Tropism of Newcastle disease virus strains for chicken neurons, astrocytes, oligodendrocytes, and microglia.

BACKGROUND: Newcastle disease (ND), which is caused by infections of poultry species with virulent strains of Avian orthoavulavirus-1, also known as avian paramyxovirus 1 (APMV-1), and formerly known as Newcastle disease virus (NDV), may cause neurological signs and encephalitis. Neurological signs are often the only clinical signs observed in birds infected with neurotropic strains of NDV. Experimental infections have shown that the replication of virulent NDV (vNDV) strains is in the brain parenchyma and is possibly confined to neurons and ependymal cells. However, little information is available on the ability of vNDV strains to infect subset of glial cells (astrocytes, oligodendrocytes, and microglia). The objective of this study was to evaluate the ability of NDV strains of different levels of virulence to infect a subset of glial cells both in vitro and in vivo. Thus, neurons, astrocytes and oligodendrocytes from the brains of day-old White Leghorn chickens were harvested, cultured, and infected with both non-virulent (LaSota) and virulent, neurotropic (TxGB) NDV strains. To confirm these findings in vivo, the tropism of three vNDV strains with varying pathotypes (SA60 [viscerotropic], TxGB [neurotropic], and Tx450 [mesogenic]) was assessed in archived formalin-fixed material from day-old chicks inoculated intracerebrally. RESULTS: Double immunofluorescence for NDV nucleoprotein and cellular markers showed that both strains infected at least 20% of each of the cell types (neurons, astrocytes, and oligodendrocytes). At 24 h post-inoculation, TxGB replicated significantly more than LaSota. Double immunofluorescence (DIFA) with markers for neurons, astrocytes, microglia, and NDV nucleoprotein detected the three strains in all three cell types at similar levels. CONCLUSION: These data indicate that similar to other paramyxoviruses, neurons and glial cells (astrocytes, oligodendrocytes, and microglia) are susceptible to vNDV infection, and suggest that factors other than cellular tropism are likely the major determinant of the neurotropic phenotype.

Derivation of chicken induced pluripotent stem cells tolerant to Newcastle disease virus-induced lysis through multiple rounds of infection.

BACKGROUND: Newcastle disease (ND), caused by Newcastle disease virus (NDV), is a devastating disease of poultry and wild birds. ND is prevented by rigorous biocontainment and vaccination. One potential approach to prevent spread of the virus is production of birds that show innate resistance to NDV-caused disease. Induced pluripotent stem cell (iPSC) technology allows adult cells to be reprogrammed into an embryonic stem cell-like state capable of contributing to live offspring and passing on unique traits in a number of species. Recently, iPSC approaches have been successfully applied to avian cells. If chicken induced pluripotent stem cells (ciPSCs) are genetically or epigenetically modified to resist NDV infection, it may be possible to generate ND resistant poultry. There is limited information on the potential of ciPSCs to be infected by NDV, or the capacity of these cells to become resistant to infection. The aim of the present work was to assess the characteristics of the interaction between NDV and ciPSCs, and to develop a selection method that would increase tolerance of these cells to NDV-induced cellular damage. RESULTS: Results showed that ciPSCs were permissive to infection with NDV, and susceptible to virus-mediated cell death. Since ciPSCs that survived infection demonstrated the ability to recover quickly, we devised a system to select surviving cells through multiple infection rounds with NDV. ciPSCs that sustained 9 consecutive infections had a statistically significant increase in survival (up to 36 times) compared to never-infected ciPSCs upon NDV infection (tolerant cells). Increased survival was not caused by a loss of permissiveness to NDV replication. RNA sequencing followed by enrichment pathway analysis showed that numerous metabolic pathways where differentially regulated between tolerant and never-infected ciPSCs. CONCLUSIONS: Results demonstrate that ciPSCs are permissive to NDV infection and become increasingly tolerant to NDV under selective pressure, indicating that this system could be applied to study mechanisms of cellular tolerance to NDV.

Development, characterization and optimization of a new suspension chicken-induced pluripotent cell line for the production of Newcastle disease vaccine.

Traditionally, substrates for production of viral poultry vaccines have been embryonated eggs or adherent primary cell cultures. The difficulties and cost involved in scaling up these substrates in cases of increased demand have been a limitation for vaccine production. Here, we assess the ability of a newly developed chicken-induced pluripotent cell line, BA3, to support replication and growth of Newcastle disease virus (NDV) LaSota vaccine strain. The characteristics and growth profile of the cells were also investigated. BA3 cells could grow in suspension in different media to a high density of up to 7.0 × 10(6) cells/mL and showed rapid proliferation with doubling time of 21 h. Upon infection, a high virus titer of 1.02 × 10(8) EID50/mL was obtained at 24 h post infection using a multiplicity of infection (MOI) of 5. In addition, the cell line was shown to be free of endogenous and exogenous Avian Leukosis viruses, Reticuloendotheliosis virus, Fowl Adenovirus, Marek's disease virus, and several Mycoplasma species. In conclusion, BA3 cell line is potentially an excellent candidate for vaccine production due to its highly desirable industrially friendly characteristics of growing to high cell density and capability of growth in serum free medium.

Delayed Newcastle disease virus replication using RNA interference to target the nucleoprotein.

Each year millions of chickens die from Newcastle disease virus (NDV) worldwide leading to severe economic and food losses. Current vaccination campaigns have limitations especially in developing countries, due to elevated costs, need of trained personnel for effective vaccine administration, and functional cold chain network to maintain vaccine viability. These problems have led to heightened interest in producing new antiviral strategies, such as RNA interference (RNAi). RNAi methodology is capable of substantially decreasing viral replication at a cellular level, both in vitro and in vivo. In this study, we utilize microRNA (miRNA)-expressing constructs (a type of RNA interference) in an attempt to target and knockdown five NDV structural RNAs for nucleoprotein (NP), phosphoprotein (P), matrix (M), fusion (F), and large (L) protein genes. Immortalized chicken embryo fibroblast cells (DF-1) that transiently expressed miRNA targeting NP mRNA, showed increased resistance to NDV-induced cytopathic effects, as determined by cell count, relative to the same cells expressing miRNA against alternative NDV proteins. Upon infection with NDV, DF-1 cells constitutively expressing the NP miRNA construct had improved cell survival up to 48 h post infection (h.p.i) and decreased viral yield up to 24 h.p.i. These results suggest that overexpression of the NP miRNA in cells and perhaps live animal may provide resistance to NDV.

Controlled Cortical Impact Severity Results in Graded Cellular, Tissue, and Functional Responses in a Piglet Traumatic Brain Injury Model.

A number of pre-clinical rodent models have been developed in an effort to recapitulate injury mechanisms and identify potential therapeutics for traumatic brain injury (TBI), which is a major cause of death and long-term disability in the United States. The lack of restorative treatments for TBI, however, has led to considerable criticism of current pre-clinical therapeutic development strategies-namely, the translatability of widely used rodent models to human patients. The use of large animal models, such as the pig, with more brain anatomy and physiology comparable to humans may enhance the translational capacity of current pre-clinical animal models. The objective of this study was to develop and characterize a graded piglet TBI model with quantitative pathological features at the cellular, tissue, and functional level that become more prominent with increasing TBI severity. A graded TBI was produced by controlled cortical impact (CCI) in "toddler-aged" Landrace piglets by increasing impact velocity and/or depth of depression to 2 m/sec; 6 mm; 4 m/sec; 6 mm; 4 m/sec; 12 mm; or 4 m/sec; 15 mm, producing a range of neural injury responses that corresponded to injury severity. Quantitative gait analysis was performed pre-TBI and one, three, and seven days post-TBI, and piglets were sacrificed seven days post-TBI. Increasing impact parameters correlated to increases in lesion size with piglets that sustained a 6 mm depth of depression exhibiting significantly smaller lesions than piglets that sustained a depth of depression of 12 mm or 15 mm. Similarly, the extent of neuronal loss, astrogliosis/astrocytosis, and white matter damage became more prominent as CCI parameters were increased. These cellular and tissue-level changes correlated with motor function deficits including swing/stance time, stride velocity, and two- versus three-limb support. The piglet TBI model described here could serve as a translational platform for studying TBI sequelae across injury severities and identifying novel therapeutics.

Scaled traumatic brain injury results in unique metabolomic signatures between gray matter, white matter, and serum in a piglet model.

Traumatic brain injury (TBI) is a leading cause of death and long-term disability in the United States. The heterogeneity of the disease coupled with the lack of comprehensive, standardized scales to adequately characterize multiple types of TBI remain to be major challenges facing effective therapeutic development. A systems level approach to TBI diagnosis through the use of metabolomics could lead to a better understanding of cellular changes post-TBI and potential therapeutic targets. In the current study, we utilize a GC-MS untargeted metabolomics approach to demonstrate altered metabolism in response to TBI in a translational pig model, which possesses many neuroanatomical and pathophysiologic similarities to humans. TBI was produced by controlled cortical impact (CCI) in Landrace piglets with impact velocity and depth of depression set to 2m/s;6mm, 4m/s;6mm, 4m/s;12mm, or 4m/s;15mm resulting in graded neural injury. Serum samples were collected pre-TBI, 24 hours post-TBI, and 7 days post-TBI. Partial least squares discriminant analysis (PLS-DA) revealed that each impact parameter uniquely influenced the metabolomic profile after TBI, and gray and white matter responds differently to TBI on the biochemical level with evidence of white matter displaying greater metabolic change. Furthermore, pathway analysis revealed unique metabolic signatures that were dependent on injury severity and brain tissue type. Metabolomic signatures were also detected in serum samples which potentially captures both time after injury and injury severity. These findings provide a platform for the development of a more accurate TBI classification scale based unique metabolomic signatures.

Nonviral minicircle generation of induced pluripotent stem cells compatible with production of chimeric chickens.

Chickens are vitally important in numerous countries as a primary food source and a major component of economic development. Efforts have been made to produce transgenic birds through pluripotent stem cell [primordial germ cells and embryonic stem cells (ESCs)] approaches to create animals with improved traits, such as meat and egg production or even disease resistance. However, these cell types have significant limitations because they are hard to culture long term while maintaining developmental plasticity. Induced pluripotent stem cells (iPSCs) are a novel class of stem cells that have proven to be robust, leading to the successful development of transgenic mice, rats, quail, and pigs and may potentially overcome the limitations of previous pluripotent stem cell systems in chickens. In this study we generated chicken (c) iPSCs from fibroblast cells for the first time using a nonviral minicircle reprogramming approach. ciPSCs demonstrated stem cell morphology and expressed key stem cell markers, including alkaline phosphatase, POU5F1, SOX2, NANOG, and SSEA-1. These cells were capable of rapid growth and expressed high levels of telomerase. Late-passage ciPSCs transplanted into stage X embryos were successfully incorporated into tissues of all three germ layers, and the gonads demonstrated significant cellular plasticity. These cells provide an exciting new tool to create transgenic chickens with broad implications for agricultural and transgenic animal fields at large.

α-1,3-Galactosyltransferase knockout pig induced pluripotent stem cells: a cell source for the production of xenotransplant pigs.

The shortage of human organs and tissues for transplant has led to significant interest in xenotransplantation of pig tissues for human patients. However, transplantation of pig organs results in an acute immune rejection, leading to death of the organ within minutes. The α-1,3-galactosyltransferase (GALT) gene has been knocked out in pigs to reduce rejection, yet additional genes need to be modified to ultimately make pig tissue immunocompatible with humans. The development of pig induced pluripotent stem cells (piPSCs) from GALT knockout (GALT-KO) tissue would provide an excellent cell source for complex genetic manipulations (e.g., gene targeting) that often require highly robust and proliferative cells. In this report, we generated GALT-KO piPSCs by the overexpression of POU5F1, SOX2, NANOG, LIN28, KLF-4, and C-MYC reprogramming genes. piPSCs showed classical stem cell morphology and characteristics, expressing integrated reprogramming genes in addition to the pluripotent markers AP, SSEA1, and SSEA4. GALT-KO piPSCs were highly proliferative and possessed doubling times and telomerase activity similar to human embryonic stem cells. These results demonstrated successful reprogramming of GALT-KO fibroblasts into GALT-KO piPSCs. GALT-KO piPSCs are potentially an excellent immortal cell source for the generation of pigs with complex genetic modifications for xenotransplantation, somatic cell nuclear transfer, or chimera formation.