Surveillance of Bungowannah pestivirus in the upper Midwestern USA

Pestiviruses, a genetically and antigenically highly diverse group, include one of the most historically significant swine pathogens, that is, classical swine fever virus. In Australia, investigations into swine outbreaks characterized by neonatal mortality, stillbirths and mummified foetuses resulted in the discovery of a new pestivirus, Bungowannah virus. This finding raised the possibility that Bungowannah virus, or a variant thereof, was circulating in swine herds elsewhere in the World. If so, it raised the possibility of a pestivirus emerging as a new swine disease with unknown consequences for animal health and food safety. Thus, we developed three specific qRT-PCR assays to evaluate tissue samples from undiagnosed cases of abortion or respiratory disease for evidence of Bungowannah virus. Examination of 64 samples collected between the Fall of 2007 and Spring of 2010 tested negative for all three genes examined. We conclude that Bungowannah-like pestivirus is unlikely to be present in swine in the upper Midwestern USA.

Comparative faecal microbiota of dogs with and without calcium oxalate stones

AIMS

The absence of enteric oxalate-metabolizing bacterial species (OMBS) increases the likelihood of calcium oxalate (CaOx) urolithiasis in humans and dogs. The goal of this study was to compare the gut microbiota of healthy dogs and CaOx stone formed dogs (CaOx-dogs), especially with respect to OMBS.

METHODS AND RESULTS

Faecal samples from healthy and CaOx-dogs were obtained to analyse the hindgut microbiota by sequencing the V3 region of bacterial 16S rDNA. In total, 1223 operational taxonomic units (OTUs) were identified at 97% identity. Only 38% of these OTUs were shared by both groups. Significant differences in the relative abundance of 152 OTUs and 36 genera were observed between the two groups of dogs.

CONCLUSIONS

The faecal microbiota of healthy dogs is distinct from that of CaOx-dogs, indicating that the microbiota is altered in CaOx-dogs.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first study that has compared the gut microbial diversity in healthy and CaOx-dogs. Results of this study indicate the future need for functional and comparative analyses of the total array of oxalate-metabolizing genes between healthy and CaOx stone formers, rather than focusing on specific bacterial species, to understand the critical role of OMBS in CaOx urolithiasis.

Persufflation improves pancreas preservation when compared with the two-layer method

Islet transplantation is emerging as a promising treatment for patients with type 1 diabetes. It is important to maximize viable islet yield for each organ due to scarcity of suitable human donor pancreata, high cost, and the large dose of islets required for insulin independence. However, organ transport for 8 hours using the two-layer method (TLM) frequently results in low islet yields. Since efficient oxygenation of the core of larger organs (eg, pig, human) in TLM has recently come under question, we investigated oxygen persufflation as an alternative way to supply the pancreas with oxygen during preservation. Porcine pancreata were procured from donors after cardiac death and preserved by either TLM or persufflation for 24 hours and subsequently fixed. Biopsies collected from several regions of the pancreas were sectioned, stained with hematoxylin and eosin, and evaluated by a histologist. Persufflated tissues exhibited distended capillaries and significantly less autolysis/cell death relative to regions not exposed to persufflation or to tissues preserved with TLM. The histology presented here suggests that after 24 hours of preservation, persufflation dramatically improves tissue health when compared with TLM. These results indicate the potential for persufflation to improve viable islet yields and extend the duration of preservation, allowing more donor organs to be utilized.

Immune response against porcine reproductive and respiratory syndrome virus during acute and chronic infection

A significant obstacle to the prevention and control of porcine reproductive and respiratory syndrome virus (PRRSV) is the inability of current diagnostic tests to provide information concerning the stage of PRRSV infection. To explore possible prognostic combinations of cell-mediated and humoral immune responses, 3-week-old pigs (n=10) were intramuscularly (IM) inoculated with PRRSV isolate VR-2332 and followed for 193 days post-inoculation (DPI). Negative control pigs (n=10) were IM inoculated with minimum essential medium (MEM). At approximately 2-week intervals, blood samples were collected from all animals and tested for the number of interferon (IFN)-gamma-secreting peripheral blood mononuclear cells (enzyme-linked immunosorbent spot, Elispot), PRRSV viremia (quantitative reverse-transcriptase polymerase chain reaction, qRT-PCR), and serum antibodies using PRRSV protein ELISAs (N, GP5 3', GP5 5', M 5', M 3', GP5-M, and nsp2p) and a commercial PRRSV ELISA (IDEXX Laboratories Inc.). All pigs were viremic by 7 days post-inoculation, with 50% of the pigs resolving viremia by 56 DPI. A PRRSV-specific IFN-gamma response was detected at DPI 28, reached a plateau at 42 DPI, declined slightly, and remained relatively stable from 56 to 193 DPI. On the basis of ROC area under the curve (AUC) analysis, the ELISAs that most reliably differentiated PRRSV-inoculated pigs from negative control pigs were the commercial ELISA (AUC=0.97), the N ELISA (AUC=0.96), and the M 3' ELISA (AUC=0.93). Multivariate analyses were performed to evaluate the relationship between the immune response and the duration and level of viremia. With all antibody assays and Elispot included in the models, the analysis determined that the serum-virus neutralizing antibody response was the best predictor of both level and duration of viremia. It was concluded that humoral antibody responses, particularly the commercial ELISA, N ELISA, and M 3' ELISA were good predictors of prior exposure to PRRSV, but provided little information regarding the ontogeny of the protective immune response. Likewise, cell-mediated immunity based on the number of IFN-gamma-secreting lymphocytes was a poor prognosticator of PRRSV infection status.

Enhanced immunogenicity of a bivalent nicotine vaccine

The efficacy of nicotine vaccines for smoking cessation is dependent upon their ability to elicit sufficiently high serum antibody concentrations. This study compared two nicotine immunogens representing different hapten presentations, 3'-aminomethyl nicotine conjugated to recombinant Pseudomonas exoprotein A (3'-AmNic-rEPA) and 6-carboxymethlureido nicotine conjugated to keyhole limpet hemocyanin (6-CMUNic-KLH), and assessed whether their concurrent administration would produce additive serum antibody concentrations in rats. Effects of vaccination on nicotine pharmacokinetics were also studied. Vaccination of rats with these immunogens produced non cross-reacting nicotine-specific antibodies (NicAb). Serum NicAb concentrations elicited by each individual immunogen were not affected by whether the immunogens were administered alone as monovalent vaccines or together as a bivalent vaccine. The total NicAb concentration in the bivalent vaccine group was additive compared to that of the monovalent vaccines alone. Higher serum NicAb concentrations, irrespective of which immunogen elicited the antibodies, were associated with greater binding of nicotine in serum, a lower unbound nicotine concentration in serum, and lower brain nicotine concentration. These results demonstrate that it is possible to design immunogens which provide distinct nicotine epitopes for immune presentation, and which produce additive serum antibody levels. The concurrent administration of these immunogens as a bivalent vaccine may provide a general strategy for enhancing the antibody response to small molecules such as nicotine.

Transcriptional profiling of stress response in cultured porcine islets

Cell-based diabetes therapy may be achieved through xenotransplantation of adult porcine islets, but tissue quality and immunoreactivity barriers need to be overcome. Early identification and exclusion of irreversibly stressed and dying islets may improve transplant outcomes. We used oligonucleotide microarray and quantitative RT-PCR to identify molecular markers of physiological and immunological stress in porcine islets cultured under stress conditions of elevated glucose (16.7 mM), inflammatory cytokine addition (IL-1beta, TNF-alpha, and IFN-gamma), or both, for 48 h. Hyperglycemic conditions were associated with increased thioredoxin interacting protein and metabolic process mRNAs, as observed in rodent and primate species. Cytokine treatment increased expression of JAK-STAT pathway components, oxidative stress (transglutaminase 2), and beta cell dysfunction genes. Transglutaminase 2 induction is unique to porcine islets. Biomarkers involved in hyperglycemia and islet inflammation may serve as novel targets for improving and monitoring isolated porcine islet function and viability.

Mapping of genes expressed in activated porcine Peyer's patch

To determine the chromosomal locations for genes expressed in porcine Peyer's patches, polymerase chain reaction-based mapping of expressed sequence tags (ESTs) isolated from a porcine Peyer's patch-specific cDNA library was performed across a 6500-rad swine radiation hybrid panel. A total of 116 ESTs were mapped with LOD scores >6.0, and another 11 ESTs had LOD scores between 5.0 and 6.0. Of these 127 ESTs, 63% matched known genes (<e-25), 26% matched genes of unknown function, and 11% matched no sequences in the public mammalian databases. Comparative mapping information for 91% of the unknown ESTs was obtained in silico by sequence matching to human chromosomes. Placement of these ESTs on the porcine map will assist in the development of high density and comparative genetic maps for positional cloning and identification of genes responsible for immune function in the gut.

Gene discovery and expression profiling in porcine Peyer's patch

Peyer's patches of the intestinal mucosa are essential for host defense and immune regulation in the enteric system. To better understand molecular mechanisms of Peyer's patch function, we have screened for differentially expressed genes specific to Peyer's patch. cDNA libraries were created from normal Peyer's patch, immune stimulated Peyer's patch, and pooled cDNA subtracted with fibroblast RNA. From the subtracted library, 3687 expressed sequence tags (ESTs), representing 2414 unique nucleotide sequences, were isolated, identified by BLAST searches against public databases, and spotted onto a microarray for gene expression profiling. Approximately 30% of these ESTs BLAST to genes of unknown function and 20% have no known homology in the public databases (novel genes). Of the novel genes, 70% are expressed in normal immune tissues by microarray analysis, suggesting that at least 371 of the unidentified EST sequences from the subtracted library are novel porcine genes and can now be further characterized to determine their function in the porcine Peyer's patch. We surmise that the products of these genes participate in biochemical and cellular functions related to the unique immunological and gastroenterological functions of the small intestine. The BLAST and gene ontology information for each of the subtracted library EST sequences, the normal and immune stimulated libraries, and the microarray are all valuable resources that will facilitate further examination of the biological function of porcine Peyer's patch tissue.

Evolution of porcine reproductive and respiratory syndrome virus during sequential passages in pigs

Porcine reproductive and respiratory syndrome (PRRS) viruses are recognized as possessing a high degree of genetic and antigenic variability. Viral diversity has led to questions regarding the association of virus mutation and persistent infection in the host and has raised concerns vis-à-vis protective immunity, the ability of diagnostic assays to detect novel variants, and the possible emergence of virulent strains. The purpose of this study was to describe ongoing changes in PRRS virus during replication in pigs under experimental conditions. Animals were inoculated with a plaque-cloned virus derived from VR-2332, the North American PRRS virus prototype. Three independent lines of in vivo replication were maintained for 367 days by pig-to-pig passage of virus at 60-day intervals. A total of 315 plaque-cloned viruses were recovered from 21 pigs over the 367-day observation period and compared to the original plaque-cloned virus by virus neutralization assay, monoclonal antibody analysis, and sequencing of open reading frames (ORFs) 1b (replicase), 5 (major envelope protein), and 7 (nucleocapsid) of the genome. Variants were detected by day 7 postinoculation, and multiple variants were present concurrently in every pig sampled over the observation period. Sequence analysis showed ORFs 1b and 7 to be highly conserved. In contrast, sequencing of ORF 5 disclosed 48 nucleotide variants which corresponded to 22 amino acid variants. Although no epitopic changes were detected under the conditions of this experiment, PRRS virus was shown to evolve continuously in infected pigs, with different genes of the viral genome undergoing various degrees of change.

Porcine encephalomyocarditis virus persists in pig myocardium and infects human myocardial cells

Recent advances toward using pig tissues in human transplantation have made it necessary to determine the risk of transmitting zoonotic viruses from pigs to humans or vice versa. We investigated the suitability of the porcine encephalomyocarditis virus (EMCV) model for such studies by determining its ability to persist in pigs, escape detection by routine serological methods, and infect human cells. Intraperitoneal inoculation of 5-week-old pigs with EMCV-30, a strain isolated from commercial pigs, resulted in acute cellular degeneration, infiltration of lymphocytes, and apoptosis in myocardium in 13 of 15 (86.7%) pigs during the acute phase of disease (3 to 21 days postinfection), followed by less-severe lymphocytic infiltration and apoptosis in 5 of 10 (50%) pigs during the chronic phase of the disease (day 45 to 90 postinfection). In the brain, lymphocytic infiltration, neuronal degeneration, and gliosis were observed in 26 to 33% of pigs in the acute phase of disease whereas perivascular cuffing was the predominant feature during chronic disease. EMCV antigens and RNA were demonstrated in the myocardium and brain during the chronic phase of disease. Analysis of 100 commercial pigs that were negative for EMCV antibodies identified two pig hearts positive for EMCV RNA. Porcine EMCV productively infected primary human cardiomyocytes as demonstrated by immunostaining using a monoclonal antibody specific for EMCV RNA polymerase, which is expressed only in productively infected cells, and by a one-step growth curve that showed production of 100 to 1,000 PFU of virus per cell within 6 h. The findings that porcine EMCV can persist in pig myocardium and can infect human myocardial cells make it an important infectious agent to screen for in pig-to-human cardiac transplants and a good model for xenozoonosis.

Complete genome comparison of porcine reproductive and respiratory syndrome virus parental and attenuated strains

Two full-length porcine reproductive and respiratory syndrome virus (PRRSV) genomes, strain VR-2332 and its cell culture passaged descendent RespPRRS vaccine strain, were compared and analyzed in order to identify possible sites of attenuation. Of the 41 nucleotide changes, 12 resulted in conservative changes and 18 produced non-conservative changes. The results suggest that key amino acids in ORF1 may contribute to the phenotype of RespPRRS, which includes increased growth rate on MA-104 cells and decreased virulence in swine. The results provide a genetic basis for future manipulation of a PRRSV reverse genetics system.

Bacterially induced activation of interleukin-18 in porcine intestinal mucosa

Interleukin (IL)-18 is a cytokine with structural and functional properties similar to IL-1beta and IL-12, respectively. It is activated by caspase-1 cleavage, like IL-1beta, and induces interferon (IFN)-gamma, like IL-12. In order to study the role of IL-18 in the immune response to infectious diseases of mucosal surfaces we cloned and expressed porcine IL-18 and developed antibodies to the protein. Porcine IL-18 retains the caspase-1 cleavage site present in other mammalian IL-18 proteins, but has two potential N-linked glycosylation sites not found in those proteins. Porcine interleukin-18 mRNA and protein are expressed in immune tissues including lymph nodes and gut associated lymphoid tissues. Specific cell types containing IL-18 include lung and splenic macrophages, nonadherent spleen cells and intestinal epithelial cells. Although IL-18 transcription is moderately induced by lipopolysaccharide, the magnitude and total expression level are small compared to those of interleukin-1beta. In vivo and ex vivo infection of intestinal mucosa with Salmonella choleraesuis resulted in a decrease in size of IL-18, consistent with cleavage of the preprotein by caspase-1. Thus, IL-18 is present in mucosal tissues where it could play a role in the immune response to invading pathogens.

Adenovirus-mediated expression of interleukin-1 receptor antagonist in swine cells in vitro and in vivo

Adenovirus-mediated gene delivery of anticytokines is a powerful tool for modulating the cytokine environment under conditions of respiratory disease. In order to determine the feasibility of cytokine modulation in the context of respiratory disease in swine, nonreplicating E1- and E3-deficient adenovirus constructs expressing a model protein, beta-galactosidase, and an anticytokine, the IL-1 receptor antagonist (IL-1Ra), were evaluated for in vitro expression in porcine PK15 cells, and in vivo following endotracheal instillation into the lungs. beta-Galactosidase and IL-1Ra were readily expressed in vitro in swine cells. Endotracheal administration of lacZ-containing adenovirus demonstrated that endothelial and epithelial cells in the alveolar spaces and bronchi of the middle and lower lobes were the principal sites of infection and expression, whereas beta-galactosidase staining was not observed in the upper lobe. Endotracheal administration of IL-1Ra recombinant adenovirus resulted in sustained expression of IL-1Ra into the alveolar spaces, where it was recovered in a concentration of 660 pg/ml in 500 ml of lavage fluid, equivalent to 330 ng IL-1Ra, in the lungs 7 days after treatment. Moreover, in vivo instillation of nonreplicating adenovirus did not induce an inflammatory response in the 1-week time frame of the study period. Lung weight as a percent of body weight, serum zinc, serum amyloid A, leukocyte differentials, neutrophil activity, and TNF levels all were the same between untreated pigs and pigs treated with either recombinant adenovirus. The results indicate that the delivery of IL-1Ra to swine lungs via nonreplicating, recombinant adenovirus may be an effective method for in vivo modulation of IL-1 activity and investigation of cytokine involvement in respiratory disease pathogenesis.

Expression of nociceptin/OFQ receptor and prepro-nociceptin/OFQ in lymphoid tissues

This study was undertaken to examine the presence of functional nociceptin/orphanin FQ (N/OFQ) receptors in the immune system. Receptor mRNA signals were detected by RT-PCR in porcine thymus, lymph nodes, spleen and freshly-isolated splenocytes; the distribution of prepro-nociceptin/-orphanin FQ (PP-N/-OFQ) mRNA was similar, with the exception of lymph nodes. However, specific [(3)H]nociceptin binding sites were not detected in rat or porcine lymphoid tissues, and 0.1-100 nM nociceptin had no effect on forskolin-stimulated cyclic AMP concentrations in porcine splenocytes. Thus, it appears that nociceptin/orphanin FQ receptor mRNA, but not a functional receptor protein is expressed in the immune system.

Heteroclite subgenomic RNAs are produced in porcine reproductive and respiratory syndrome virus infection

Porcine reproductive and respiratory syndrome virus (PRRSV) was shown to produce atypical subgenomic RNAs that contain open reading frame la nucleotides and are present under a wide variety of culture conditions, including high and low multiplicities of infection, in simian and porcine host cells, and during infection with cell-adapted and wild-type PRIRSV strains. Sequence analysis demonstrated that they are heterogeneous in 5-3' junction sequence and size and may code for different predicted fusion proteins. This is the first report of these novel RNA5 in arteriviruses and we have termed them heteroclite (meaning 'deviating from common forms or rules") subgenomic RNAs. The unique properties of these subgenomic RNAs include (a) apparent association with normal virus infection and stability during serial passage, (b) packaging of heteroclite RNAs into virus-like particles, (c) short, heterogeneous sequences which may mediate the generation of these RNAs, (d) a primary structure which consists of the two genomic termini with one large internal deletion, and (eJ little apparent interference with parental virus replication. These subgenomic RNA5 may be critical to, or a necessary side product of, viral replication. The expression of these novel RNA species support the template-switching model of similarity-assisted RNA recombination. In summary, PRRSV readily undergoes nonhomologous RNA recombination to generate heteroclite sub-genomic RNA5.

Interleukin-10 gene therapy-mediated amelioration of bacterial pneumonia

Respiratory infection by Actinobacillus pleuropneumoniae causes a highly pathogenic necrotizing pleuropneumonia with severe edema, hemorrhage and fever. Acute infection is characterized by expression of inflammatory cytokines, including interleukin-1 (IL-1), IL-6 and IL-8. To determine if high level production of inflammatory cytokines contributed to disease pathogenesis, we investigated if inhibiting macrophage activation with adenovirus type 5-expressed IL-10 (Ad-5/IL-10) reduced the severity of acute disease. Porcine tracheal epithelial cells infected with Ad-5/IL-10 produced bioactive human IL-10. When pigs were intratracheally infected with A. pleuropneumoniae, pigs pretreated with Ad-5/IL-10 showed a significant reduction in the amount of lung damage when compared to adenovirus type 5-expressing beta-galactosidase (Ad-5/beta-Gal)-treated and untreated pigs. In addition, serum zinc levels were unchanged, the lung weight/body weight ratio (an indicator of vascular leakage) was significantly reduced, and lung pathology scores were reduced. Myeloperoxidase activity in lung lavage fluid samples, an indicator of neutrophil invasion, was decreased to levels similar to that seen in pigs not infected with A. pleuropneumoniae. Reduction in inflammatory cytokine levels in lung lavage fluid samples correlated with the clinical observations in that pigs pretreated with Ad-5/IL-10 showed a corresponding reduction of IL-1 and tumor necrosis factor (TNF) compared with untreated and Ad-5/beta-Gal-treated pigs. IL-6 levels were unaffected by pretreatment with Ad-5/IL-10, consistent with observations that IL-6 was not derived from alveolar macrophages. Since inflammatory cytokines are expressed at high levels in acute bacterial pleuropneumonia, these results indicate that macrophage activation, involving overproduction of IL-1 and TNF, is a prime factor in infection-related cases of massive lung injury.

Pathophysiologic correlates of acute porcine pleuropneumonia

OBJECTIVE

To develop and evaluate an in vivo model to study early events in the pathogenesis of acute porcine pleuropneumonia.

ANIMALS

Thirty-six 6- to 8-week-old pigs.

PROCEDURE

Pigs were inoculated intranasally or endotracheally with Actinobacillus pleuropneumoniae; inoculation routes were compared by evaluation of clinical signs, gross and microscopic lung lesions, hematologic changes, serum zinc, iron, and haptoglobin concentrations, and inflammatory cytokines.

RESULTS

The 2 inoculation routes resulted in similar findings, although intranasal inoculation caused unilateral gross lung lesions, whereas endotracheal inoculation caused bilateral gross lesions. Clinical signs of disease were observed < 2 hours after endotracheal inoculation and 6 to 8 hours after intranasal inoculation. Total WBC counts did not differ significantly after inoculation by either inoculation route, although band neutrophils increased significantly. The earliest findings associated with A pleuropneumoniae inoculation, irrespective of route, were decreased serum zinc and iron concentrations. Serum haptoglobin concentrations were significantly increased after inoculation. Inoculation induced rapid influx of macrophages into the lung and local induction of proinflammatory cytokines. Northern blot analysis of total RNA from lung tissue indicated that inoculated pigs had increased concentrations of interleukin (IL)-1beta, IL-1alpha, and IL-8; tumor necrosis factor messenger RNA concentration was not increased.

CONCLUSIONS

Endotracheal inoculation with A pleuropneumoniae rapidly and consistently induced diffuse bilateral pneumonia; thus, this method may be useful for the study of acute pathophysiologic changes associated with bacterial pneumonia and may provide an experimental model for testing modalities for prevention and treatment of this and other respiratory tract diseases of pigs.

Mechanisms of vaccine adjuvanticity at mucosal surfaces

The vast majority of pathogens invade via mucosal surfaces, including those of the intestine. Vaccination directly on these surfaces may induce local protective immunity and prevent infection and disease. Although vaccine delivery to the gut mucosa is fraught with obstacles, immunization can be enhanced using adjuvants with properties specific to intestinal immunity. In this review, we present three general mechanisms of vaccine adjuvant function as originally described by Freund, and we discuss these principles with respect to intestinal adjuvants in general and to the prototypical mucosal adjuvant, cholera toxin. The key property of intestinal adjuvants is to induce an immunogenic context for the presentation of the vaccine antigen. The success of oral vaccine adjuvants is determined by their ability to induce a controlled inflammatory response in the gut-associated lymphoid tissues, characterized by the expression of various costimulatory molecules and cytokines. An understanding of the specific molecular mechanisms of adjuvanticity in the gut will allow the rational development of safe and effective oral vaccines.

In vitro and in vivo bioactivity of single-chain interleukin-12

Interleukin-12 is a heterodimeric cytokine with potent immunoregulatory properties, making it a potential vaccine adjuvant and an immune response modulator. The study of its function is confounded by its heterodimeric structure. In order to facilitate the study of interleukin-12 in both in vitro and in vivo models, we constructed a single-chain porcine interleukin-12 gene and expressed the recombinant protein in Pichia pastoris. Single-chain porcine interleukin-12 was bioactive in vitro on both human and porcine cells as measured by its ability to induce proliferation of lymphoblasts and interferon-gamma secretion by lymph node cells. In contrast, the p40 subunit of porcine interleukin-12 alone did not induce proliferation or inhibit the activity of the single-chain porcine interkeukin-12. The in vivo bioactivity of single-chain porcine interleukin-12 was demonstrated in an oral immunization model where it increased antigen-specific IgA and IgG in jejunal mucus. These results indicate that binding of interleukin-12 to its receptor and transduction of intracellular signals requires both p40 and p35 subunits. The bioactivity of interleukin-12 expressed as a single polypeptide will facilitate its in vivo delivery and study of its structure and function.

Differential regulation of macrophage interleukin-1 (IL-1), IL-12, and CD80-CD86 by two bacterial toxins

The ability of innate immune cells to differentially respond to various bacterial components provides a mechanism by which the acquired immune response may be tailored to specific pathogens. The response of innate immune cells to bacterial components provides regulatory signals to cognate immune cells. These signals include secreted cytokines and costimulatory molecules, and to a large extent they determine the quantitative and qualitative nature of the immune response. In order to determine if innate immune cells can differentially respond to bacterial components, we compared the responses of macrophages to two bacterially derived molecules, cholera toxin (CT) and lipopolysaccharide (LPS). We found that CT and LPS differentially regulated the expression of interleukin-12 (IL-12) and CD80-CD86 but not that of IL-1beta. LPS and CT each induced IL-1beta expression in macrophages, while only LPS induced IL-12 and only CT induced CD80-CD86. These differences were markedly potentiated in gamma interferon (IFN-gamma)-treated macrophages, in which LPS potently induced IL-12 and CD80-CD86 expression. In contrast, IFN-gamma treatment had no effect on the expression of IL-1beta. These results define a molecular basis for the differential pathogenicities of bacterial toxins and are relevant to the design of vaccine adjuvants able to selectively induce desired types of immunity.

Porcine reproductive and respiratory syndrome virus infection in neonatal pigs characterised by marked neurovirulence

Neonatal pigs from three herds of pigs were somnolent and inappetent and had microscopic lesions characterised by severe meningoencephalitis, necrotic interstitial pneumonia and gastric muscular inflammation. Porcine reproductive and respiratory syndrome virus (PRRSV) infection was diagnosed and confirmed by virus isolation, fluorescent antibody examination of frozen lung sections, serology, immunohistochemistry and in situ hybridisation. Each herd had a history of PRRSV infection and was using or had used a modified-live vaccine. The isolates from the affected pigs were genetically distinct from the modified-live vaccine strain of the virus when compared by restriction enzyme analysis and nucleotide sequencing of PRRSV open reading frames 5 and 6. The virus was identified in macrophages or microglia of brain lesions by immunohistochemical staining of brain sections with an anti-PRRSV monoclonal antibody and an anti-macrophage antibody. The replication of the virus in the brain was verified by in situ hybridisation. The meningoencephalitis induced by the virus in pigs from each of the herds was unusually severe and the brain lesions were atypical when compared with other descriptions of encephalitis induced by the virus, which should therefore be considered as a possible diagnosis for neonatal pigs with severe meningoencephalitis. In addition, field isolates of the virus which are capable of causing disease can emerge and coexist with modified-live vaccine virus in some pig herds.

Mucosal immunogenicity and adjuvanticity of cholera toxin in swine

The oral immunogenic and adjuvant properties of cholera toxin (CT) and its nontoxic B subunit (CT-B) were assessed in swine. Both whole CT and CT-B are oral immunogens in swine and CT is relatively more potent. Oral administration of 100 microg of CT resulted in a greater immune response than 1 mg of CT-B as measured by anti-CT-B IgA, IgG and IgM in local (jejunum) and distant (oral cavity) mucosal sites, and in systemic sites including blood and spleen. Lower doses of CT were potent adjuvants for the response to CT-B, but did not induce detectable immunity alone. The predominant response to oral CT-B administered with CT was intestinally produced and secreted IgA, with about 2500 per 10(6) jejunal lamina propria cells producing anti-CT-B IgA in immunized animals. While CT is a potent adjuvant for CT-B, its ability to act as adjuvant for heterologous proteins is more restricted. 50 microg of CT in combination with 1 mg of CT-B did not induce antibodies to 25 mg of coadministered KLH. However, chemical linking of ovalbumin to CT-B and coadministration with CT resulted in a detectable antibody response to ovalbumin. These results suggest that CT is immunogenic and is a potent adjuvant for CT-B in swine and that the induction of mucosal immunity to heterologous antigens may require specific targeting to the gut-associated lymphoid tissues.

Cloning, expression and functional role of a nociceptin/orphanin FQ receptor in the porcine gastrointestinal tract

The heptadecapeptide nociceptin/orphanin FQ is the cognate ligand for the opioid receptor-like orphanin FQ (OFQ) receptor, a member of the G protein-coupled receptor superfamily. The gastrointestinal tract is a major site of opioid action, and preliminary evidence suggests that an OFQ receptor may be expressed in rat small intestine. We addressed the hypothesis that this receptor is expressed in the gastrointestinal tract of the pig, a model for the human digestive system. A 1205-bp cDNA was isolated from porcine forebrain which contained the 370 amino acid open reading frame encoding the OFQ receptor. The receptor mRNA is likely to arise from a single gene, as determined by Southern blotting of porcine genomic DNA restriction digests using a porcine OFQ receptor cDNA probe. A semi-nested reverse transcriptase-polymerase chain reaction survey of receptor mRNA indicates that it is expressed in the porcine cerebral cortex and kidney, and along the length of the gastrointestinal tract. OFQ decreased initial contractile responses of porcine ileal smooth muscle strips to trains of electrical field stimulation with an IC50 value of 1.3 nM; its effects were resistant to the opioid antagonist, naloxone. The peptide, at concentrations > or =3 nM, also attenuated Isc elevations evoked by electrical transmural stimulation of mucosa-submucosa sheets from porcine ileum. The actions of OFQ appeared to differ from those previously reported for opioid receptor agonists in these tissue preparations. These results indicate that an OFQ receptor is expressed in the porcine intestine which modulates the neural control of intestinal smooth muscle contractility and mucosal transport.

Role of macrophage cytokines in mucosal adjuvanticity

Delivery of protein antigens to the GALT can result in immunity or oral tolerance depending on the circumstances of the encounter. One mechanism by which mucosal adjuvants can affect these circumstances is by the induction of macrophage cytokines, including IL-1 and IL-12. These cytokines can directly affect the immune response by their effects on antigen-specific T cells and by the induction of IFN-gamma by T cells or NK cells. This IFN-gamma also activates macrophages to up-regulate MHC or costimulatory molecules and by further inducing IL-1 and IL-12. In effect, mucosal adjuvants function both directly and indirectly as activators of antigen presenting cells, resulting in stimulation of the immune response to coincidental antigens. Our studies in swine have shown CT is a potent mucosal adjuvant for CT-B. CT also increased IL-1 and IL-12 mRNA in cultured macrophages, especially after activation with IFN-gamma. The effect of CT on the secretion of bioactive IL-12 protein is currently being investigated. While the mucosal adjuvanticity of CT involves a variety of mechanisms, these findings suggest a role for the induction of the macrophage cytokines IL-1 and IL-12.

Porcine reproductive and respiratory syndrome virus comparison: divergent evolution on two continents

Porcine reproductive and respiratory syndrome virus (PRRSV) is a recently described arterivirus responsible for disease in swine worldwide. Comparative sequence analysis of 3'-terminal structural genes of the single-stranded RNA viral genome revealed the presence of two genotypic classes of PRRSV, represented by the prototype North American and European strains, VR-2332 and Lelystad virus (LV), respectively. To better understand the evolution and pathogenicity of PRRSV, we obtained the 12,066-base 5'-terminal nucleotide sequence of VR-2332, encoding the viral replication activities, and compared it to those of LV and other arteriviruses. VR-2332 and LV differ markedly in the 5' leader and sections of the open reading frame (ORF) 1a region. The ORF 1b sequence was nearly colinear but varied in similarity of proteins encoded in identified regions. Furthermore, molecular and biochemical analysis of subgenomic mRNA (sgmRNA) processing revealed extensive variation in the number of sgmRNAs which may be generated during infection and in the lengths of noncoding sequence between leader-body junctions and the translation-initiating codon AUG. In addition, VR-2332 and LV select different leader-body junction sites from a pool of similar candidate sites to produce sgmRNA 7, encoding the viral nucleocapsid protein. The presence of substantial variations across the entire genome and in sgmRNA processing indicates that PRRSV has evolved independently on separate continents. The near-simultaneous global emergence of a new swine disease caused by divergently evolved viruses suggests that changes in swine husbandry and management may have contributed to the emergence of PRRS.

Detection of porcine reproductive and respiratory syndrome virus by reverse transcription-polymerase chain reaction using different regions of the viral genome

Serologic studies have revealed strain variability between American and European isolates and among American isolates of porcine reproductive and respiratory syndrome virus (PRRSV). The objective of this study was to develop an assay for the routine diagnosis of PRRSV in field specimens using reverse transcription-polymerase chain reaction (RT-PCR) amplification of conserved genomic regions. Twenty-four field isolates of PRRSV from different regions of the USA were analyzed in the study. Six primer pairs from open reading frames (ORFs) 4, 6, and 7 of the American strain (ATCC VR-2332) and from ORF 1b of the Lelystad strain were used for the amplification of the viral genome by PCR. Amplification products of the expected sizes were obtained from all isolates by PCR amplification of ORF 7, the gene encoding the nucleocapsid protein. Oligonucleotide primers designed to amplify ORFs 4 and 6 detected 92% and 96% of the isolates, respectively, whereas primers for the amplification of ORF 1b detected 88% of all isolates. The specificity of the amplified products of ORF 7 from 7 field isolates and 2 reference strains was confirmed by chemiluminescent hybridization using an internal digoxigenin-labeled DNA probe. Sequence analysis of this region indicated variation in the nucleotide sequence of 2 isolates that did not hybridize with the internal probe. These results indicate that ORF 7 may serve as a potential target for the detection of PRRSV strains by RT-PCR and that genomic variability should be considered when nucleic acid hybridization is used to confirm the specificity of PCR amplification for diagnostic purposes.

Genetic variation in the PRRS virus

Porcine reproductive and respiratory syndrome (PRRS) is characterized by late-term abortions and stillbirths in sows and respiratory difficulties in nursery pigs. The disease appeared in Europe and North America at approximately the same time between 1985 and 1990. The PRRS virus was isolated shortly thereafter and demonstrated unexpectedly profound differences between European (Lelystad) and North American (VR2332) isolates as measured by serological crossreactivity and nucleotide sequence similarity. In order to determine the amount of genetic variation in the PRRS virus and to understand the molecular mechanisms of viral evolution, nucleotide sequences of PRRS virus strains were determined. Comparisons among ten U.S. strains showed that variation in primary nucleotide sequence between isolates ranged from 2.5% to 7.9% for ORFs 2-7. In contrast, Lelystad virus was, on average, 35% different from US clones. These results provided direct molecular evidence that US and European PRRSV isolates represented genetically distinct groups of the same viral family. A further analysis of more than 150 isolates in the United States and Canada demonstrated that the PRRS virus in North America represents a single large and diverse genetic group that is distinct from European forms of the virus.

Subgenomic RNA7 is transcribed with different leader-body junction sites in PRRSV (strain VR2332) infection of CL2621 cells

Porcine reproductive and respiratory syndrome virus (PRRSV), like all members of the order Nidoviridae, is expressed in the infected cell as a nested set of subgenomic (sg) RNAs with a common 5'-leader sequence. We have determined that the 5'-leader sequence for the US prototype strain (VR2332, Collins, et al., 1992) is distinct from the European prototype strain [Lelystad (LV); Wensvoort, et al., 1991, Meulenberg et al., 1993a], yet these two strains use almost the same sequence for downstream sites of 5'-leader-body junction formation. Analysis of VR2332 genomic sequence identified several potential 5'-leader-body junction sequences upstream of open reading frame (ORF) 7, coding for the nucleocapsid protein, that could be used for generation of VR2332 sgRNA7 transcripts. Sequence determinations of RT-PCR-generated cDNA clones of sgRNA7 identified two species of RNA7 transcripts in infected cells, one utilizing a leader-body junction sequence (AUAACC) 123 nucleotides upstream of the AUG start site and one utilizing a sequence (UAAACC) 9 nucleotides upstream of the AUG start site for ORF7 translation.

The porcine mu opioid receptor: molecular cloning and mRNA distribution in lymphoid tissues

The porcine mu opioid receptor (pMOR), was cloned from cerebral cortex RNA using PCR methodologies. Porcine MOR is 96% identical with human MOR in amino acid sequence. An RT-PCR survey for pMOR mRNA indicated that pMOR is widely distributed in the gut, and is present in thymus and Peyer's patches but absent in other immune tissues and in isolated immune cells. Based on these findings, it appears that opioids do not exert an immunosuppressive effect through direct interaction with the mu-opioid receptor on immune cells. In certain tissues, however, opioids may modulate immune function indirectly through neuronal MOR.

Construction of internal cDNA competitors for measuring IL-10 and IL-12 cytokine gene expression in swine

A competitive PCR assay (cPCR) was used to quantify swine cytokine responses to parasite infection. Internal standards (deleted cDNA competitor molecules [DcDNA mimics]) were produced and tested for swine interleukin-12 (IL-12), interleukin-10 (IL-10) and hypoxanthine phosphoribosyltransferase (HPRT) from PCR generated cDNA cloned in plasmid vectors. Deletion clones for the cDNA competitor molecules (DcDNA mimics) were generated for IL-10, IL-12 and HPRT by PCR in a single step and verified by (1) amplification of the expected smaller PCR product with the original primers, (2) appropriate fragment size released by restriction digestion of the deleted clone, and (3) correct sequence of the new DcDNA insert. DcDNA mimics were used to quantitate cytokine gene mRNA production during experimental and natural infections of swine with the gastrointestinal nematode parasite Trichuris suis. Mesenteric lymph node cells were collected from control and infected pigs at the time of maximal pathogenicity (35 days after infection) and snap frozen. After RNA extraction, samples were reverse transcribed (RT) to cDNA. cPCR was performed using the housekeeping gene HPRT DcDNA mimic and HPRT specific primers to insure RNA integrity and concentration. Cytokine cDNA content in these samples was then quantitated using cytokine mimics and gene specific primers. IL-10 gene expression in MLN draining the colon of pigs experimentally infected with T. suis increased 10-20 fold at day 35 compared to control pigs. IL-12 gene expression was not detectable in MLN of these pigs, but was detectable in MLN of pigs exposed naturally to T. suis on a contaminated dirt lot that also exhibited signs of secondary bacterial invasion. Swine IL-10 and IL-12 gene expression can be quantitated in local mesenteric tissues. This cPCR assay will enable scientists to quantitate cytokine gene expression in swine and determine the nature of immune responses to important infectious diseases.

Regulation of hypoxanthine phosphoribosyltransferase, glyceraldehyde-3-phosphate dehydrogenase and beta-actin mRNA expression in porcine immune cells and tissues

Various "housekeeping" genes are often used as endogenous controls in gene expression experiments. We have cloned from swine, three genes commonly used as endogenous controls in other species and have characterized their relative levels of expression in various porcine tissues and their response to various cell activators. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and beta-actin were readily detected by northern hybridization in various tissues and in alveolar macrophages. The expression of hypoxanthine phosphoribosyltransferase (HPRT) was detected only by northern hybridization of poly-A+ enriched RNA and by reverse transcriptase-polymerase chain reaction (RT-PCR), making it more suitable for highly sensitive detection methods. Expression of GAPDH varied less among tissues than did beta-actin, making it more useful control for comparisons of gene expression between tissues with northern hybridizations. Various treatments of cultured alveolar macrophages differentially affected levels of beta-actin and GAPDH, while HPRT expression was unchanged in alveolar macrophages or spleen cells similarly treated. Therefore, while HPRT can be used as the endogenous control with sensitive detection methods such as RT-PCR, less sensitive detection methods require a more abundant gene such as GAPDH.

Delta-opioid receptor mRNA expression and immunohistochemical localization in porcine ileum

Opiates have potent antidiarrheal actions that are mediated in part by delta-opioid receptors (DOR). We examined DOR localization within subregions of porcine ileum, a tissue analogous to human small bowel. A partial cDNA sequence for porcine DOR was obtained after reverse transcription-polymerase chain reaction cloning of forebrain RNA; it encoded the end of transmembrane domain 1 through the beginning of transmembrane domain 7 and exhibited 93% nucleotide identity with human DOR. Positive signals for DOR mRNA were found in all subregions of the porcine ileal wall. With an antiserum recognizing an N-terminal epitope in murine DOR, DOR-like immunoreactivity was localized in neurons within myenteric and submucous ganglia, longitudinal and circular smooth muscle, and villous lamina propria. The DOR agonist [D-Ser2, Leu5, Thr6]enkephalin (DSLET) attenuated circular smooth muscle contractions in porcine ileum that were evoked by electrical stimulation of myenteric cholinergic neurons. These results are consistent with previous reports of the DOR-mediated neuromodulation that underlies the antipropulsive and antisecretory effects of opioids in the intestinal tract.

Inducible nitric oxide synthase expression in porcine immune cells

Porcine immune cells were examined for the ability to produce inducible nitric oxide synthase following in vitro or in vivo stimulation. Enzyme activity and product formation were not detected following stimulation of porcine peripheral blood mononuclear cells (PBMC), splenocytes, or alveolar macrophages with a combination of ConA and lipopolysaccharide (LPS) or recombinant porcine interferon gamma and LPS. In vitro engulfment of Haemophilus parasuis by macrophages also failed to induce inducible nitric oxide synthase (iNOS) activity or nitrite formation. Swine Herpes Virus infection led to a small but significant increase in level of nitrite detected in lung lavage fluid, whereas the infection of pigs with Porcine Respiratory and Reproductive Syndrome Virus did not alter the lavage fluid nitrite levels. iNOS mRNA was detected in both stimulated and unstimulated porcine immune cells and in macrophages from both control and infected animals suggesting that it is constitutively expressed with little or no upregulation following cellular stimulation. The results presented in this paper indicate that the reactive nitrogen intermediate pathway is not an vital innate immune response in the pig.

Monoclonal antibodies putatively identifying porcine B cells

Comparison was made of the binding of 38 test and three standard monoclonal antibodies (mAbs) to B cells from various pig lymphoid tissues by flow cytometry (FCM) and immunohistochemistry. Some mAbs were also tested on B cells from foetal pig tissues. Twenty of the new mAbs bound, though to variable degrees, to porcine B cells but only three were given cluster assignations: C35 (#147) and BB6-11C9 (#167) were assigned to wCD21 and 2F6/8 (#057) was assigned to SWC7.

Workshop studies with monoclonal antibodies identifying a novel porcine differentiation antigen, SWC9

Two monoclonal antibodies (mAb) within cluster M4 of the myeloid section of the Second International Swine CD Workshop, C4 (No. 144) and PM18-7 (No. 192), showed reactivity with thymocytes and among cells of myelomonocytic origin with mature macrophages but not with monocytes and granulocytes. Both mAb recognize a protein showing two bands of 205 kDa and 130 kDa under both reducing and non-reducing conditions. Although epitope mapping with these mAb could not be performed, this cluster received the SWC9 designation.

Comparison of four RNA extraction methods for the detection of porcine reproductive and respiratory syndrome virus by RT-PCR

We compared four commercial RNA isolation methods for the extraction of RNA from porcine reproductive and respiratory syndrome virus (PRRSV). The sensitivity of the methods was determined by extraction of RNA from serial 10-fold dilutions of PRRSV diluted in PRRSV-negative porcine serum or in Eagle's minimal essential medium (EMEM) followed by amplification of extracted nucleic acids by RT-PCR. The PCR products were detected in ethidium bromide-stained agarose gels. The QIAamp viral kit, which is based on binding of RNA to silica particles, was the most sensitive, allowing the detection of an equivalent of 10 TCID50 of virus in 100 microliters of serum or EMEM. The QIAamp-tissue and the TRIzol LS kits detected 100 TCID50 per 100 microliters in both diluents whereas Ultraspec-3 detected 100 TCID50 of virus in EMEM and 1000 TCID50 in serum. These results indicate that QIAamp viral kit has a higher sensitivity for RT-PCR analysis of PRRSV.

Association of tumour necrosis factor and acute phase reactant changes with post arrival disease in swine

Severe weight loss in the absence of respiratory, enteric or systemic clinical disease or gross pathologic lesions is often observed when immunologically naive boars are placed in conventional health swine facilities. Affected animals develop this weight loss in spite of receiving pre-entry vaccinations against common swine pathogens, such as Haemophilus parasuis or Mycoplasma hyopneumoniae. In many cases, the weight loss is non-responsive to long term antibiotic therapy. In order to determine the relationships between the severity of post arrival weight loss and disease and its potential immunological or physiological indicators, tumour necrosis factor (TNF) and acute phase reactant levels were correlated with the clinical status in immunologically naive boars following their transfer to a conventional facility. Boars had higher TNF (P < 0.0001) and plasma protein (P = 0.0054) levels and decreased zinc (P = 0.0004) levels during periods of clinical sickness. Likewise, peak and average plasma TNF, serum haptoglobin, and serum zinc were correlated indicating a prolonged stress or pathogenic insult (r = 0.89, P < 0.0001 for TNF; r = 0.67, P = 0.01 for haptoglobin; r = 0.73, P = 0.005 for zinc). An acute phase response, a systemic TNF increase and the development of a lymphopenia were observed in post arrival disease in swine. This is the first time cytokines and acute phase reactants have been investigated in a field study involving immunologically naive or high health swine.

Linkage assignment of eleven genes to the porcine genome

We report comparative linkage mapping of eleven genes in the swine genome by RFLP analysis. These genes include: Acid phosphatase type 5 (ACP5), Cholecystokinin Type B Receptor (CCKBR), Antibiotic Peptide (FALL39), Insulin-like Growth Factor 1 Receptor (IGF1R), Integrin Alpha M (ITGAM), Integrin Beta 2 (ITGbeta2), Opioid Receptor Mu-1 (OPRM1), Pro-hormone Converter (PC1/3), Retinol Binding Protein 3 (RBP3), Ribosomal DNA (RNR1), and Zona Pellucida Glycoprotein 1 (ZP1). The CCKBR and ITGbeta2 loci define the ends of the linkage groups on Chromosomes (Chro) (SSC) 9p and 13qter, respectively.

Molecular cloning and mRNA expression of porcine interleukin-12

Interleukin (IL)-12 is a heterodimeric cytokine consisting of 35 and 40 kDa subunits, produced primarily by phagocytic cells in response to bacteria or bacterial products. IL-12 is important in the regulation of both innate and antigen-specific immunity through its stimulatory effects on NK cells and cytotoxic lymphocytes. Reverse transcriptase-polymerase chain reaction with primers derived from human sequence was used to clone the p35 and p40 subunits of porcine IL-12. Predicted amino acid sequences for both subunits are approximately 85% homologous to their human cognates but contain a 3aa addition and a 4aa deletion in p35 and p40 subunits, respectively. The high degree of similarity indicates the proteins may be cross reactive, an important consideration in pig-human xenotransplantation. Both subunits of pIL-12 are constitutively expressed in a variety of porcine tissues. Highest levels of the p40 subunit were found in lymphoid tissues including inguinal and mesenteric lymph nodes, Peyer's patches, spleen and thymus. The p35 subunit was also detected in these tissues. Levels of mRNA encoding the p40 subunit, but not the p35 subunit, were rapidly increased in alveolar macrophages stimulated with lipopolysaccharide or killed Staphylococcus aureus. Thus, the heterodimeric subunits appear to be differentially regulated at the transcriptional level. Since p40 also self-associates to form inactive homodimers, differential expression may be a mechanism for regulating IL-12 activity.

Coincidental changes in behavior and plasma cortisol in unrestrained pigs after intracerebroventricular injection of tumor necrosis factor-alpha

The coincidental behavioral and physiological responses to inflammatory stimuli administered either peripherally or centrally were evaluated. In the first study, twenty castrated male pigs were injected ip with 0, 0.5, 5, or 50 microg/kg BW lipopolysaccharide (LPS). Body temperature was monitored telemetrically, and serial blood samples were collected via an indwelling jugular catheter for determination of plasma cortisol and tumor necrosis factor-alpha (TNF-alpha) concentrations. Sickness behaviors were measured during 10-min tests at 0, 2, 4, 8, 12, and 24 h post injection. The 5 and 50 microg/kg doses of LPS increased plasma concentrations of cortisol and TNF-alpha, while inducing anorexia, hypersomnia, and fever. In contrast, although 0.5 microg/kg LPS induced acute anorexia, hypersomnia, and fever, it did not increase plasma TNF-alpha; and the cortisol response was small and transient, suggesting the behavioral system in pigs is more responsive to LPS than the hypothalamic-pituitary-adrenal (HPA) axis. Because LPS-induced behavior and activation of the HPA axis involve proinflammatory cytokines in the brain, in a second study, unrestrained pigs with jugular catheters were injected intracerebroventricularly (I.C.V.) with recombinant porcine TNF-alpha. Vehicle or TNF-alpha (0, 5, or 50 ng/kg) was injected I.C.V., and plasma cortisol and behavior were determined as before. Pigs injected I.C.V. with 50 ng/kg TNF-alpha showed anorexia, hypersomnia, and an abrupt increase in plasma cortisol concentration. Whereas 5 ng/kg TNF-alpha I.C.V. also induced marked sickness behavior, it failed to stimulate the HPA axis, as indicated by plasma cortisol levels. That there was a distinct difference in the magnitude of behavioral and endocrine responses to LPS and TNF-alpha suggests that different systems that are responsive to inflammatory stimuli exhibit different sensitivities.

Genomic mapping of chemokine and transforming growth factor genes in swine

Five chemokine genes, transforming growth factors alpha, beta 2 and 3 (TGFBA, TGFB-2, and TGFB-3), interleukin 8 (IL-8), and monocyte chemoattractant protein 2 (MCP-2), were mapped to porcine linkage groups on Chromosomes 3q, 10p, 7q, 8, and 12q, respectively. Restriction fragment length polymorphisms (RFLPs) for these genes were developed by Southern blot hybridization after digestion of porcine genomic DNA with BamHI and MspI (TGFBA), BamHI and PvuII (TGFB-2), HindIII (TGFB-3), BglII (IL-8), and PstI (MCP-2) and used to genotype the USDA-MARC Swine Reference Population pigs. Sufficient informative meioses, 61 (TGFBA), 58 (TGFB-2), 28 (TGFB-3), 38 (IL-8), and 156 (MCP-2), were available to pursue two-point pairwise linkage analysis with over 1,000 existing loci in the USDA-MARC genome database to establish initial linkage (LOD > 3). Multi-point analysis with CRIMAP determined the most likely order for each new marker. The assignment of the five chemokine genes in swine concurs with previous porcine/human chromosomal homologies based on results from ZOO-FISH and chromosomal painting experiments. These findings add five new informative Type I markers within a single gene family to the swine genome and may help us understand the genetic basis for disease resistance in livestock.

High-level secretion of two antibody single chain Fv fragments by Pichia pastoris

The diagnostic and therapeutic applications of antibody single-chain Fv (sFv) fragments often require large amounts of protein that can be problematic and expensive to obtain. Here we report the secretion of two sFv fragments by the yeast Pichia pastoris at levels up to 250 mg/l. Soluble sFv fragments were purified from culture supernatants in one step by affinity or metal-chelating chromatography, and were indistinguishable from their bacterially expressed counterparts in terms of affinity. Secretion of functional sFv fragments by Pichia pastoris provides a low cost, high yield alternative to current sFv expression systems.