen). Each pen was assigned a shade treatment: No Shade, Snow Fence, 60% Aluminet Shade Cloth and 100% Shade Cloth. In the shaded treatment pens, the shade structure covered ~40% of the pen (7.5 m2/animal). Animals were moved to a different treatment every 2 weeks in a 4×4 Latin square design to ensure each treatment was applied to each group of animals. Both environmental parameters and physiological responses were measured during the experiment. Environmental parameters included dry-bulb temperature, relative humidity, wind speed, black globe temperature (BGT), solar radiation (SR) and feedlot surface temperature. Animal response measurements included manual respiration rate (RRm), electronic respiration rate (RRe), vaginal temperature (body temperature (BT)), complete blood count (CBC) and plasma cortisol. The environmental data demonstrated changes proportional to the quality of shade offered. However, the animal responses did not follow this same trend. Some of the data suggest that any amount of shade was beneficial to the animals. However, Snow Fence may not offer adequate protection to reduce BT. For some of the parameters (BT, CBC and cortisol), 60% Aluminet and 100% Shade Cloth offers similar protection. The 60% Aluminet lowered RRe the most during extreme conditions. When considering all parameters, environmental and physiological, 60% Aluminet Shade Cloth offered reductions of BGT, SR, feedlot surface temperature and the best (or equal to the best) overall protection for the animals (RRe, RRm, BT, blood parameters).

Incidence of infection in 39-month-old ewes with TMEM154 diplotypes "1 1," "1 3," and "3 3" after natural exposure to ovine progressive pneumonia virus.

Production and well-being of sheep and goats in many countries are harmfully impacted by small ruminant lentiviruses (SRLV) that cause incurable, progressive diseases. Susceptibility to ovine progressive pneumonia virus (OPPV), the North American form of SRLV, is influenced by variants of the ovine transmembrane protein 154 gene (TMEM154). The experimental objective was to estimate additive and dominance effects of TMEM154 haplotypes 1 and 3 on susceptibility of breeding ewes to infection after natural exposure to OPPV from birth to 39 mo of age. Sires and dams were heterozygous for TMEM154 haplotypes 1 and 3, producing ewe lambs with diplotypes "1 1," "1 3," and "3 3." These lambs were raised by mature, infected dams to ensure natural, maternal exposure to OPPV. Ewe lambs (n = 108) were kept for breeding and joined an infected flock of ewes to guarantee natural, nonmaternal exposure to OPPV. Ewes were bred to lamb at 1, 2, and 3 yr of age. Serum samples were collected at breeding, 1 mo before lambing and shortly after weaning each year to monitor infection status to 39 mo of age. During the experiment, 9 of the 108 ewes died while uninfected and data collected on these ewes were not analyzed. Infection status of the remaining 99 ewes at 39 mo of age was analyzed using logistic regression procedures. Effects of ewe type of birth, ewe type of rearing, and breed type of dam were not detected (P > 0.10), and the estimated sire variance component was nil. Ewe diplotype affected infection status (P < 0.0001), as did additive (P < 0.0001) and dominance (P < 0.0022) effects. Predicted probabilities of infection for ewes with diplotypes "1 1," "1 3," and "3 3" were 0.10, 0.88, and 0.89, respectively, and confidence intervals for diplotypes "1 3" and "3 3" were distinct from "1 1." Haplotype 3 was completely dominant to haplotype 1 at 39 mo of age. The probability of infection for ewes with either diplotype "1 3" or "3 3" averaged 8.5 times that of ewes with diplotype "1 1." Diplotype "1 3" and "3 3" ewes were highly susceptible to nonmaternal transmission of OPPV, in contrast to diplotype "1 1" ewes. Therefore, the distribution of ewes with diplotypes "1 1," "1 3," and "3 3" within a flock will influence the number of infections caused by each route of transmission. Selection and mating strategies can be implemented to produce sheep that are genetically less susceptible to OPPV infection.

Rhodotorula minuta fungemia in a ewe lamb.

An 8-month-old crossbred ewe, normal upon physical examination, was humanely euthanized for tissue collection. After approximately 3 weeks in tissue culture, fungi began budding out of cells obtained from the choroid plexus. After an additional 3 weeks, budding was observed in kidney cell cultures and eventually in monocyte cultures as well. Serum from the lamb was submitted to the Veterinary Diagnostic Laboratory at Colorado State University for fungal diagnosis and was found negative for Aspergillus, Blastomyces, Coccidioidomycosis and Histoplasmosis. DNA was isolated from fungi collected from tissue culture supernatants and used in a set of pan-fungal PCR assays with DNA from Candida acting as a positive control. PCR products were sequenced and BLAST analysis performed. The unknown fungal sequence aligned with 100% identity to Rhodotorula minuta an emerging opportunistic pathogen. Samples were submitted to The Fungal Testing Laboratory at The University of Texas Health Science Center at San Antonio for additional validation. We believe this to be the first report of Rhodotorula fungemia in a sheep in the United States.

Effects of TMEM154 haplotypes 1 and 3 on susceptibility to ovine progressive pneumonia virus following natural exposure in sheep.

Small ruminant lentiviruses (SRLV) adversely affect production and well-being of sheep and goats throughout much of the world. The SRLV, including ovine progressive pneumonia virus (OPPV) in North America, cause lifetime infections, and management procedures to eradicate or reduce disease prevalence are costly. Variants of ovine transmembrane protein 154 gene (TMEM154) affect susceptibility to OPPV. The primary experimental objective was to estimate additive and dominance effects of TMEM154 haplotypes 1 and 3 on susceptibility to OPPV infection following natural exposure. A group of 187 trial lambs was born and raised by mature, infected ewes to ensure natural exposure to OPPV. Parents of trial lambs were heterozygous for haplotypes 1 and 3, producing lambs with diplotypes "1 1," "1 3," and "3 3." A group of 20 sentinel lambs was born and raised by mature, uninfected ewes that were diplotype "1 1." Sentinel lambs had diplotypes "1 1" and "1 3," being sired by the same set of rams as trial lambs. Trial and sentinel lambs were comingled during the experiment. Lambs were weaned at 60 d of age, bled 1 wk after weaning, and thereafter at intervals of 4 or 5 wk until 9 mo of age when OPPV infection status was determined by use of a competitive enzyme-linked immunosorbent assay. Only 1 sentinel lamb became infected. Infection status of trial lambs was analyzed using logistic regression procedures to account for the binary nature of infection status and random effects of sires. Effects of sex, type of birth, type of rearing, age of dam, breed type of dam, and sires were not detected (P>0.20). Infection status was affected by diplotype of lamb (P=0.005), with additive (P=0.002) and dominance (P=0.052) effects identified. Predicted probabilities of infection for lambs with diplotypes "1 1," "1 3," and "3 3" were 0.094, 0.323, and 0.346, respectively. Confidence intervals for probabilities of infection for diplotypes "1 3" and "3 3" were similar, but distinct from diplotype "1 1." These results are consistent with complete dominance of haplotype 3 relative to haplotype 1. The probability of infection at 9 mo of age for lambs with either diplotype "1 3" or "3 3" averaged 3.56 times that of lambs with diplotype "1 1." Genetic susceptibility to OPPV infection can be reduced by selection to increase the frequency of haplotype 1, resulting in a greater proportion of lambs with diplotype "1 1."

The change in differing leukocyte populations during vaccination to bovine respiratory disease and their correlations with lung scores, health records, and average daily gain.

Bovine respiratory disease (BRD) is the most economically important disease in U.S. feedlots. Infection can result in morbidity, mortality, and reduced average daily gain. Cheap and reliable genetic methods of prediction and protection from BRD would be highly advantageous to the industry. The immune response may correlate with BRD incidence. Cattle (n = 2,182) were vaccinated against common viral and bacterial pathogens of BRD. Two blood samples were collected, one during booster vaccination and one 21d later, enabling 3 phenotypes for each trait [prebooster (pre), postbooster (post), and delta (post minus pre)]. From the blood samples innate and adaptive responses [counts of white blood cells (WBC), neutrophils, lymphocytes, monocytes, eosinophils, and basophils] were measured. In addition, feedlot ADG and binary traits [health records (HR; 0 = healthy, 1 = ill) and lung scores (LS; collected at harvest; 0 = no lesions, 1 = lesions)] were also recorded. Traits ADG, HR, and LS have all been significantly correlated with infection to BRD. In this investigation we aimed to find correlations between the immune response and ADG, HR, and LS to find an easily measurable trait that would be a good predictor of BRD resistance after vaccination. The results showed an average positive delta for the innate immune response (eosinophils, basophils, neutrophils), whereas the adaptive immune response had an average negative delta (lymphocytes). Overall, we discovered that the immune responses had moderately high heritabilities (h(2); lowest: delta monocytes, 0.21 ± 0.05; greatest: pre lymphocytes: 0.5 ± 0.05), with lymphocytes having the greatest h(2) throughout the study (h(2) ≥ 0.41). All genetic correlations were calculated using bivariate REML models. Although LS did not significantly correlate with any of the immune phenotypes, both ADG (post lymphocytes, -0.24 ± 0.12) and HR (pre eosinophils, -0.67 ± 0.29; delta WBC, -0.5 ± 0.24, and delta lymphocytes, -0.67 ± 0.21) did. All the significant genetic correlations with HR were negative; resistance to BRD appears to be a function of greater delta lymphocytes and WBC. The increase in eosinophils may potentially link its role in decreasing lymphocytes. These results may enable producers to predict if revaccination, quarantine, and breeding of animals is required to reduce the incidence of BRD postvaccination. In addition, immunological phenotypes maybe used to aid genomic selection indices to select animals with greater rates of protection after BRD vaccination.

Identification of an ionotropic glutamate receptor AMPA1/GRIA1 polymorphism in crossbred beef cows differing in fertility.

A proposed functional polymorphism in the ionotropic glutamate receptor AMPA1 (GRIA1) has been reported to influence antral follicle numbers and fertility in cows. Repeat breeder cows that fail to produce a calf in multiple seasons have been reported to have reduced numbers of small (1 to 3 mm) antral follicles in their ovaries. Therefore, we tested the hypothesis that this GRIA1 polymorphism was affecting antral follicle numbers in repeat breeder cows. Repeat breeder cows (n = 64) and control cows (n = 72) that had always produced a calf were housed in a dry lot and observed twice daily for behavioral estrus. Blood samples were collected, and cows were genotyped for this GRIA1 polymorphism and for a polymorphism in the GnRH receptor (GnRHR) that was proposed to influence age at puberty. On d 3 to 8 after estrus cows were slaughtered, and reproductive organs were collected to determine antral follicle count, ovary size, and uterine horn diameter. Repeat breeder cows were older at first calving than control cows (P = 0.006). The length (P = 0.03) and height (P = 0.02) of the ovary contralateral to the corpus luteum (CL) were greater in control cows than repeat breeder cows. The endometrial diameter in the horn ipsilateral to the CL was greater in the control cows than the repeat breeder cows. Repeat breeder cows had fewer small (1 to 5 mm) antral follicles than control cows (P = 0.003); however, there was no association between GRIA1 genotype and antral follicle number. The GnRHR polymorphism was associated with age at first calving because cows that were homozygous for the C allele had a greater age at first calving than heterozygous cows or cows that were homozygous for the T allele (P = 0.01). In the granulosa cells from small (1 to 5 mm) antral follicles, mRNA abundances of 2 markers of oocyte quality, anti-Müllerian hormone and pentraxin 3, did not differ between fertility groups (P ≥ 0.12). We conclude that this GRIA1 polymorphism exists in beef cows but that it does not influence antral follicle numbers. The association between GnRHR genotype and age at first calving is likely not causal as this polymorphism is not functional. The utility of this polymorphism as a genetic marker for early conception in heifers will require further validation. Screening postpartum cows by ultrasonography to determine antral follicle numbers may aid in making culling decisions.

Development of cell lines from the sheep used to construct the CHORI-243 Ovine BAC library.

Two cell lines, designated MARC.OVSM, and MARC.OKF, were initiated from the aorta and kidney, respectively, obtained from the Texel ram used to make the CHORI-243 Ovine BAC library. These cell lines have been submitted to the NIA Aging Cell Repository at the Coriell Cell Respositories, Camden, NJ, USA, and will be made publicly available.

Interferon type I response in porcine reproductive and respiratory syndrome virus-infected MARC-145 cells.

Infection by porcine reproductive and respiratory syndrome virus (PRRSV) results in a weak induction of the innate immune response. There are many genes that collectively comprise this response and the extent to which each gene responds to PRRSV infection is unclear and warrants further investigation. To this end, we have utilized real-time PCR using SYBR Green I dye-based detection to quantify transcript abundance of the type I interferons (IFN-alpha and -beta) and IFN-beta transcriptional enhanceasome genes. In MARC-145 cells, both IFN-alpha and -beta transcript abundance were unaffected by PRRSV infection. However, stimulation of MARC-145 cells by exogenous double-stranded RNA, resulted in significant increases in transcript abundance of both IFN-alpha and -beta as well as IFN-beta enhanceasome components, indicating that a type I IFN response could be induced in these cells. The double-stranded RNA induction of type I IFN transcription was significantly inhibited by dual-exposure with PRRSV. These results suggest that PRRSV infection directly interferes with type I IFN transcriptional activation early in its pathway, at the level of IFN-beta gene transcription.

Sequence evaluation of four pooled-tissue normalized bovine cDNA libraries and construction of a gene index for cattle.

An essential component of functional genomics studies is the sequence of DNA expressed in tissues of interest. To provide a resource of bovine-specific expressed sequence data and facilitate this powerful approach in cattle research, four normalized cDNA libraries were produced and arrayed for high-throughput sequencing. The libraries were made with RNA pooled from multiple tissues to increase efficiency of normalization and maximize the number of independent genes for which sequence data were obtained. Target tissues included those with highest likelihood to have impact on production parameters of animal health, growth, reproductive efficiency, and carcass merit. Success of normalization and inter- and intralibrary redundancy were assessed by collecting 6000-23,000 sequences from each of the libraries (68,520 total sequences deposited in GenBank). Sequence comparison and assembly of these sequences was performed in combination with 56,500 other bovine EST sequences present in the GenBank dbEST database to construct a cattle Gene Index (available from The Institute for Genomic Research at http://www.tigr.org/tdb/tgi.shtml). The 124,381 bovine ESTs present in GenBank at the time of the analysis form 16,740 assemblies that are listed and annotated on the Web site. Analysis of individual library sequence data indicates that the pooled-tissue approach was highly effective in preparing libraries for efficient deep sequencing.

Estimation of DNA sequence diversity in bovine cytokine genes.

DNA sequence variation provides the fundamental material for improving livestock through selection. In cattle, single nucleotide polymorphisms and small insertions/deletions (collectively referred to here as SNPs) have been identified in cytokine genes and scored in a reference population to determine linkage map positions. The aim of the present study was twofold: first, to estimate the SNP frequency in a reference population of beef cattle, and second, to determine cytokine haplotypes in a group of sires from commercial populations. Forty-five SNP markers in DNA segments from nine cytokine gene loci were analyzed in 26 reference parents. Comparison of all 52 haploid genomes at each PCR amplicon locus revealed an average of one SNP per 143 bp of sequence, whereas comparison of any two chromosomes identified heterozygous sites, on average, every 443 bp. The combination of these 45 SNP genotypes was sufficient to uniquely identify each of the 26 animals. The average number of haplotype alleles (4.4) per PCR amplicon (688 bp) and the percentage heterozygosity among founding parents (50%) were similar to those for microsatellite markers in the same population. For 49 sires from seven common breeds of beef cattle, SNP genotypes (1,225 total) were obtained by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) at three amplicon loci. All three of the amplicon haplotypes were correctly deduced for each sire without the use of parent or progeny genotypes. The latter allows a wide range of genetic studies in commercial populations of cattle where genotypic information from relatives may not be available.

Quantitative and qualitative signals determine T-cell cycle entry and progression.

Cell growth and proliferation as well as cell cycle arrest and apoptosis all play integral roles in the cellular immune response. The signals that lead to cytokine production by antigen- or mitogen-stimulated T cells have been studied in detail. However, it is not fully understood how these signals promote cell cycle entry and progression to DNA synthesis in T lymphocytes, especially in primary cells. We used a model distinguishing between competence and progression phases to examine quantitative and qualitative differences in signal transduction that resulted in cell cycle entry and G1 phase arrest or led to DNA synthesis in human T cells. Resting peripheral blood T cells were rendered competent by stimulation with submitogenic concentrations of phytohemagglutinin (PHA) or they were stimulated to proliferate using mitogenic concentrations of PHA. The competent state (that is, the capacity to proliferate in response to exogenous IL-2) was characterized by calcium mobilization, a protein kinase C-dependent internalization of CD3, increased mitogen-activated protein kinase (MAPK) activity, transient translocation of AP-1 transcription factors to the nucleus, expression of immediate early genes, activation of G1-phase cyclin-dependent kinases, and increased CD25 (IL-2Ralpha) expression. However, all of these events were of lesser magnitude in T cells rendered competent than in T cells stimulated to proliferate. Furthermore, the mitogenic stimulus induced a different pattern of MAPK activation and sustained translocation of AP-1 to the nucleus with concomitant IL-2 production. The data indicate that quantitative and qualitative differences in early signaling events distinguish the acquisition of the competent state or the induction of cytokine production with a commitment to T-cell proliferation.

Single nucleotide polymorphism (SNP) discovery and linkage mapping of bovine cytokine genes.

Polymorphic markers at bovine gene loci facilitate the integration of cattle genetic maps with those of humans and mice. To this end, 31 single nucleotide polymorphism (SNP) markers were developed for seven bovine chemokine genes. Loci were amplified from bovine genomic DNA by the polymerase chain reaction, and candidate amplicons were sequenced to determine their identity. Amplified loci from 24 founding parents and select progeny from a beef cattle reference population were sequenced and analyzed for SNPs. SNP haplotype alleles were determined by examining segregation patterns and used to establish the locus position on the bovine linkage map. Loci for growth-related proteins (GRO3, GRO1, and GROX) were clustered with the related CXC chemokine genes, interleukin (IL) 8, and epithelial cell inflammatory protein 1, at 84 cM from the centromeric end of the bovine chromosome (BTA) 6 linkage group. Bovine loci for a cluster of IL8 receptors, a stromal cell-derived factor 1, interferon-gamma, and tumor necrosis factor-alpha were mapped at 90, 55, 59, and 34 cM, respectively, from the centromeric ends of the BTA 2, 28, 5, and 23 linkage groups. The positions of these bovine loci were compared with those of orthologous loci on the human map to refine the boundaries of conserved synteny. These seven loci provide examples of SNP development in which the efficiency was largely dependent on the availability of bovine genomic or cDNA sequence. The polymorphic nature of these SNP haplotype markers suggests that they will be useful for mapping complex traits in cattle, such as resistance to infectious disease.

Clues to immune function and oncogenesis provided by events that activate the cell cycle machinery in normal human T cells.

A common feature seen in states of decreased immune competence or immunosuppression and in diseases of the blood, such as lymphohematopoietic cancers, is the disruption of the normal pathways of cell cycle control. In lymphocytes a series of nonlinear biochemical cascades leads to cellular proliferation and also controls the production of cytokines that provide immunologic help (i.e., aid in B and T cell proliferation, maturation, and differentiation). These two distinct outcomes can be dissociated, as stimuli that incite production of cytokines need not lead to cell division, and conversely, exogenously provided cytokines may promote lymphocyte proliferation. The signals that induce production of cytokines, particularly interleukin-2, have been extensively characterized. It also is known that the fidelity of cell cycle progression is dependent on a regulatory network whose key components include cyclin-dependent kinases and cyclins. This review describes the current state of knowledge linking the antigen receptor response pathways and the activation of the cell cycle machinery in T cells.

Immunization with Babesia bigemina rhoptry-associated protein 1 induces a type 1 cytokine response.

Rhoptry-associated protein-1 (RAP-1) homologues of Babesia bigemina and Babesia bovis are promising candidates for inclusion in subunit vaccines against these hemoprotozoan parasites. Partial protection against challenge infection has been achieved with native forms of these antigens, but the mechanism of immunity has not been thoroughly defined. We previously demonstrated that a panel of antigen-specific T helper cell clones derived from B. bigemina RAP-1-immunized cattle expressed relatively high levels of interferon-gamma (IFN-gamma) protein and transcript and low levels of interleukin-4 (IL-4), indicative of a type 1 immune response. In the current study we present evidence that subcutaneous immunization with native B. bigemina RAP-1 protein in RIBI adjuvant induces a predominant type 1 immune response in vivo, characterized by relatively high levels of IFN-gamma and IL-2 and low levels of IL-4 and IL-10 mRNA in the draining prescapular lymph node. Ex vivo restimulation of draining lymph node lymphocytes with specific antigen resulted in proliferation and enhanced expression of IL-2 and IFN-gamma, whereas IL-4 and IL-10 transcript levels remained relatively low. These findings show that our previously described cytokine profiles of antigen-specific cloned T cell lines are representative of autologous in vivo responses and confirm that type 1 recall responses to B. bigemina RAP-1 can be evoked in immunized animals by native parasite antigen.

Babesia bovis rhoptry-associated protein 1 is immunodominant for T helper cells of immune cattle and contains T-cell epitopes conserved among geographically distant B. bovis strains.

The ability of rhoptry-associated protein 1 (RAP-1) of Babesia bovis and Babesia bigemina to confer partial protective immunity in cattle has stimulated interest in characterizing both B-cell and T-cell epitopes of these proteins. It was previously shown that B. bovis RAP-1 associates with the merozoite surface as well as rhoptries and expresses B-cell epitopes conserved among otherwise antigenically different B. bovis strains. An amino-terminal 307-amino-acid domain of the molecule that is highly conserved in the B. bigemina RAP-1 homolog did not contain cross-reactive B-cell epitopes. The studies reported here demonstrate that B. bovis RAP-1 is strongly immunogenic for T helper (Th) cells from B. bovis-immune cattle and that like B-cell epitopes, Th-cell epitopes are conserved in different B. bovis strains but not in B. bigemina RAP-1. Lymphocytes from cattle immune to challenge with the Mexico strain of B. bovis proliferated against recombinant B. bovis RAP-1 protein derived from the Mexico strain. T-cell lines established by stimulating lymphocytes with recombinant RAP-1 protein responded against B. bovis, but not B. bigemina, merozoites. T-cell lines established by repeated stimulation of lymphocytes with B. bovis membrane antigen proliferated strongly against RAP-1, demonstrating the immunodominant nature of this protein. RAP-1-specific CD4+ T cell clones recognized Mexico, Texas, Australia, and Israel strains of B. bovis but neither B. bigemina merozoites nor recombinant B. bigemina RAP- 1. Analysis of cytokine mRNA in RAP-1-specific Th cell clones revealed strong expression of gamma interferon but little or no expression of interleukin-2 (IL-2), IL-4, or IL-10. Gamma interferon production was confirmed by enzyme-linked imunosorbent assay. These results indicate the potential to use selected B. bovis RAP-1 peptides as immunogens to prime for strong, anamnestic, strain-cross-reactive type 1 immune responses upon exposure to B. bovis.

Interleukin-10 downregulates proliferation and expression of interleukin-2 receptor p55 chain and interferon-gamma, but not interleukin-2 or interleukin-4, by parasite-specific helper T cell clones obtained from cattle chronically infected with Babesia bovis or Fasciola hepatica.

Human recombinant interleukin-10 (IL-10) was previously shown to inhibit accessory cell (AC)-dependent proliferation of bovine parasite-specific T helper 1 (Th1), Th2, and Th0 cells in an IL-2-reversible manner (Brown, W.C., Woods, V.M., Chitko-McKown, C.G., Hash, S.M., and Rice-Ficht, A.C., 1994. Infect. Immun. 62, 4697-4708). The present study was therefore designed to determine whether the effect of IL-10 on T cell proliferation corresponded with downregulated expression of cytokines, or their receptors, important for T cell growth. The effects of IL-10 on cellular proliferation and expression of IL-2, IL-4, IL-2 receptor (IL-2R; p55), and IFN-gamma by Babesia bovis- or Fasciola hepatica-specific Th cell clones were simultaneously evaluated. As shown previously, IL-10 strongly inhibited proliferation of all types of Th cell clones, although this did not correspond with reduced expression of IL-2 or IL-4 mRNA or their products. In contrast, expression of IL-2R mRNA was consistently reduced in the IL-10-treated clones. These results indicate that IL-10 does not inhibit AC-dependent proliferation of bovine Th cells by downregulating T cell cytokines; rather, IL-10 may act by downregulating IL-2R p55 expression and subsequent signal transduction leading to decreased cellular proliferation. IFN-gamma production was also consistently downregulated in the presence of IL-10.

Influence of recombinant bovine interleukin-1 beta and interleukin-2 in pigs vaccinated and challenged with Streptococcus suis.

An experiment was conducted to determine the adjuvanticity of recombinant bovine IL-1 beta (rBoIL-1 beta) and recombinant bovine IL-2 (rBoIL-2) administered in conjunction with a single Streptococcus suis vaccination in pigs. Sixty 4-week-old pigs were allotted to eight groups: nonvaccinated controls; vaccinated controls; rBoIL-beta at 0.1, 1, and 10 micrograms kg-1; rBoIL-2 at 2.5, 25, and 250 micrograms kg-1. All pigs (except nonvaccinated controls) were vaccinated on Day 0 with a commercial Streptococcus suis vaccine (serotypes 1 and 2). At vaccination, pigs were injected intramuscularly with their respective cytokine treatments. Pigs received additional cytokine injections on 2 consecutive days. On Day 21, all pigs were challenged intravenously with 3.2 x 10(9) colony forming units of a log phase culture of S. suis (serotype 2). The highest dose of rBoIL-1 beta exceeded the maximum tolerable dose for the cytokine; however, this dose of rBoIL-1 beta protected pigs from the S. suis challenge. Pigs administered rBoIL-1 beta at 10 micrograms kg-1 had higher antibody responses to S. suis, less severe clinical signs of the disease after challenge, better growth performance during the infection, and less severe gross pathological lesions caused by the bacteria. No pigs in this treatment group died from the bacterial challenge. These data suggest that rBoIL-1 beta (10 micrograms kg-1), administered intramuscularly for 3 consecutive days at vaccination, is more effective than a single S. suis vaccination alone in protecting pigs against a S. suis challenge.