Generation of transgenic cattle expressing human β-defensin 3 as an approach to reducing susceptibility toMycobacterium bovisinfection

Outlook on genome editing application to cattle

In livestock industry, there is growing interest in methods to increase the production efficiency of livestock to address food shortages, given the increasing global population. With the advancements in gene engineering technology, it is a valuable tool and has been intensively utilized in research specifically focused on human disease. In historically, this technology has been used with livestock to create human disease models or to produce recombinant proteins from their byproducts. However, in recent years, utilizing gene editing technology, cattle with identified genes related to productivity can be edited, thereby enhancing productivity in response to climate change or specific disease instead of producing recombinant proteins. Furthermore, with the advancement in the efficiency of gene editing, it has become possible to edit multiple genes simultaneously. This cattle breed improvement has been achieved by discovering the genes through the comprehensive analysis of the entire genome of cattle. The cattle industry has been able to address gene bottlenecks that were previously impossible through conventional breeding systems. This review concludes that gene editing is necessary to expand the cattle industry, improving productivity in the future. Additionally, the enhancement of cattle through gene editing is expected to contribute to addressing environmental challenges associated with the cattle industry. Further research and development in gene editing, coupled with genomic analysis technologies, will significantly contribute to solving issues that conventional breeding systems have not been able to address.

Perspectives in Genome-Editing Techniques for Livestock

Genome editing of farm animals has undeniable practical applications. It helps to improve production traits, enhances the economic value of livestock, and increases disease resistance. Gene-modified animals are also used for biomedical research and drug production and demonstrate the potential to be used as xenograft donors for humans. The recent discovery of site-specific nucleases that allow precision genome editing of a single-cell embryo (or embryonic stem cells) and the development of new embryological delivery manipulations have revolutionized the transgenesis field. These relatively new approaches have already proven to be efficient and reliable for genome engineering and have wide potential for use in agriculture. A number of advanced methodologies have been tested in laboratory models and might be considered for application in livestock animals. At the same time, these methods must meet the requirements of safety, efficiency and availability of their application for a wide range of farm animals. This review aims at covering a brief history of livestock animal genome engineering and outlines possible future directions to design optimal and cost-effective tools for transgenesis in farm species.

Generation of double knockout cattle via CRISPR-Cas9 ribonucleoprotein (RNP) electroporation

BACKGROUND

Genome editing has been considered as powerful tool in agricultural fields. However, genome editing progress in cattle has not been fast as in other mammal species, for some disadvantages including long gestational periods, single pregnancy, and high raising cost. Furthermore, technically demanding methods such as microinjection and somatic cell nuclear transfer (SCNT) are needed for gene editing in cattle. In this point of view, electroporation in embryos has been risen as an alternative.

RESULTS

First, editing efficiency of our electroporation methods were tested for embryos. Presence of mutation on embryo was confirmed by T7E1 assay. With first combination, mutation rates for MSTN and PRNP were 57.6% ± 13.7% and 54.6% ± 13.5%, respectively. In case of MSTN/BLG, mutation rates were 83.9% ± 23.6% for MSTN, 84.5% ± 18.0% for BLG. Afterwards, the double-KO embryos were transferred to surrogates and mutation rate was identified in resultant calves by targeted deep sequencing. Thirteen recipients were transferred for MSTN/PRNP, 4 calves were delivered, and one calf underwent an induction for double KO. Ten surrogates were given double-KO embryos for MSTN/BLG, and four of the six calves that were born had mutations in both genes.

CONCLUSIONS

These data demonstrated that production of genome edited cattle via electroporation of RNP could be effectively applied. Finally, MSTN and PRNP from beef cattle and MSTN and BLG from dairy cattle have been born and they will be valuable resources for future precision breeding.

The relationship between host defense peptides and adrenal steroids. An account of reciprocal influences

AIM

β-defensins 2 and -3 (HBD-2 and HBD-3) and cathelicidin LL-37 are host defense peptides (HDPs) that play a crucial role in the immune response against mycobacteria. Given our former studies in tuberculosis patients wherein their plasma levels of such peptides correlated with steroid hormone concentrations, we now studied the reciprocal influence of cortisol and/or dehydroepiandrosterone (DHEA) on HDPs biosynthesis and LL-37 on adrenal steroidogenesis.

MAIN METHODS

Cultures of macrophages derived from the THP-1 line were treated with cortisol (10^-6M) and/or DHEA (10^-6M and 10^-7M) and stimulated with irradiated M. tuberculosis (Mi) or infected M. tuberculosis strain H37Rv to assess cytokine production, HDPs, reactive oxygen species (ROS) and colony forming units. Cultures of NCI-H295-R adrenal line were treated with LL37 (5, 10, and 15 µg/ml) for 24 h to further measure cortisol and DHEA levels together with steroidogenic enzyme transcripts.

KEY FINDINGS

In macrophages, M. tuberculosis produced an increase of IL-1β, TNFα, IL-6, IL-10, LL-37, HBD-2, and HBD-3 levels, irrespective of DHEA treatment. Adding cortisol to M. tuberculosis-stimulated cultures (with or without DHEA) decreased the amounts of these mediators, compared to only stimulated cultures. Although M. tuberculosis reduced ROS levels, DHEA increased these values in addition to diminishing intracellular mycobacterial growth (no matter cortisol treatment). In turn, studies on adrenal cells showed that LL-37 reduced the production of cortisol and DHEA besides modifying transcripts for some steroidogenic enzymes.

SIGNIFICANCE

while adrenal steroids seem to influence the production of HDPs, the former compounds are also likely to modulate adrenal biogenesis.

Vitamin D induced microbicidal activity against Mycobacterium bovis BCG is dependent on the synergistic activity of bovine peripheral blood cell populations

A growing appreciation is emerging of the beneficial role of vitamin D for health and resistance against infectious diseases, including tuberculosis. However, research has predominantly focused on murine and human species and functional data in bovines is limited. Therefore, the objective of this study was to assess the microbicidal activity and immunoregulatory effect of the vitamin D metabolite 1,25(OH)2D3 on bovine peripheral blood leukocytes (PBL) in response to Mycobacterium bovis BCG (BCG) infection using a combination of functional assays and gene expression profiling. Blood from Holstein-Friesian bull calves with low circulating levels of 25(OH)D was stimulated with 1,25(OH)2D3 for 2 h, and then infected with M. bovis BCG. Results showed that 1,25(OH)2D3 supplementation significantly increased BCG killing by on average 16 %, although responses varied between 1 % and 38 % killing. Serial cell subset depletion was then performed on PBL prior to 1,25(OH)2D3 incubation and BCG infected as before to analyse the contribution of major cell types to mycobacterial growth control. Specific antibodies and either magnetic cell separation or density gradient centrifugation of monocytes, granulocytes, CD3+, CD4+, and CD8+ T lymphocytes were used to capture each cell subset. Results showed that depletion of granulocytes had the greatest impact on BCG growth, leading to a significant enhancement of bacterial colonies. In contrast, depletion of CD4+ or CD8+ T cells individually, or in combination (CD3+), had no impact on mycobacterial growth control. In agreement with our previous data, 1,25(OH)2D3 significantly increased bacterial killing in PBL, in monocyte depleted samples, and a similar trend was observed in the granulocyte depleted subset. In addition, specific analysis of sorted neutrophils treated with 1,25(OH)2D3 showed an enhanced microbicidal activity against both BCG and a virulent strain of M. bovis. Lastly, data showed that 1,25(OH)2D3 stimulation increased reactive oxygen species (ROS) production and the expression of genes encoding host defence peptides (HDP) and pathogen recognition receptors (PRRs), factors that play an important role in the microbicidal activity against mycobacteria. In conclusion, the vitamin D metabolite 1,25(OH)2D3 improves antimycobacterial killing in bovine PBLs via the synergistic activity of monocytes and granulocytes and enhanced activation of innate immunity.

Animal Transgenesis and Cloning: Combined Development and Future Perspectives

The revolution in animal transgenesis began in 1981 and continues to become more efficient, cheaper, and faster to perform. New genome editing technologies, especially CRISPR-Cas9, are leading to a new era of genetically modified or edited organisms. Some researchers advocate this new era as the time of synthetic biology or re-engineering. Nonetheless, we are witnessing advances in high-throughput sequencing, artificial DNA synthesis, and design of artificial genomes at a fast pace. These advances in symbiosis with animal cloning by somatic cell nuclear transfer (SCNT) allow the development of improved livestock, animal models of human disease, and heterologous production of bioproducts for medical applications. In the context of genetic engineering, SCNT remains a useful technology to generate animals from genetically modified cells. This chapter addresses these fast-developing technologies driving this biotechnological revolution and their association with animal cloning technology.

Secretion of IFN-γ by Transgenic Mammary Epithelial Cells in vitro Reduced Mastitis Infection Risk in Goats

Mastitis results in great economic loss to the dairy goat industry. Many approaches have attempted to decrease the morbidity associated with this disease, and among these, transgenic strategy have been recognized as a potential approach. A previous mammalian study reports that interferon-gamma (IFN-γ) has potential anti-bacterial bioactivity against infection in vitro; however, its capacity in vivo is ambiguous. In this study, we initially constructed targeting and homologous recombination vectors (containing the IFN-γ gene) and then transferred the vectors into goat mammary gland epithelial cells (GMECs). Enzyme digestion and sequencing analysis indicated that the vectors used in this study were built correctly. Subsequently, monoclonal cells were selected using puromycin and the polymerase chain reaction (PCR) test indicated that IFN-γ was correctly inserted downstream of the casein promoter. Monoclonal cells were then assessed for reducible expression, and reverse transcriptase-PCR (RT-PCR) and Western blot tests confirmed that monoclonal cells could express IFN-γ. Finally, anti-bacterial capacity was evaluated using bacterial counts and flow cytometry analysis. Decreased bacterial counts and cell apoptosis rates in transgenic GMECs demonstrated that the secretion of IFN-γ could inhibit bacterial proliferation. Therefore, IFN-γ gene transfection in goat mammary epithelial cells could inhibit bacterial proliferation and reduce the risk of mammary gland infection in goats.

Host Serum Proteins as Potential Biomarkers of Bovine Tuberculosis Resistance Phenotype

Eradication of bovine tuberculosis (bTB) continues to be a worldwide challenge. The lack of reliable vaccines dampens the control and eradication programs of Mycobacterium bovis infection and spread. Selection and breeding of cattle resistant to M. bovis infection would greatly enhance the effectiveness of bTB eradication programs. Here, we have evaluated the potential of serum proteins as biomarkers of cattle resistance to bTB in Holstein-Friesian cows, 6-8-year-old, born and raised in similar conditions in herds with bTB prevalence >30%. Serum proteins obtained from uninfected cows (bTB-resistant; R) were compared to those from infected cows (bTB-susceptible; S), defined by a negative or positive bTB diagnosis, respectively. bTB diagnosis included: (i) single intradermal (caudal fold) tuberculin test, (ii) whole blood IFN-gamma test, (iii) gross visible lesions in lymph nodes and lungs by inspection at the abattoir, and (iv) a bacteriological culture for M. bovis. Using 2D-GE and LC-ESI-MS/MS, we found higher expression levels of primary amine oxidase (AO), complement component 5 (C5), and serotransferrin (TF) in R cattle than S cattle. In-house developed and standardized ELISAs for these novel biomarkers showed the best sensitivities of 72, 77, 77%, and specificities of 94, 94, 83%, for AO, C5, and TF, respectively. AUC-ROC (95% CI) values of 0.8935 (0.7906-0.9964), 0.9290 (0.8484-1.010), and 0.8580 (0.7291-0.9869) were obtained at cut-off points of 192.0, 176.5 ng/ml, and 2.1 mg/ml for AO, C5, and TF, respectively. These proteins are involved in inflammatory/immunomodulatory responses to infections and may provide a novel avenue of research to determine the mechanisms of protection against bTB. Overall, our results indicate that these proteins could be novel biomarkers to help identify cattle resistant to bTB, which in turn could be used to strengthen the effectiveness of existing eradication programs against bTB.

Cows as Bioreactors for the Production of Nutritionally and Biomedically Significant Proteins

Dairy and beef cattle make a vital contribution to global nutrition, and since their domestication, they have been continuously exposed to natural and artificial selection to improve production characteristics. The technologies of transgenesis and gene editing used in cattle are responsible for generating news characteristics in bovine breeding, such as alteration of nutritional components of milk and meat enhancing human health benefits, disease resistance decreasing production costs and offering safe products for human food, as well as the recombinant protein production of biomedical significance. Different methodologies have been used to generate transgenic cattle as bioreactors. These methods include the microinjection of vectors in pronuclear, oocyte or zygote, sperm-mediate transgenesis, and somatic cell nuclear transfer. Gene editing has been applied to eliminate unwanted genes related to human and animal health, such as allergy, infection, or disease, and to insert transgenes into specific sites in the host genome. Methodologies for the generation of genetically modified cattle are laborious and not very efficient. However, in the last 30 years, transgenic animals were produced using many biotechnological tools. The result of these modifications includes (1) the change of nutritional components, including proteins, amino acids and lipids for human nutrition; (2) the removal allergic proteins milk; (3) the production of cows resistant to disease; or (4) the production of essential proteins used in biomedicine (biomedical proteins) in milk and blood plasma. The genetic modification of cattle is a powerful tool for biotechnology. It allows for the generation of new or modified products and functionality that are not currently available in this species.

Interleukin 17D Enhances the Developmental Competence of Cloned Pig Embryos by Inhibiting Apoptosis and Promoting Embryonic Genome Activation

Simple Summary

The cloning technique is important for animal husbandry and biomedicine because it can be used to clone superior breeding livestock and produce multipurpose genetically modified animals. However, the success rate of cloning currently is very low due to the low developmental efficiency of cloned embryos, which limits the application of cloning. The low developmental competence is related to the excessive cell death in cloned embryos. Interleukin 17D (IL17D) is required for the normal development of mouse embryos by inhibiting cell death. This study aimed to investigate whether IL17D can improve cloned pig embryo development by inhibiting cell death. Addition of IL17D protein to culture medium decreased the cell death level and improved the developmental ability of cloned pig embryos. IL17D treatment enhanced cloned pig embryo development by regulating cell death-associated gene pathways and promoting genome-wide gene expression, which is probably via up-regulating the expression of a gene called GADD45B. This study provided a new approach to improve the pig cloning efficiency by adding IL17D protein to the culture medium of cloned pig embryos.

Abstract

Cloned animals generated by the somatic cell nuclear transfer (SCNT) approach are valuable for the farm animal industry and biomedical science. Nevertheless, the extremely low developmental efficiency of cloned embryos hinders the application of SCNT. Low developmental competence is related to the higher apoptosis level in cloned embryos than in fertilization-derived counterparts. Interleukin 17D (IL17D) expression is up-regulated during early mouse embryo development and is required for normal development of mouse embryos by inhibiting apoptosis. This study aimed to investigate whether IL17D plays roles in regulating pig SCNT embryo development. Supplementation of IL17D to culture medium improved the developmental competence and decreased the cell apoptosis level in cloned porcine embryos. The transcriptome data indicated that IL17D activated apoptosis-associated pathways and promoted global gene expression at embryonic genome activation (EGA) stage in treated pig SCNT embryos. Treating pig SCNT embryos with IL17D up-regulated expression of GADD45B, which is functional in inhibiting apoptosis and promoting EGA. Overexpression of GADD45B enhanced the developmental efficiency of cloned pig embryos. These results suggested that IL17D treatment enhanced the developmental ability of cloned pig embryos by suppressing apoptosis and promoting EGA, which was related to the up-regulation of GADD45B expression. This study demonstrated the roles of IL17D in early development of porcine SCNT embryos and provided a new approach to improve the developmental efficiency of cloned porcine embryos.

Steroid hormone modulates the production of cathelicidin and human β-defensins in lung epithelial cells and macrophages promoting Mycobacterium tuberculosis killing

Several studies have documented the interaction between the immune and endocrine systems as an effective defense strategy against tuberculosis, involving the production of several molecules and immunological processes. In this study, we determined the effect of cortisol and dehydroepiandrosterone (DHEA) on the production of antimicrobial peptides such as cathelicidin and human β-defensin (HBD) -2, and HBD-3 and their effect on intracellular growth of Mycobacterium tuberculosis (Mtb) in lung epithelial cells and macrophages. Our results showed that DHEA promotes the production of these antimicrobial peptides in infected cells, correlating with the decrease of Mtb bacilli loads. These results suggest the use of exogenous DHEA as an adjuvant for tuberculosis therapy.

Pigs Overexpressing Porcine β-Defensin 2 Display Increased Resilience to Glaesserella parasuis Infection

As the causative agent of Glässer’s disease, Glaesserella (Haemophilus) parasuis has led to serious economic losses to the swine industry worldwide. Due to the low cross-protection of vaccines and increasing antimicrobial resistance of G. parasuis, it is important to develop alternative approaches to prevent G. parasuis infection. Defensins are host defense peptides that have been suggested to be promising substitutes for antibiotics in animal production, while porcine β-defensin 2 (PBD-2) is a potent antimicrobial peptide discovered in pigs. Our previous study generated transgenic (TG) pigs overexpressing PBD-2, which displayed enhanced resistance to Actinobacillus pleuropneumoniae. In this study, the antibacterial activities of PBD-2 against G. parasuis are determined in vitro and in the TG pig model. The concentration-dependent bactericidal activity of synthetic PBD-2 against G. parasuis was measured by bacterial counting. Moreover, after being infected with G. parasuis via a cohabitation challenge model, TG pigs overexpressing PBD-2 displayed significantly milder clinical signs and less severe gross pathological changes than their wild-type (WT) littermates. The TG pigs also exhibited alleviated lung and brain lesions, while bacterial loads in the lung and brain tissues of the TG pigs were significantly lower than those of the WT pigs. Additionally, lung and brain homogenates from TG pigs possessed enhanced antibacterial activity against G. parasuis when compared with those from the WT pigs. Altogether, these proved that overexpression of PBD-2 could also endow pigs with increased resilience to G. parasuis infection, which further confirmed the potential of using the PBD-2 coding gene to develop disease-resistant pigs and provided a novel strategy to combat G. parasuis as well.

Immunoregulatory and Antimicrobial Activity of Bovine Neutrophil β-Defensin-5-Loaded PLGA Nanoparticles against Mycobacterium bovis

Mycobacterium bovis (M. bovis) is a member of the Mycobacterium tuberculosis complex imposing a high zoonotic threat to human health. The limited efficacy of BCG (Bacillus Calmette-Guérin) and upsurges of drug-resistant tuberculosis require new effective vaccination approaches and anti-TB drugs. Poly (lactic-co-glycolic acid) (PLGA) is a preferential drug delivery system candidate. In this study, we formulated PLGA nanoparticles (NPs) encapsulating the recombinant protein bovine neutrophil β-defensin-5 (B5), and investigated its role in immunomodulation and antimicrobial activity against M. bovis challenge. Using the classical water-oil-water solvent-evaporation method, B5-NPs were prepared, with encapsulation efficiency of 85.5% ± 2.5%. These spherical NPs were 206.6 ± 26.6 nm in diameter, with a negatively charged surface (ζ-potential -27.1 ± 1.5 mV). The encapsulated B5 protein from B5-NPs was released slowly under physiological conditions. B5 or B5-NPs efficiently enhanced the secretion of tumor necrosis factor α (TNF-α), interleukin (IL)-1β and IL-10 in J774A.1 macrophages. B5-NPs-immunized mice showed significant increases in the production of TNF-α and immunoglobulin A (IgA) in serum, and the proportion of CD4⁺ T cells in spleen compared with B5 alone. In immunoprotection studies, B5-NPs-immunized mice displayed significant reductions in pulmonary inflammatory area, bacterial burden in the lungs and spleen at 4-week after M. bovis challenge. In treatment studies, B5, but not B5-NPs, assisted rifampicin (RIF) with inhibition of bacterial replication in the lungs and spleen. Moreover, B5 alone also significantly reduced the bacterial load in the lungs and spleen. Altogether, our findings highlight the significance of the B5-PLGA NPs in terms of promoting the immune effect of BCG and the B5 in enhancing the therapeutic effect of RIF against M. bovis.

MicroRNA-31/184 is involved in transforming growth factor-β-induced apoptosis in A549 human alveolar adenocarcinoma cells

AIMS

TGF-β-induced alveolar epithelial cells apoptosis were involved in idiopathic pulmonary fibrosis (IPF). This study aimed to explore potential targets and mechanisms of IPF.

MAIN METHODS

mRNA and microRNA arrays were used to analyze differentially expressed genes and miRNAs. Several essential targets of TGF-β-SMADs and TGF-β-PI3K-AKT pathways were detected.

KEY FINDINGS

miR-31 and miR-184 expression levels were positively correlated with smad6 and smad2/akt expression levels in IPF patients. TGF-β could induce miR-31 and suppress miR-184 levels in A549 cells. miR-31 was confirmed to bind to the smad6-3'UTR and functionally suppress its expression. Down-regulated SMAD6 enhanced SMAD2/SMAD4 dimer formation and translocation due to its failure to prevent SMAD2 phosphorylation. In contrast, anti-fibrotic functions of miR-184 were abolished due to TGF-β directly suppressing miR-184 levels in A549 cells. When A549 was stimulated by TGF-β combined with or without miR-31 inhibitor/miR-184 mimic, it was showed that depleted miR-31 and/or increased miR-184 significantly ameliorated TGF-β-induced viability of A549 cells, as well as inhibited the expression of profibrotic factors, MMP7 and RUNX2.

SIGNIFICANCE

Inhibiting miR-31 and/or promoting miR-184 protect against TGF-β-induced fibrogenesis by respectively repressing the TGF-β-SMAD2 and TGF-β-PI3K-AKT signaling pathways, implying that miR-31/184 are potential targets and suggesting a new management strategy for IPF.

Evidence that changes in antimicrobial peptides during tuberculosis are related to disease severity, clinical presentation, specific therapy and levels of immune-endocrine mediators

Given the role of host defense peptides (HDPs) in the defensive response against mycobacteria, we analyzed the circulating levels of LL-37, β-defensin-2 and -3 in newly diagnosed patients with pulmonary (PTB) or pleural tuberculosis (PLTB) in whom measurements of pleural fluids were also performed. Severe PTB patients displayed higher circulating amounts of β-defensin-3, statistically different from controls, further decreasing upon antimycobacterial treatment. LL-37 concentrations appeared within the normal range at diagnosis, but tended to increase during treatment, becoming statistically upon its completion in moderate cases. PLTB patients revealed decreased levels of β-defensin-2 in presence of increased amounts of β-defensin-3 and LL-37; in their plasma or pleural fluids. Considering the immune-endocrine dysregulation of tuberculosis, we also performed correlation analysis detecting positive associations between levels of cortisol, IL-6 and β-defensin-3 in plasma from untreated severe patients as did their dehydroepiandrosterone and LL-37 values. Increased presence of β-defensins, may represent an attempt to improve defensive mechanisms; which also take part in the inflammatory reaction accompanying TB, reinforced by the association with immune-endocrine mediators. The divergent profile of PLTB patients, decreased β-defensin-2 but increased β-defensin-3 and LL-37 levels, suggests a differential role of these HDPs in a situation characterized for its better protective response.

Overexpressing ovotransferrin and avian β-defensin-3 improves antimicrobial capacity of chickens and poultry products

Zoonotic and foodborne diseases pose a significant burden, decreasing both human and animal health. Modifying chickens to overexpress antimicrobials has the potential to decrease bacterial growth on poultry products and boost chicken innate immunity. Chickens overexpressing either ovotransferrin or avian β-defensin-3 (AvβD3) were generated using Tol-2 transposons. Transgene expression at the RNA and protein level was seen in egg white, breast muscle, and serum. There were significant differences in the immune cell populations in the blood, bursa, and spleen associated with transgene expression including an increased proportion of CD8+ cells in the blood of ovotransferrin and AvβD3 transgenic birds. Expression of the antimicrobials inhibited the in vitro growth of human and chicken bacterial pathogens and spoilage bacteria. For example, transgene expression significantly reduced growth of aerobic and coliform bacteria in breast muscle and decreased the growth of Salmonella enterica in egg white. Overall these results indicate that overexpression of antimicrobials in the chicken can impact the immune system and increase the antimicrobial capacity of poultry products.

Efficient Generation of Transgenic Buffalos (Bubalus bubalis) by Nuclear Transfer of Fetal Fibroblasts Expressing Enhanced Green Fluorescent Protein

The possibility of producing transgenic cloned buffalos by nuclear transfer of fetal fibroblasts expressing enhanced green fluorescent protein (EGFP) was explored in this study. When buffalo fetal fibroblasts (BFFs) isolated from a male buffalo fetus were transfected with pEGFP-N1 (EGFP is driven by CMV and Neo is driven by SV-40) by means of electroporation, Lipofectamine-LTX and X-tremeGENE, the transfection efficiency of electroporation (35.5%) was higher than Lipofectamine-LTX (11.7%) and X-tremeGENE (25.4%, P < 0.05). When BFFs were transfected by means of electroporation, more embryos from BFFs transfected with pEGFP-IRES-Neo (EGFP and Neo are driven by promoter of human elongation factor) cleaved and developed to blastocysts (21.6%) compared to BFFs transfected with pEGFP-N1 (16.4%, P < 0.05). A total of 72 blastocysts were transferred into 36 recipients and six recipients became pregnant. In the end of gestation, the pregnant recipients delivered six healthy calves and one stillborn calf. These calves were confirmed to be derived from the transgenic cells by Southern blot and microsatellite analysis. These results indicate that electroporation is more efficient than lipofection in transfecting exogenous DNA into BFFs and transgenic buffalos can be produced effectively by nuclear transfer of BFFs transfected with pEGFP-IRES-Neo.

Expression of recombinant HBD3 protein that reduces Mycobacterial infection capacity

Bovine tuberculosis is a disease caused by Mycobacterium bovis (M. bovis) that leads to great economic losses in cattle production. The discovery of a reasonable bioagent to reduce M. bovis infection risk and environment contamination becomes significant and urgent. Previous study reported that human β-defensin-3 (HBD3) participated in Mycobacterial immunity and was recognized as a suitable candidate reagent. However, its minimal inhibitory concentration to M. bovis is not yet reported. In this study, we first purified HBD3 protein by recombinant-DNA technology and prokaryotic expression system. Subsequently, anti-bacterial tests were used to evaluate the basic bioactivity of the protein. Results revealed that recombinant HBD3 (rHBD3) protein inhibits Staphylococcus multiplication but not the host Escherichia coli. The growth curve of M. bovis showed that rHBD3 protein controls the proliferation of M. bovis in 20 μg/ml concentration. In addition, rHBD3 protein-incubated M. bovis exhibited reduced infectivity to alveolar epithelial cells and macrophages. In conclusion, the expression of rHBD3 protein is a potential ideal bio-regent for reducing M. bovis infection.

Divergent macrophage responses to Mycobacterium bovis among naturally exposed uninfected and infected cattle

Mycobacterium bovis, the causative agent of bovine tuberculosis (TB), is a successful pathogen that remains an important global threat to livestock. Cattle naturally exposed to M. bovis normally become reactive to the M. bovis-purified protein derivative (tuberculin) skin test; however, some individuals remain negative, suggesting that they may be resistant to infection. To better understand host innate resistance to infection, 26 cattle from herds with a long history of high TB prevalence were included in this study. We investigated the bactericidal activity, the production of reactive oxygen and nitrogen species and the TB-related gene expression profile after in vitro M. bovis challenge of monocyte-derived macrophages from cattle with TB (n=17) and from non-infected, exposed cattle (in-contacts, n=9). The disease status was established based on the tuberculin skin test and blood interferon-gamma test responses, the presence of visible lesions at inspection on abattoirs and the histopathology and culture of M. bovis. Although macrophages from TB-infected cattle enabled M. bovis replication, macrophages from healthy, exposed cattle had twofold lower bacterial loads, overproduced nitric oxide and had lower interleukin (IL)-10 gene expression (P⩽0.05). Higher mRNA expression levels of inducible nitric oxide synthase, C-C motif chemokine ligand 2 and IL-12 were observed in macrophages from all in-contact cattle than in macrophages from their TB-infected counterparts, which expressed more tumour necrosis factor-α; however, the differences were not statistically significant owing to individual variation. These results confirm that macrophage bactericidal responses have a crucial role in innate resistance to M. bovis infection in cattle.

Genome Editing in Large Animals

Genome editing in large animals has tremendous practical applications, from more accurate models for medical research through improved animal welfare and production efficiency. Although genetic modification in large animals has a 30 year history, until recently technical issues limited its utility. The original methods - pronuclear injection and integrating viruses - were plagued with problems associated with low efficiency, silencing, poor regulation of gene expression, and variability associated with random integration. With the advent of site specific nucleases such as TALEN and CRISPR/Cas9, precision editing became possible. When used on their own, these can be used to truncate or knockout genes through non-homologous end joining (NHEJ) with relatively high efficiency. When used with a template containing desired gene edits, these can be used to allow insertion of any desired changes to the genome through homologous recombination (HR) with substantially lower efficiency. Consideration must be given to the issues of marker sets and off-target effects. Somatic cell nuclear transfer is most commonly used to create animals from gene edited cells, but direct zygote injection and use of spermatogonial stem cells are alternatives under development. In developing gene editing projects, priority must be given to understanding the potential for off-target or unexpected effects of planned edits, which have been common in the past. Because of the increasing technical sophistication with which it can be accomplished, genome editing is poised to revolutionize large animal genetics, but attention must be paid to the underlying biology in order to maximize benefit.