Spontaneous immunological activities in the target tissue of vitiligo-prone Smyth and vitiligo-susceptible Brown lines of chicken

Introduction

Vitiligo is an acquired de-pigmentation disorder characterized by the post-natal loss of epidermal melanocytes (pigment-producing cells) resulting in the appearance of white patches in the skin. The Smyth chicken is the only model for vitiligo that shares all the characteristics of the human condition including: spontaneous post-natal loss of epidermal melanocytes, interactions between genetic, environmental and immunological factors, and associations with other autoimmune diseases. In addition, an avian model for vitiligo has the added benefit of an easily accessible target tissue (a growing feather) that allows for the repeated sampling of an individual and thus the continuous monitoring of local immune responses over time.

Methods

Using a combination of flow cytometry and gene expression analyses, we sought to gain a comprehensive understanding of the initiating events leading to expression of vitiligo in growing feathers by monitoring the infiltration of leukocytes and concurrent immunological activities in the target tissue beginning prior to visual onset and continuing throughout disease development.

Results

Here, we document a sequence of immunologically significant events, including characteristic rises in infiltrating B and αβ T cells as well as evidence of active leukocyte recruitment and cell-mediated immune activities (CCL19, IFNG, GZMA) leading up to visual vitiligo onset. Examination of growing feathers from vitiligo-susceptible Brown line chickens revealed anti-inflammatory immune activities which may be responsible for preventing vitiligo (IL10, CTLA4, FOXP3). Furthermore, we detected positive correlations between infiltrating T cells and changes in their T cell receptor diversity supporting a T cell-specific immune response.

Conclusion

Collectively, these results further support the notion of cell-mediated immune destruction of epidermal melanocytes in the pulp of growing feathers and open new avenues of study in the vitiligo-prone Smyth and vitiligo-susceptible Brown line chickens.

Integrative profiling of gene expression and chromatin accessibility elucidates specific transcriptional networks in porcine neutrophils

Neutrophils are vital components of the immune system for limiting the invasion and proliferation of pathogens in the body. Surprisingly, the functional annotation of porcine neutrophils is still limited. The transcriptomic and epigenetic assessment of porcine neutrophils from healthy pigs was performed by bulk RNA sequencing and transposase accessible chromatin sequencing (ATAC-seq). First, we sequenced and compared the transcriptome of porcine neutrophils with eight other immune cell transcriptomes to identify a neutrophil-enriched gene list within a detected neutrophil co-expression module. Second, we used ATAC-seq analysis to report for the first time the genome-wide chromatin accessible regions of porcine neutrophils. A combined analysis using both transcriptomic and chromatin accessibility data further defined the neutrophil co-expression network controlled by transcription factors likely important for neutrophil lineage commitment and function. We identified chromatin accessible regions around promoters of neutrophil-specific genes that were predicted to be bound by neutrophil-specific transcription factors. Additionally, published DNA methylation data from porcine immune cells including neutrophils were used to link low DNA methylation patterns to accessible chromatin regions and genes with highly enriched expression in porcine neutrophils. In summary, our data provides the first integrative analysis of the accessible chromatin regions and transcriptional status of porcine neutrophils, contributing to the Functional Annotation of Animal Genomes (FAANG) project, and demonstrates the utility of chromatin accessible regions to identify and enrich our understanding of transcriptional networks in a cell type such as neutrophils.

Evaluation of digestively resistant or soluble fibers, short- and medium-chain fatty acids, trace minerals, and antibiotics in nonchallenged nursery pigs on performance, digestibility, and intestinal integrity

Three experiments (EXP) were conducted to determine the effect of feed additives on performance, intestinal integrity, gastrointestinal volatile fatty acids (VFA), and energy and nutrient digestion in nonchallenged nursery pigs. In EXP 1, 480 pigs (6.36-kg body weight, BW) were placed into 96 pens with 5 pigs/pen, and allotted to 1 of 10 dietary treatments: 1) negative control containing no feed additive (NC), 2) NC + 44 mg chlortetracycline and 38.5 mg tiamulin/kg diet (CTsb), 3) NC + 5% resistant potato starch (RSpo), 4) NC + 5% soluble corn fiber (SCF), 5) NC + 5% sugar beet pulp (SBP), 6) NC + 0.30% fatty acid mix (FAM), 7) NC + 0.10% phytogenic blend of essential oils and flavoring compounds (PHY), 8) NC + 50 mg Cu and 1,600 mg zinc oxide/kg diet (CuZn), 9) NC + 5% resistant corn starch (RScn), and 10) NC + 0.05% β-glucan (BG) for 28 d. There was no impact of dietary treatment on BW gain or feed intake (P ≥ 0.22). Pigs fed diets containing SCF, CTsb, and RSpo resulted in microbial community differences compared to pigs fed the NC (P < 0.05). In EXP 2, 48 barrows (12.8 kg BW) were selected at the end of EXP 1 and fed the same dietary treatments they had previously received: 1) NC, 2) NC + 5% RScn, 3) NC + 5% SCF, and 4) NC + FAM for 8 d. There was no effect of feeding diets containing RScn, SCF, or FAM on in vivo intestinal permeability (P ≤ 0.21). Ileal or colon pH, concentrations of VFA did not differ due to dietary treatment (P ≥ 0.36), but pigs fed diets containing FAM resulted in a greater butyric acid concentration in the cecum compared to pigs fed the NC (P ≤ 0.05). In EXP 3, 156 pigs (6.11 kg BW) were placed into 52 pens with 3 pigs/pen and allotted to 1 of 4 dietary treatments arranged in a factorial manner: 1) NC, 2) NC + 5% RSpo, 3) NC + 0.30% FAM, and 4) NC + 5% RSpo + 0.30% FAM for 24 d. Feeding pigs diets containing RSpo did not affect BW gain (P = 0.91) while pigs fed diets containing FAM grew improved BW gain (P = 0.09). Colonic butyric acid concentrations were greater in pigs fed diets containing RSpo (P = 0.03), while pigs fed diets containing FAM exhibited reduced total VFA concentrations (P = 0.11). The results indicate that supplementing diets with digestively resistant but fermentable fibers, short- and medium-chain fatty acids, or antibiotics do not have a consistent effect, positive or negative, on markers of intestinal integrity or barrier function, intestinal VFA patterns, ATTD of energy and nutrients, or on pig performance.

Short Chain Fatty Acids and Bacterial Taxa Associated with Reduced Salmonella enterica serovar I 4,[5],12:i:- Shedding in Swine Fed a Diet Supplemented with Resistant Potato Starch

Salmonella enterica serovar I 4,[5],12:i:- is a foodborne pathogen of concern because many isolates are multidrug-resistant (resistant to ≥3 antimicrobial classes) and metal tolerant. In this study, three in-feed additives were individually tested for their ability to reduce Salmonella I 4,[5],12:i:- shedding in swine: resistant potato starch (RPS), high amylose corn starch, and a fatty acid blend, compared with a standard control diet over 21 days. Only RPS-fed pigs exhibited a reduction in Salmonella fecal shedding, different bacterial community compositions, and different cecal short chain fatty acid (SCFA) profiles relative to control animals. Within the RPS treatment group, pigs shedding the least Salmonella tended to have greater cecal concentrations of butyrate, valerate, caproate, and succinate. Additionally, among RPS-fed pigs, several bacterial taxa (Prevotella_7, Olsenella, and Bifidobacterium, and others) exhibited negative relationships between their abundances of and the amount of Salmonella in the feces of their hosts. Many of these same taxa also had significant positive associations with cecal concentrations of butyrate, valerate, caproate, even though they are not known to produce these SCFAs. Together, these data suggest the RPS-associated reduction in Salmonella shedding may be dependent on the establishment of bacterial cross feeding interactions that result in the production of certain SCFAs. However, directly feeding a fatty acid mix did not replicate the effect. RPS supplementation could be an effective means to reduce multidrug-resistant (MDR) S. enterica serovar I 4,[5],12:i:- in swine, provided appropriate bacterial communities are present in the gut. IMPORTANCE Prebiotics, such as resistant potato starch (RPS), are types of food that help to support beneficial bacteria and their activities in the intestines. Salmonella enterica serovar I 4,[5],12:i:- is a foodborne pathogen that commonly resides in the intestines of pigs without disease, but can make humans sick if unintentionally consumed. Here we show that in Salmonella inoculated pigs, feeding them a diet containing RPS altered the colonization and activity of certain beneficial bacteria in a way that reduced the amount of Salmonella in their feces. Additionally, within those fed RPS, swine with higher abundance of these types of beneficial bacteria had less Salmonella I 4,[5],12:i:- in their feces. This work illustrates likely synergy between the prebiotic RPS and the presence of certain gut microorganisms to reduce the amount of Salmonella in the feces of pigs and therefore reduce the risk that humans will become ill with MDR Salmonella serovar I 4,[5],12:i:-.

Immune Activities in Choroids of Visually Impaired Smyth Chickens With Autoimmune Vitiligo

Vitiligo is a common dermatological disorder affecting 1–2% of the world’s population. It is characterized by postnatal, autoimmune destructions of melanocytes in the skin, resulting in patches of depigmentation. Autoimmunity in vitiligo may also affect melanocytes in non-integumental tissues, including the eyes where choroidal melanocytes are the target of the autoimmune response. The Smyth line (SL) of chicken is the only animal model that spontaneously and predictably develops all clinical and biological manifestations of autoimmune vitiligo. In SL vitiligo (SLV), destruction of epidermal melanocytes in growing feathers (GFs) involves a melanocyte-specific, Th1-mediated cellular immune response. Smyth chickens may also exhibit uveitis and vision impairment. Previous studies established a strong association between SLV and vision impairment, including similar pathology in affected eyes and GFs. To determine the presence, types, and activities of choroid infiltrating mononuclear cells, we collected eyes before, near onset, and during active SLV from sighted, partially blind, and blind SL chickens. All SL chickens with vision impairment had SLV. Immunohistochemistry and quantitative reverse transcriptase-PCR analyses revealed mononuclear cell and cytokine expression profiles in the autoimmune destruction of melanocytes in choroids that are identical to those described in GF, demonstrating the systemic nature of autoimmunity against melanocytes in SLV. In addition, we observed aberrant melanogenesis in SL eyes. The immunopathogenesis in SL vision impairment resembles human vitiligo-associated ocular diseases, especially Vogt–Koyanagi–Harada syndrome and sympathetic ophthalmia. Hence, the Smyth chicken autoimmune vitiligo model provides the opportunity to expand our understanding of spontaneous autoimmune pigmentation disorders and to develop effective treatment strategies.

Development of swine immune reagents for analysis of immune correlates for vaccines, infection, and in biomedical research

The goal of the USDA-NIFA Swine Immune Toolkit Initiative has been to generate priority immune reagents based on inputs from veterinary immunology researchers worldwide, and pipeline them for marketing. So far in our efforts we express soluble proteins in yeast system and then produce panels of monoclonal antibodies (mAbs) using collaborations with commercial partners for protein expression and mAb production. So far we generated several new panels of mAbs reactive to porcine IL-6, IL-13, IFN-γ, IL-17A, IL-28B, CXCL10, and BAFF and screened their reactivity in multiple immune assays. Reactivity tests of labeled anti-IL-6 and anti-IL-13 mAbs for intracellular staining of porcine immune cells using flow cytometry assay are in progress. Our results have confirmed the reactivity of porcine IL-17A, IFN-γ and CXCL10 mAbs. A sensitive sandwich ELISA is now available for IL-17A, IL-13 and CXCL10; other targets are being screened for best mAb pairs for ELISA. Planning has been initiated for the generation of IL-5 and IL-21 mAbs; and use of SLA-I & -II tetramers to identify swine CD4 and CD8 T cells specific for influenza virus peptides. For each target, our goal is to provide the veterinary community with new commercial reagents and standardized assay techniques for their research efforts. Tools and reagents generated by this project will undoubtedly advance our understanding of swine immune responses to disease, vaccine and biomedical research efforts.

Supported by USDA-NIFA AFRI grant # 2019-67015-29815

Innate Memory Following Intravenous BCG in Neonatal Pigs

In adults and rodents, Bacillus Calmette-Guerin (BCG) inoculation alters innate immune cells via epigenetic and metabolic modifications resulting in heightened responses to subsequent microbial exposure (innate memory). Neonatal BCG vaccination can correlate to improved disease resistance in some human populations, but studies with human infants are extremely limited. Pigs are a relevant biomedical model for human disease and offer a path to directly asses neonatal innate memory to improve disease resilience. BCG administration in a weaned (3 week old) pig model elicited monocyte memory only with intravenous (IV) but not subcutaneous administration. Therefore, to evaluate induction of innate memory in neonates, 3–5 day old piglets received intravenous (IV) BCG or mock and ex vivo monocyte memory was assessed. At 3 and 6 weeks post-BCG, monocytes from the IV-BCG group had elevated TNF but not IL-1β production in response to LPS stimulation ex vivo, indicating neonatal BCG exposure induced innate memory. Interestingly, broncho-alveolar lavage cells from IV-BCG group had minimal differences compared to mock group in response to LPS, suggesting IV-BCG alters responses in peripheral monocytes differently than tissue resident myeloid-lineage cells. Overall, IV-BCG administration induced monocyte memory in neonatal pigs, highlighting piglets as a valuable model for continued study on the utility of BCG induced innate memory to improve disease resilience.

This work was funded by USDA-NIFA AFRI grant # 2019-07511 as part of the joint USDA-NIFA-NIH Dual Purpose with Dual Benefit: Research in Biomedicine and Agriculture Using Agriculturally Important Domestic Animal Species Program and USDA-ARS CRIS project 5030-32000-225-000D

Reference Transcriptomes of Porcine Peripheral Immune Cells Created Through Bulk and Single-Cell RNA Sequencing

Pigs are a valuable human biomedical model and an important protein source supporting global food security. The transcriptomes of peripheral blood immune cells in pigs were defined at the bulk cell-type and single cell levels. First, eight cell types were isolated in bulk from peripheral blood mononuclear cells (PBMCs) by cell sorting, representing Myeloid, NK cells and specific populations of T and B-cells. Transcriptomes for each bulk population of cells were generated by RNA-seq with 10,974 expressed genes detected. Pairwise comparisons between cell types revealed specific expression, while enrichment analysis identified 1,885 to 3,591 significantly enriched genes across all 8 cell types. Gene Ontology analysis for the top 25% of significantly enriched genes (SEG) showed high enrichment of biological processes related to the nature of each cell type. Comparison of gene expression indicated highly significant correlations between pig cells and corresponding human PBMC bulk RNA-seq data available in Haemopedia. Second, higher resolution of distinct cell populations was obtained by single-cell RNA-sequencing (scRNA-seq) of PBMC. Seven PBMC samples were partitioned and sequenced that produced 28,810 single cell transcriptomes distributed across 36 clusters and classified into 13 general cell types including plasmacytoid dendritic cells (DC), conventional DCs, monocytes, B-cell, conventional CD4 and CD8 αβ T-cells, NK cells, and γδ T-cells. Signature gene sets from the human Haemopedia data were assessed for relative enrichment in genes expressed in pig cells and integration of pig scRNA-seq with a public human scRNA-seq dataset provided further validation for similarity between human and pig data. The sorted porcine bulk RNAseq dataset informed classification of scRNA-seq PBMC populations; specifically, an integration of the datasets showed that the pig bulk RNAseq data helped define the CD4CD8 double-positive T-cell populations in the scRNA-seq data. Overall, the data provides deep and well-validated transcriptomic data from sorted PBMC populations and the first single-cell transcriptomic data for porcine PBMCs. This resource will be invaluable for annotation of pig genes controlling immunogenetic traits as part of the porcine Functional Annotation of Animal Genomes (FAANG) project, as well as further study of, and development of new reagents for, porcine immunology.

Characterization of circulating porcine immune cells using single-cell RNA-sequencing and comparison to human datasets

Pigs are part of global food security and serve as a valuable human biomedical model. Immunoreagent unavailability limits resolution of pig leukocyte populations by protein markers; thus, single-cell RNA-sequencing (scRNA) was used to characterize pig peripheral blood mononuclear cell (PBMC) populations and infer function based on transcriptional profiles and comparison to human datasets. Across seven PBMC samples partitioned and sequenced, 28,810 cells distributed across 36 clusters were classified into 13 general cell types including plasmacytoid dendritic cells (DC), conventional DCs, monocytes, more than ten B cell clusters including plasmablasts, conventional CD4 and CD8 αβ T cells, NK cells, and four clusters of γδ T cells. Signature gene sets for a publicly available human bulk RNA-seq dataset were assessed for relative enrichment in genes expressed in pig cells and substantial overlap in gene expression between specific pig and human PBMC populations was detected. Integration of pig scRNA with a public human scRNA dataset provided further validation for similarity between human and pig. Of four pig γδ T cell clusters, two had high prediction and mapping scores with human γδ T cells. The other two pig γδ T cell clusters had gene expression profiles predictive of human γδ T cells, but also human CD4 T central memory (Tcm) and innate lymphoid cells, suggesting innate and adaptive function of some pig γδ T cells. Pigs have a population of circulating double-positive (DP) CD4+CD8αα+ αβ T cells, and putative DP clusters had high prediction scores to human CD4 Tcm cells, supporting their classification in literature as memory cells. Overall, the data provided the first single-cell atlas for porcine PBMCs and comparison to human datasets.

Integrative profiling of chromatin accessibility and gene expression elucidate specific transcriptional network in porcine neutrophils

Pigs are an important component of global food security, and serve as a human biomedical model. Infectious diseases impact pig and human health and global food productivity. Components of the pig innate immune system, such as neutrophils, have not been fully described, and epigenetic mechanisms controlling gene expression remain unclear in pigs. We performed RNA- and assay for transposase-accessible chromatin (ATAC)-sequencing on two porcine neutrophil samples to characterize epigenetic regulation of gene expression in these differentiated cells. A deep neutrophil transcriptome detected expression of 10,974 genes. In comparison to previously reported RNA-seq data on eight sorted immune cell types from the same animals, we predicted 833 enriched (significantly higher and 2-fold higher than average across all other cell types) genes in neutrophils. The 833 gene list was significantly enriched for biological processes related to typical neutrophil functions using Gene Ontology and in comparison to human neutrophil RNA-seq data. ATAC-seq detected open chromatin (OP) regions from ~227 million total reads that identified on average 151,789 peaks located in intergenic (67%), intron (24%), promoter-TSS (6%), exon (3%) or TTS (1%) regions. OP regions whose signal is correlated with, and nearby to, genes with enriched neutrophil expression are being analyzed for sites predicted to be bound by transcription factors that could explain neutrophil-enriched expression patterns. The data reported here is the first integrative study of the epigenetics of porcine neutrophil gene expression and provide a valuable resource to elucidate neutrophil transcriptional regulatory networks.

Comparative annotation of porcine bone marrow cell types using scRNAseq

Pigs are important as a biomedical model and for worldwide meat production. Therefore, a better understanding of porcine hematopoiesis and immune system development could have a wide impact on human disease research and food production. The bone marrow represents a unique environment that is the major site of differentiation of stem cells and progenitors into mature blood cells. We performed scRNA-seq on bone marrow from healthy adult pigs and sequenced a total of 3,576 cells. After QC, 2,707 cells and 16,432 genes were used for downstream analysis. The porcine bone marrow cells were grouped into 15 distinct clusters and these relationships were mapped using non-linear dimensional reduction. To find markers that defined each cluster, we found a total of 3,335 differentially expressed genes using the non-parameteric Wilcoxon rank sum test. Further, pairwise differential expression testing and random forest models were used to evaluate the similarity between clusters and further define the unique features of each cluster. Using these defined markers, we were able to annotate the cell types for each cluster. The clusters represented a diverse set of cell types including myeloid and lymphoid cells, myeloid and lymphoid cell progenitors, and platelet and red blood cell progenitors. We validated these annotations using publicly available datasets including the CITE-seq database of human bone marrow mononuclear cells (Stuart et al., 2019). We also compared the expression profiles between similarly annotated cell types between human and pig. Our novel annotation of porcine bone marrow cells will be a resource for the study of porcine hematopoiesis and immune system development and help inform human translational biomedical research.

Innate and Adaptive Responses to Bacillus Calmette-Guerin in Young Pigs

Development of novel antibiotic alternatives is a critical One Health priority impacting both human and animal wellbeing. While the attenuated strain of M. bovis (Bacillus Calmette-Guerin, BCG) was developed as a vaccine against tuberculosis; recently, BCG has been observed to alter circulating monocytes leading to enhanced inflammatory immune responses to heterologous agonists. These changes can persist for months after the initial BCG exposure, and may serve to enhance innate immune health and reduce disease without the use of antibiotics. Following in vitro observation of innate training in pig monocytes, we wanted to study in vivo BCG responses in pigs as a potential path to enhance innate immunity. Young pigs were inoculated with BCG and weeks later ex vivo cytokine responses to innate TLR agonists and IFNγ response to M. bovis purified protein derivates (PPDb) were measured. PPDb stimulated PBMCs from pigs inoculated subcutaneous with 107 CFU of BCG produced the highest amount of IFNγ as compared to intramuscular inoculated or 106 CFU inoculated pigs. No differences were observed in PBMCs or monocytes stimulated ex vivo with TLR agonists between control and BCG inoculated pigs regardless of route or dose administered. Unlike cattle and humans, in pigs BCG does not seem to readily disseminate from the inoculation site, which may explain the lack of altered innate immune responses observed. Differences in adaptive immune responses indicated alterations to dose or route of BCG administration impacted immunogenicity. Future studies will employ intravenous BCG administration to understand if peripheral exposure to BCG is required to alter innate responses in circulating pig monocytes.

Differential induction of innate memory in porcine monocytes by -glucan or bacillus Calmette-Guerin

Innate immunomodulation via induction of innate memory is one mechanism to alter the host’s innate immune response to reduce or prevent disease. Microbial products modulate innate responses with immediate and lasting effects. Innate memory is characterized by enhanced (training) or depressed (tolerance) innate immune responses, including pro-inflammatory cytokine production, to secondary exposure following a priming event. To investigate the ability of β-glucans and bacillus Calmette-Guerin to induce innate training or tolerance in pig cells, porcine monocytes were cultured with priming agonist (β-glucans or bacillus Calmette-Guerin) then re-stimulated 5 d later with a heterologous microbial agonist to determine induction of innate memory. Priming with β-glucan from Saccharomyces cerevisiae depressed IL-1β and TNF-α cytokine responses to re-stimulation with LPS, indicative of a tolerized state. However, bacillus Calmette-Guerin priming induced a trained state in porcine monocytes, as LPS re-stimulation enhanced IL-1β and TNF-α gene expression and protein production. We present the first evidence of innate memory in pig monocytes, with bacillus Calmette-Guerin (training) or Saccharomyces cerevisiae β-glucan (tolerance). Induction of a trained or tolerized state in vitro is a first step to identify agonists to alter the innate immune system at the animal level with the intent of enhancing disease resistance.

Changes in H3K27ac at Gene Regulatory Regions in Porcine Alveolar Macrophages Following LPS or PolyIC Exposure

Changes in chromatin structure, especially in histone modifications (HMs), linked with chromatin accessibility for transcription machinery, are considered to play significant roles in transcriptional regulation. Alveolar macrophages (AM) are important immune cells for protection against pulmonary pathogens, and must readily respond to bacteria and viruses that enter the airways. Mechanism(s) controlling AM innate response to different pathogen-associated molecular patterns (PAMPs) are not well defined in pigs. By combining RNA sequencing (RNA-seq) with chromatin immunoprecipitation and sequencing (ChIP-seq) for four histone marks (H3K4me3, H3K4me1, H3K27ac and H3K27me3), we established a chromatin state map for AM stimulated with two different PAMPs, lipopolysaccharide (LPS) and Poly(I:C), and investigated the potential effect of identified histone modifications on transcription factor binding motif (TFBM) prediction and RNA abundance changes in these AM. The integrative analysis suggests that the differential gene expression between non-stimulated and stimulated AM is significantly associated with changes in the H3K27ac level at active regulatory regions. Although global changes in chromatin states were minor after stimulation, we detected chromatin state changes for differentially expressed genes involved in the TLR4, TLR3 and RIG-I signaling pathways. We found that regions marked by H3K27ac genome-wide were enriched for TFBMs of TF that are involved in the inflammatory response. We further documented that TF whose expression was induced by these stimuli had TFBMs enriched within H3K27ac-marked regions whose chromatin state changed by these same stimuli. Given that the dramatic transcriptomic changes and minor chromatin state changes occurred in response to both stimuli, we conclude that regulatory elements (i.e. active promoters) that contain transcription factor binding motifs were already active/poised in AM for immediate inflammatory response to PAMPs. In summary, our data provides the first chromatin state map of porcine AM in response to bacterial and viral PAMPs, contributing to the Functional Annotation of Animal Genomes (FAANG) project, and demonstrates the role of HMs, especially H3K27ac, in regulating transcription in AM in response to LPS and Poly(I:C).

Intraepithelial T Cells Diverge by Intestinal Location as Pigs Age

T cells resident within the intestinal epithelium play a central role in barrier integrity and provide a first line of immune defense. Intraepithelial T cells (IETs) are among the earliest immune cells to populate and protect intestinal tissues, thereby giving them an important role in shaping gut health early in life. In pigs, IETs are poorly defined, and their maturation in young pigs has not been well-studied. Given the importance of IETs in contributing to early life and long-term intestinal health through interactions with epithelial cells, the microbiota, and additional environmental factors, a deeper characterization of IETs in pigs is warranted. The objective of this study was to analyze age- and intestinal location-dependent changes in IETs across multiple sites of the small and large intestine in pigs between 4- and 8-weeks of age. IETs increased in abundance over time and belonged to both γδ and αβ T cell lineages. Similar compositions of IETs were identified across intestinal sites in 4-week-old pigs, but compositions diverged between intestinal sites as pigs aged. CD2⁺CD8α⁺ γδ T cells and CD4^-CD8α⁺ αβ T cells comprised >78% of total IETs at all intestinal locations and ages examined. Greater percentages of γδ IETs were present in large intestine compared to small intestine in older pigs. Small intestinal tissues had greater percentages of CD2⁺CD8α^- γδ IETs, while CD2⁺CD8α⁺ γδ IET percentages were greater in the large intestine. Percentages of CD4^-CD8α⁺ αβ IETs increased over time across all intestinal sites. Moreover, percentages of CD27⁺ cells decreased in ileum and large intestine over time, indicating increased IET activation as pigs aged. Percentages of CD27⁺ cells were also higher in small intestine compared to large intestine at later timepoints. Results herein emphasize 4- to 8-weeks of age as a critical window of IET maturation and suggest strong associations between intestinal location and age with IET heterogeneity in pigs.

Innate Immunomodulation in Food Animals: Evidence for Trained Immunity?

Antimicrobial resistance (AMR) is a significant problem in health care, animal health, and food safety. To limit AMR, there is a need for alternatives to antibiotics to enhance disease resistance and support judicious antibiotic usage in animals and humans. Immunomodulation is a promising strategy to enhance disease resistance without antibiotics in food animals. One rapidly evolving field of immunomodulation is innate memory in which innate immune cells undergo epigenetic changes of chromatin remodeling and metabolic reprogramming upon a priming event that results in either enhanced or suppressed responsiveness to secondary stimuli (training or tolerance, respectively). Exposure to live agents such as bacille Calmette-Guerin (BCG) or microbe-derived products such as LPS or yeast cell wall ß-glucans can reprogram or "train" the innate immune system. Over the last decade, significant advancements increased our understanding of innate training in humans and rodent models, and strategies are being developed to specifically target or regulate innate memory. In veterinary species, the concept of enhancing the innate immune system is not new; however, there are few available studies which have purposefully investigated innate training as it has been defined in human literature. The development of targeted approaches to engage innate training in food animals, with the practical goal of enhancing the capacity to limit disease without the use of antibiotics, is an area which deserves attention. In this review, we provide an overview of innate immunomodulation and memory, and the mechanisms which regulate this long-term functional reprogramming in other animals (e.g., humans, rodents). We focus on studies describing innate training, or similar phenomenon (often referred to as heterologous or non-specific protection), in cattle, sheep, goats, swine, poultry, and fish species; and discuss the potential benefits and shortcomings of engaging innate training for enhancing disease resistance.

Intraepithelial T cell phenotype and function diverge by intestinal location with age

Intestinal intraepithelial T cells (IETs) provide a first line of defense against intestinal pathogens and play an important role in immune tolerance versus activation. In pigs, intestinal T cell populations stabilize at ~8 weeks of age, but IET phenotypes and function are poorly understood during the early postnatal period. Better understanding age- and location-dependent characteristics of porcine IETs may be useful in developing strategies to maintain intestinal integrity and improve health. To assess impacts of age and intestinal location on abundance and composition of IETs, sections of jejunum, ileum, cecum, and colon from 4-, 6-, and 8-week-old pigs were analyzed by histologic staining and flow cytometric analyses. IET abundance increased with age, and CD2+CD8α+γδ and CD4−CD8α+αβ T cells were the primary IET populationsin all samples (&gt;78%). Compositions of IETs were similar at all locations in 4-week-old pigs. As pigs aged, cecal and colonic IET compositions remained similar to each other but diverged from small intestinal IETs, while jejunal and ileal IET compositions diverged from both large intestinal IETs and each other. These findings indicate both intestinal location and age are drivers of IET heterogeneity. Small intestinal IETs had lower percentages of γδ IETs in 6- and 8-week-old pigs, and CD4−CD8α+αβ IETs increased in abundance at all intestinal locations as pigs aged. Percentages of CD27+IETs in ileum and large intestine decreased over time, but decreases were more drastic in large intestine, suggesting IETs in the distal but not proximal intestinal tract were activated as pigs aged. Small intestinal IET compositions closely resembled human IET populations, highlighting pigs as a biomedical model for IET research.

The transcriptional landscape of porcine peripheral blood immune cells

Blood consists of different immune cells with essential functions given by distinct molecular signatures including transcriptomic profiles. The porcine immune system shares many similarities with that in human; however, the porcine immune cell transcriptome has not been as comprehensively studied. To identify distinct transcriptomic profiles of major porcine peripheral blood immune cells, we employed magnetic separation and fluorescence activated cell sorting methods to isolate 9 different cell types from blood PBMCs from two healthy pigs, representing monocytes, neutrophils, NK cells and specific populations of T and B cells. We obtained deep individual cell type transcriptomes using RNA-seq, detecting up to 10,974 genes. Principal component analysis revealed appropriate clustering of replicate samples and the separation of T, B, NK and myeloid cell groups. Pairwise comparisons revealed significant expression of a large number of genes specific for monocytes, neutrophils and NK cells only, while enrichment analysis identified highly differentially expressed genes for all cell types. Gene Ontology term analysis showed high enrichment of biological processes related to the nature of each cell type (i.e., B cell antigen presentation enriched in B cell transcriptome). The gene enrichment and specific genes of porcine immune cells is being further validated in silico to human datasets using gene set enrichment analysis (GSEA), and in vitro using qRT-PCR analysis. Taken together, the gene expression profiles reported here is the first comprehensive transcriptomic study of circulating porcine immune cell types and provides a valuable resource to elucidate molecular markers for porcine immune cell identity and function.

Dietary β-glucan reduced Salmonella shedding, shifted intestinal microbiome, and altered intestinal integrity

β-glucan is a prebiotic dietary fiber with immune and microbiota modulating properties. Dietary β-glucan can shift intestinal microbial populations and concentrations of short chain fatty acids (notably, butyrate and propionate), which may alter local populations of regulatory T-cells. Additionally, epigenetic reprograming of monocytes by β-glucan impacts subsequent monocyte responses to heterologous agonists, a form of innate training. Here, β-glucan from Saccharomyces cerevisiae was evaluated as a non-antibiotic dietary additive to limit shedding of the foodborne pathogen, Salmonella enterica server Typhimurium, via changes to the intestinal microbiota, intestinal integrity, and/or the local and peripheral immune system in pigs. Overall Salmonella shedding and cecal mucosa burden was significantly reduced in pigs fed dietary β-glucan compared to Salmonella challenged pigs on control diet. Shifts in microbial communities were associated with reduced Salmonella burden, as pigs fed β-glucan exhibited enhanced cecal epithelial barrier function, altered fecal bacterial communities, and increased short chain fatty acid concentrations. However, no significant differences in regulatory T cell population nor ex vivo monocyte responses were found between groups. Collectively, the non-antibiotic dietary additive β-glucan altered microbial communities and host epithelial cell function in conjunction with reduced Salmonella shedding in pigs.

Novel Engraftment and T Cell Differentiation of Human Hematopoietic Cells in ART-/-IL2RG-/Y SCID Pigs

Pigs with severe combined immunodeficiency (SCID) are an emerging biomedical animal model. Swine are anatomically and physiologically more similar to humans than mice, making them an invaluable tool for preclinical regenerative medicine and cancer research. One essential step in further developing this model is the immunological humanization of SCID pigs. In this work we have generated T- B- NK- SCID pigs through site directed CRISPR/Cas9 mutagenesis of IL2RG within a naturally occurring DCLRE1C (ARTEMIS)-/- genetic background. We confirmed ART-/-IL2RG-/Y pigs lacked T, B, and NK cells in both peripheral blood and lymphoid tissues. Additionally, we successfully performed a bone marrow transplant on one ART-/-IL2RG-/Y male SCID pig with bone marrow from a complete swine leukocyte antigen (SLA) matched donor without conditioning to reconstitute porcine T and NK cells. Next, we performed in utero injections of cultured human CD34+ selected cord blood cells into the fetal ART-/-IL2RG-/Y SCID pigs. At birth, human CD45+ CD3ε+ cells were detected in cord and peripheral blood of in utero injected SCID piglets. Human leukocytes were also detected within the bone marrow, spleen, liver, thymus, and mesenteric lymph nodes of these animals. Taken together, we describe critical steps forwards the development of an immunologically humanized SCID pig model.

β-glucan induced training and tolerance: alterations to primary monocytes

In mice and humans, exposure to β-glucan can induce epigenetic reprograming in monocytes resulting in enhanced responses to heterologous agonists. Epigenetic reprograming is the basis for innate memory, which includes both decreased immune responsiveness (innate tolerance) and increased responsiveness (innate training). As a valuable food animal and medically relevant species, we sought to understand the phenotypic and mechanistic alterations induced by β-glucan on swine cells to develop methods to enhance health while limiting antibiotic usage. Thus, primary porcine monocytes were stimulated with β-glucan from S. cerevisiae or C. albicans, rested for 5 d, and then restimulated with lipopolysaccharide (LPS; TLR 4 agonist) or Pam3CSK4 (synthetic triacylated lipopeptide; TLR 2 agonist) to determine trained or tolerant phenotype (increase or decrease in cytokine production relative to unstimulated controls). Zymosan (β-glucan from S. cerevisiae) primed monocytes exhibited a tolerant phenotype (decreased IL-1β and TNF-α production compared to controls) when restimulated with LPS or Pam3CSK4. However, β-glucan from C. albicans (the primary β-glucan used in mouse and human studies) primed porcine monocytes for increased cytokine production after LPS and Pam3CSK4 stimulation, an indication of trained immunity. Epigenetic analysis of the accessibility of the genome to transposase (ATAC-sequencing) showed changes in promoter peaks with treatment, providing insight into mechanisms of tolerance versus training. These data indicate that β-glucan can induce both training and tolerance in porcine monocytes, but the source and purity of β-glucan likely impacts innate memory.

Zymosan tolerizes primary pig monocytes to lipopolysaccharide stimulation

Exposure of monocytes to β-1,3 glucans from yeast cell wall can enhance the immune response to heterologous innate agonists, a phenomenon termed innate training. This is in contrast to tolerance, which is well described in relation to lipopolysaccharide (LPS) responses. Yeast extracts are fed to food animals for production and immune benefits, but the mechanism of immune modulation provided by dietary yeast is not clearly defined. With the recent limitations to antibiotic use in food production animals, alternatives are sought to maintain animal health and production. To elucidate the immunological effect of yeast β-glucans on swine monocytes when re-exposed to a heterologous agonist, we primed primary swine monocytes with varying amounts and sources of β-glucan for 24h in vitro and restimulated the cells 5d later to LPS. Monocytes primed with media only or LPS, and exposed to LPS 5d later, served as controls to delineate trained versus tolerant responses. Swine monocytes primed with LPS produced IL-1β and TNF-α, and transitioned to a tolerant state, with decreased production of IL-1β and TNF-α upon re-stimulation with LPS. Interestingly, monocytes primed with the commercial β-glucan, zymosan (S. cerevisiae), at 10mg/mL or higher and restimulated with LPS exhibited a tolerized state. Specifically, zymosan primed cells did not produce IL-1β or TNF-α in response to LPS restimulation. Monocytes primed with laminarin (L. digitata) and restimulated with LPS did not exhibit a trained or tolerant state. These data indicate that dosage and source of β-glucan play an important role in the priming of monocytes to secondary LPS exposure, and warrants further study to elucidate differential responses as they relate to commercial dietary β-glucans.

Gene expression profiling of muscle tissue in Brahman steers during nutritional restriction

Expression profiling using microarrays allows for the detailed characterization of the gene networks that regulate an animal's response to environmental stresses. During nutritional restriction, processes such as protein turnover, connective tissue remodeling, and muscle atrophy take place in the skeletal muscle of the animal. These processes and their regulation are of interest in the context of managing livestock for optimal production efficiency and product quality. Here we expand on recent research applying complementary DNA (cDNA) microarray technology to the study of the effect of nutritional restriction on bovine skeletal muscle. Using a custom cDNA microarray of 9,274 probes from cattle muscle and s.c. fat libraries, we examined the differential gene expression profile of the LM from 10 Brahman steers under three different dietary treatments. The statistical approach was based on mixed-model ANOVA and model-based clustering of the BLUP solutions for the gene x diet interaction effect. From the results, we defined a transcript profile of 156 differentially expressed array elements between the weight loss and weight gain diet substrates. After sequence and annotation analyses, the 57 upregulated elements represented 29 unique genes, and the 99 downregulated elements represented 28 unique genes. Most of these co-regulated genes cluster into groups with distinct biological function related to protein turnover and cytoskeletal metabolism and contribute to our mechanistic understanding of the processes associated with remodeling of muscle tissue in response to nutritional stress.

Gene expression profiling of bovine skeletal muscle in response to and during recovery from chronic and severe undernutrition1

Gene expression profiles of LM from beef cattle that underwent significant postweaning undernutrition were studied using complementary DNA (cDNA) microarrays. After 114 d of undernutrition, the RNA from LM showed 2- to 6-fold less expression of many genes from the classes of muscle structural proteins, muscle metabolic enzymes, and extracellular matrix compared with animals on a rapid growth diet. The expression levels of these genes had mostly returned to pretreatment levels after 84 d of realimentation. The gene expression changes associated with undernutrition and BW loss showed an emphasis on downregulation of gene expression specific to fast-twitch fibers, typical of starving mammals, with a preferential atrophy of glycolytic fast-twitch fibers. We also identified a small group of genes that showed 2- to 5-fold elevated expression in LM after 114 d of undernutrition. Putative roles for these genes in atrophying skeletal muscle are regulation of myogenic differentiation (CSRP3), maintenance of mesenchymal stem cells (CYR61), modulation of membrane function (TM4SF2), prevention of oxidative damage (SESN1), and regulation of muscle protein degradation (SQSTM1). A significant increase in stearoyl-CoA desaturase (SCD) gene expression was observed in atrophying muscle, suggesting either that increased fatty acid synthesis is part of the tissue response to caloric restriction, or that SCD plays another role in energy metabolism in the mixed cellular environment of bovine skeletal muscle.

Joint analysis of multiple cDNA microarray studies via multivariate mixed models applied to genetic improvement of beef cattle

In functional genomic laboratories, it is common to use the same microarray slide across studies, each investigating a unique biological question, and each analyzed separately due to computational limitations and/or because there is no hybridization of samples from different studies on one slide. However, the question of analyzing data from multiple studies is a major current issue in microarray data analysis because there are gains to be made in the accuracy of estimated effects by exploiting a covariance structure between gene expression data across studies. We propose an approach for combining multiple studies using multivariate mixed models, with the assumption of a nonzero correlation among genes across experiments, while imposing a null residual covariance. We applied this method to jointly analyze three experiments in genetics of cattle with a total of 54 arrays, each with 19,200 spots and 7,638 elements. The resulting seven-variate model contains 752,476 equations and 56 covariances. To identify differentially expressed genes, we applied model-based clustering to a linear combination of the random gene x variety interaction effect. We enhanced the biological interpretation of the results by applying an iterative algorithm to identify the gene ontology classes that significantly changed in each experiment. We found 118 elements with coordinate expression that clustered into distinct biological functions such as adipogenesis and protein turnover. These results contribute to our understanding of the mechanistic processes involved in adipogenesis and nutrient partitioning.

Heterozygosity, inbreeding and neonatal traits in Soay sheep on St Kilda

We investigated whether birth weight and neonatal survival, a period within which 24% of all mortalities occur, were correlated with levels of inbreeding in St Kilda Soay sheep, using pedigree inbreeding coefficients and four marker-based estimators of inbreeding. None of the inbreeding estimators, either of the offspring, or of their mothers, explained significant variation in a lamb's birth weight or probability of surviving the neonatal period, suggesting low inbreeding depression for these traits. We evaluated the correlation between the marker-based measures of inbreeding and inbreeding coefficients obtained from the Soay pedigree, where paternal links were inferred using the same panel of microsatellite markers. Even when using a relatively complete portion of the pedigree, in which all individuals had known maternal and paternal grandparents, the correlation was found to be weak (r = -0.207, where mean f = 0.0168). These results add support to the recent prediction that when the mean and variance in inbreeding are low in a population, heterozygosity-fitness correlations can be very weak or even undetectable. The pursuit of more detailed pedigrees offers the best prospect for identifying inbreeding depression within this study population.

Maternal genetic effects set the potential for evolution in a free-living vertebrate population

Heritable maternal effects have important consequences for the evolutionary dynamics of phenotypic traits under selection, but have only rarely been tested for or quantified in evolutionary studies. Here we estimate maternal effects on early-life traits in a feral population of Soay sheep (Ovis aries) from St Kilda, Scotland. We then partition the maternal effects into genetic and environmental components to obtain the first direct estimates of maternal genetic effects in a free-living population, and furthermore test for covariance between direct and maternal genetic effects. Using an animal model approach, direct heritabilities (h2) were low but maternal genetic effects (m2) represented a relatively large proportion of the total phenotypic variance for each trait (birth weight m2=0.119, birth date m2=0.197, natal litter size m2=0.211). A negative correlation between direct and maternal genetic effects was estimated for each trait, but was only statistically significant for natal litter size (ram= -0.714). Total heritabilities (incorporating variance from heritable maternal effects and the direct-maternal genetic covariance) were significant for birth weight and birth date but not for natal litter size. Inadequately specified models greatly overestimated additive genetic variance and hence direct h2 (by a factor of up to 6.45 in the case of birth date). We conclude that failure to model heritable maternal variance can result in over- or under-estimation of the potential for traits to respond to selection, and advocate an increased effort to explicitly measure maternal genetic effects in evolutionary studies.

A mixture model-based cluster analysis of DNA microarray gene expression data on Brahman and Brahman composite steers fed high-, medium-, and low-quality diets

The objective of this study is to explore aspects of the statistical analysis of gene expression response at the muscle tissue level to varying levels of energy and protein in the diet. Eleven Brahman and Brahman composite steers (weighing 302 +/- 9.8 kg, on average) were allocated randomly into high- (HIGH), medium- (MED), and low- (LOW) quality forage diets for 27 d. After this period, a biopsy of the longissimus dorsi muscle was taken from each animal and total RNA was extracted to generate the labeled target for microarray experimentation. These targets were hybridized to a complementary DNA (cDNA) microarray of 9,274 probes from cattle muscle and subcutaneous fat cDNA libraries. After edits, 151,904 expression intensity levels of 4,747 genes were analyzed. Emphasis was given to the choice of power transformation of the intensity channel readings and to the consistency of readings within each diet quality group. The statistical approach to isolate differentially expressed genes was based on model-based clustering via a mixture of normal distributions estimated through maximal likelihood. The base-2 logarithm was found to be the optimal power transformation to normalize gene intensity levels. A two-sample t-statistic was defined as a measure of possible differential expression. For each of the three diet contrasts, HIGH vs. LOW, HIGH vs. MED, and MED vs. LOW, three clusters were found, two of which contained more than 94% genes with almost no altered gene expression levels, whereas the third cluster contained the remaining genes with a differential expression. Results from the HIGH vs. LOW contrast identified 27 genes with a greater than 95% posterior probability of belonging to the cluster of differentially expressed genes.

Isolation of a cDNA encoding a putative cellulase in the red claw crayfish Cherax quadricarinatus

Amino acid sequences of cellulases have been determined in insects, nematodes, plants, slime moulds and bacteria but not in crustaceans. However, cellulase activity has been demonstrated in the hepatopancreas of the red claw crayfish, Cherax quadricarinatus. In order to obtain information on the nature of this cellulase, a C. quadricarinatus hepatopancreas cDNA library was screened with a PCR product generated using degenerate oligonucleotide primers derived from conserved regions of known cellulases. Two identical 1.56kb cDNAs with sequence similarities to known cellulases, particularly the termite endoglucanases, were identified and sequenced. The clones contain the complete cDNA open reading frame for an endo-1, 4-beta-glucanase of 469 amino acids termed Cherax quadricarinatus endoglucanase (CqEG). The endogenous origin of the gene was confirmed by PCR amplification and sequencing of a 1012bp PCR product from genomic DNA. This fragment contains four exon sequences identical to the cDNA and is interrupted by three introns of 371, 102, 194bp respectively, with one intron exhibiting typical eukaryotic splice sites. The isolation of an endo-1,4-beta-glucanase encoding cDNA from the crayfish C. quadricarinatus provides the first endogenous cellulase sequence in a crustacean species.

Genome organization and transcription strategy in the complex GNS-L intergenic region of bovine ephemeral fever rhabdovirus

A 1622 nucleotide region of the bovine ephemeral fever virus (BEFV) genome, located between the second glycoprotein (GNS) gene and the polymerase (L) gene, has been cloned and sequenced in Australian (BB7721) and Chinese (Beijing-1) isolates of the virus. In the Australian isolate, the region contains five long open reading frames (ORFs) organized into three coding regions (alpha, beta and gamma), each of which are bound by a consensus transcription initiation and transcription termination-polyadenylation-like sequences. The alpha coding region contains three long ORFs (alpha 1, alpha 2 and alpha 3). The alpha 1 ORF encodes a 10.6 kDa polypeptide which contains hydrophobic and highly basic regions characteristic of a viroporin. The alpha 2 ORF encodes a 13.7 kDa polypeptide and overlaps the alpha 3 ORF which encodes a 5.7 kDa polypeptide. The beta coding region contains a single long ORF encoding a polypeptide of 12.2 kDa. The gamma coding region, which does not occur in Adelaide River virus (ARV), contains a single long ORF encoding a polypeptide of 13.4 kDa. The Chinese isolate shares 91% nucleotide sequence identity with the Australian isolate. The organization of the alpha, beta and gamma coding regions is preserved and the sequences of the encoded polypeptides are similar to those of BB7721. The major transcription products of the region were identified in BB7721 as polycistronic alpha (alpha 1-alpha 2-alpha 3) and beta-gamma mRNAs. Sequence similarities in the BEFV alpha-beta and beta-gamma gene junctions, and the gamma-L and beta-L gene junctions of BEFV and ARV, suggest that the gamma gene may have evolved from the beta-gene by sequence duplication.

Effective vaccination of cattle using the virion G protein of bovine ephemeral fever virus as an antigen

In a series of experiments, the envelope glycoprotein (G protein) of bovine ephemeral fever virus (BEFV) induced immunity against challenge with virulent virus. Protection correlated with the level of specific serum antibodies to G protein measured by a blocking ELISA test and with the level of neutralizing antibody. The optimum vaccination regimen consisted of two injections given 21 days apart at a dose rate of 0.32 microgram per cow of purified G protein emulsified in the adjuvant Quil A. This schedule conferred immunity for the duration of the preliminary experiment (46 days). Immunity to severe disease, but not to infection, remained for at least 12 months after vaccination, although BEFV could not be reisolated from vaccinated cattle following challenge. Unvaccinated cattle used as controls exhibited typical signs of clinical ephemeral fever and BEFV was recovered from all control animals following challenge.

Effective vaccination of cattle using the virion G protein of bovine ephemeral fever virus as an antigen

In a series of experiments, the envelope glycoprotein (G protein) of bovine ephemeral fever virus (BEFV) induced immunity against challenge with virulent virus. Protection correlated with the level of specific serum antibodies to G protein measured by a blocking ELISA test and with the level of neutralizing antibody. The optimum vaccination regimen consisted of two injections given 21 days apart at a dose rate of 0.32 microgram per cow of purified G protein emulsified in the adjuvant Quil A. This schedule conferred immunity for the duration of the preliminary experiment (46 days). Immunity to severe disease, but not to infection, remained for at least 12 months after vaccination, although BEFV could not be reisolated from vaccinated cattle following challenge. Unvaccinated cattle used as controls exhibited typical signs of clinical ephemeral fever and BEFV was recovered from all control animals following challenge.

The genome of bovine ephemeral fever rhabdovirus contains two related glycoprotein genes

A 3789 nucleotide region of the bovine ephemeral fever virus (BEFV) genome, located 1.65 kb downstream of the N gene, has been cloned and sequenced. The region contains two long open reading frames (ORFs) which are bounded by putative consensus (AACAGG) and polyadenylation (CATG[A]7) sequences and are separated by an intergenic region of 53 nucleotides. Discrete mRNAs corresponding to each ORF have been identified. The first ORF encodes a polypeptide comprising 623 residues which was identified by peptide sequencing as the virion G protein. The deduced amino acid sequence of the G protein includes putative signal and transmembrane domains and five potential glycosylation sites. The second ORF encodes a polypeptide of 586 amino acids which also has characteristics of a rhabdovirus glycoprotein, including putative signal and transmembrane domains and eight potential glycosylation sites, and appears to correspond to a 90-kDa nonstructural glycoprotein (GNS) identified in BEFV-infected cells (Walker et al. [1991] J. Gen. Virol. 72, 67-74). A database search indicated that both the G and GNS proteins share significant amino acid sequence homology with other rhabdovirus G proteins and with each other. Highest homology scores for each protein were with sigma virus and vesicular stomatitis virus serotypes.

Fungal keratitis in Saudi Arabia

We studied a total of 27 cases of fungal keratitis is Saudi Arabia. History of trauma was found in 9 patients, and previous use of topical steroids in 6 patients. In the majority of patients the onset of the disease was in fall and spring. The most frequent cause of fungal keratitis was found to be Aspergillus spp., and these were isolated from 11 cases (41%). Eight of the 11 isolates were Aspergillus flavus. Other causes of keratomycosis included: Fusarium, Candida, and Mycelia sterilia. All patients were treated with antifungal therapy and 18 patients required surgical intervention. Vision improved among 11 patients, remained the same in 4 patients, and deteriorated after treatment in 6 patients. (6 patients failed to return for follow-up.) Four of the 27 patients developed fungal endophthalmitis. The high prevalence of Aspergillus spp. may be due to the fact that spores of Aspergillus can survive the hot and dry weather of Saudi Arabia.

Proteins of bovine ephemeral fever virus

The proteins of bovine ephemeral fever virus (BEFV) were examined in purified virions and in infected BHK-21 cells. Five structural proteins were named L (180K), G (81K), N (52K), M1 (43K) and M2 (29K). The 81K G protein incorporated [3H]glucosamine, was removed from virions by treatment with Triton X-100 and bound monoclonal antibodies which were both neutralizing and protective. Treatment of virions with Triton X-100 and 0.2 to 1.0 M-NaCl progressively released L, M1 and M2. The N protein remained associated with nucleocapsids in up to 2.5 M-NaCl. The glycoprotein (G), nucleoprotein (N) and matrix protein (M2) were phosphorylated. In BEFV-infected BHK-21 cells, five virus-induced proteins were detected from 12 h post-infection. The L, N, M1 and M2 proteins corresponded to those detected in virions whereas the G protein existed in two forms. In tunicamycin-treated cells these occurred as 67K and 71K non-glycosylated precursors. In the absence of tunicamycin, 77K and 79K glycosylated forms were further modified to produce the 81K virion G protein and a 90K cell-associated form. Five viral proteins were also detected in cells infected with the closely related Berrimah virus; the Berrimah virus G protein was also present in two forms.

Mapping of antigenic sites on the bovine ephemeral fever virus glycoprotein using monoclonal antibodies

Monoclonal antibodies (MAbs) were produced against the G, M2 and N proteins of bovine ephemeral fever virus (BEFV) and 29 were selected for further study. Thirteen neutralizing MAbs were assigned to one conformation-independent and at least two conformation-dependent antigenic sites on the G protein by a competitive binding ELISA. The panel of MAbs were tested by neutralization and immunofluorescence with three strains of BEFV and three BEFV-related viruses. The results indicated that BEFV strains from different sources were not identical and that the M2 protein was the least variable of the proteins investigated. Passive protection studies in mice showed that the correlation between neutralizing titre and resistance to challenge was 0.85 (P less than 0.001).

Goblet cell population among patients with inactive trachoma

Trachoma is a chlamydial disease that affects millions of people each year, particularly in developing countries. In the chronic phase, inflammation causes scarring of the conjunctiva followed by dry eye which can result in blindness. Trachoma may cause dryness of the eye by decreasing mucus production and aqueous secretions. Conjunctival impression cytology was carried out to determine the goblet cell population among patients with trachoma. We performed impression cytology on 32 patients with inactive trachoma and 31 age and sex matched controls. Impression cytology showed that the nasal conjunctiva contains the greatest number of goblet cells. Trachoma patients with severe scarring had significantly less goblet cell counts than those with mild scarring (p less than 0.05). In the group of ten patients with severe trachoma and keratinization, there was marked reduction or absence of goblet cells. Trachoma appears to initiate a viscious cycle of conjunctival scarring, mucus deficiency, and chronic conjunctival inflammation.