Expression patterns of prion protein gene in differential genotypes sheep: quantification using molecular beacon real-time RT-PCR

Splenic proteome profiling in response to Marek's disease virus strain GX0101 infection

Marek's disease virus (MDV) strain GX0101 was the first reported field strain of recombinant gallid herpesvirus type 2 (GaHV-2). However, the splenic proteome of MDV-infected chickens remains unclear. In this study, a total of 28 1-day-old SPF chickens were intraperitoneally injected with chicken embryo fibroblast (CEF) containing 2000 PFU GX0101. Additionally, a control group, consisting of four one-day-old SPF chickens, received intraperitoneal equal doses of CEF. Blood and various tissue samples were collected at different intervals (7, 14, 21, 30, 45, 60, and 90 days post-infection; dpi) for histopathological, real-time PCR, and label-free quantitative analyses. The results showed that the serum expressions of MDV-related genes, meq and gB, peaked at 45 dpi. The heart, liver, and spleen were dissected at 30 and 45 dpi, and their hematoxylin-eosin staining indicated that virus infection compromised the normal organizational structure at 45 dpi. Particularly, the spleen structure was severely damaged, and the lymphocytes in the white medulla were significantly reduced. Furthermore, liquid chromatography-mass spectrometry (LC-MS) and label-free techniques were used to analyze the difference in splenic proteome profiles of the experimental and control groups at 30 and 45 dpi. Proteomic analysis identified 1660 and 1244 differentially expressed proteins (DEPs) at 30 and 40 dpi, respectively, compared with the uninfected spleen tissues. According to GO analysis, these DEPs were involved in processes such as organelle organization, cellular component biogenesis, cellular component assembly, anion binding, small molecule binding, metal ion binding, cation binding, cytosol, nuclear part, etc. Additionally, KEGG analysis indicated that the following pathways were linked to MDV-induced inflammation, apoptosis, and tumor: Wnt, Hippo, AMPK, cAMP, Notch, TGF-β, PI3K-Akt, Rap1, Ras, Calcium, NF-κB, PPAR, cGMP-PKG, Apoptosis, VEGF, mTOR, FoxO, TNF, JAK-STAT, MAPK, Prion disease, T cell receptor, and B cell receptor. We finally screened 674 DEPs that were linked to MDV infection in spleen tissue. This study improves our understanding of the MDV response mechanism in the spleen.

Effect of Two Different Drug-Resistant Staphylococcus aureus Strains on the Physiological Properties of MAC-T Cells and Their Transcriptome Analysis

Staphylococcus aureus (S. aureus) is one of the main pathogens causing mastitis in dairy cows. The current work mainly focuses on the pathway of apoptosis induction in MAC-T cells caused by S. aureus infection or other factors. However, the physiological characteristics of S. aureus infected MAC-T cells and the resulting mRNA expression profile remain unknown particularly in the case of diverse drug resistant strains. Methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) strains were used to infect MAC-T cells to investigate this issue. The adhesion, invasion and apoptosis ability of MRSA-infected group and MSSA-infected group was assessed over time (2, 4, 6, 8, and 12 h). After 8 h, the RNA sequencing was conducted on the MRSA-infected and the MSSA-infected with uninfected MAC-T cells as controls. The results showed that the adhesion and invasion ability of MRSA-infected and MSSA-infected to MAC-T cells increased and then decreased with infection time, peaking at 8 h. The adhesion and invasion rates of the MSSA-infected were substantially lower than those of the MRSA-infected, and the invasion rate of the MSSA-infected group was nearly non-existent. Then the apoptosis rate of MAC-T cells increased as the infection time increased. The transcriptome analysis revealed 549 differentially expressed mRNAs and 390 differentially expressed mRNAs in MRSA-infected and MSSA-infected MAC-T cells, respectively, compared to the uninfected MAC-T cells. According to GO analysis, these differentially expressed genes were involved in immune response, inflammation, apoptosis, and other processes. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated the following pathways were linked to adhesion, invasion inflammation and apoptosis, including AMPK, FOXO, HIF-1, IL-17, JAK-STAT, MAPK, mTOR, NF-κB, p53, PI3K-Akt, TNF, Toll-like receptor, Rap1, RAS, prion disease, the bacterial invasion of epithelial cells pathway. We found 86 DEGs from 41 KEGG-enriched pathways associated with adhesion, invasion, apoptosis, and inflammation, all of which were implicated in MAC-T cells resistance to MRSA and MSSA infection. This study offers helpful data toward understanding the effect of different drug-resistant S. aureus on dairy cow mammary epithelial cells and aid in the prevention of mastitis in the dairy industry.

Pathogenesis, detection, and control of scrapie in sheep

In sheep, scrapie is a fatal neurologic disease that is caused by a misfolded protein called a prion (designated PrP^Sc). The normal cellular prion protein (PrP^C) is encoded by an endogenous gene, PRNP, that is present in high concentrations within the CNS. Although a broad range of functions has been described for PrP^C, its entire range of functions has yet to be fully elucidated. Accumulation of PrP^Sc results in neurodegeneration. The PRNP gene has several naturally occurring polymorphisms, and there is a strong correlation between scrapie susceptibility and PRNP genotype. The cornerstone of scrapie eradication programs is the selection of scrapie-resistant genotypes to eliminate classical scrapie. Transmission of classical scrapie in sheep occurs during the prenatal and periparturient periods when lambs are highly susceptible. Initially, the scrapie agent is disseminated throughout the lymphoid system and into the CNS. Shedding of the scrapie agent occurs before the onset of clinical signs. In contrast to classical scrapie, atypical scrapie is believed to be a spontaneous disease that occurs in isolated instances in older animals within a flock. The agent that causes atypical scrapie is not considered to be naturally transmissible. Transmission of the scrapie agent to species other than sheep, including deer, has been experimentally demonstrated as has the transmission of nonscrapie prion agents to sheep. The purpose of this review is to outline the current methods for diagnosing scrapie in sheep and the techniques used for studying the pathogenesis and host range of the scrapie agent. Also discussed is the US scrapie eradication program including recent updates.

Determining the Relative Susceptibility of Four Prion Protein Genotypes to Atypical Scrapie

Atypical scrapie is a sheep prion (PrP^Sc) disease whose epidemiology is consistent with a sporadic origin and is associated with specific polymorphisms of the normal cellular prion protein (PrP^C). To determine the relative amounts of PrP polymorphisms present in atypical scrapie, total PrP was digested with chymotrypsin to generate characteristic peptides spanning relevant polymorphisms at positions 136, 141, 154, 171, and 172 of sheep PrP^C. A multiple reaction monitoring method (MRM), employing ¹⁵N-labeled internal standards, was used to detect and quantify these polymorphisms present in both the PrP^Sc and PrP^C from heterozygous (ALRRY and ALHQY or ALRQD or AFRQY) atypical scrapie-infected or uninfected control sheep. Both polymorphisms of the full length and truncated (C1) natively expressed PrP^C are produced in equal amounts. The overall amount of PrP^C present in the infected or uninfected animals was similar. PrP^Sc isolated from heterozygotes was composed of significant amounts of both PrP polymorphisms, including the ALRRY polymorphism which is highly resistant to classical scrapie. Thus, an atypical scrapie infection does not result from an overexpression of sheep PrP^C. The replication of all atypical scrapie prions occurs at comparable rates, despite polymorphisms at positions 141, 154, 171, or 172.

Molecular beacons: a novel optical diagnostic tool

As a result of the efforts of the Human Genome Project and the rise in demand for molecular diagnostic assays, the development and optimization of novel hybridization probes have focused on speed, reliability, and accuracy in the identification of nucleic acids. Molecular beacons (MBs) are single-stranded, fluorophore-labeled nucleic acid probes that are capable of generating a fluorescent signal in the presence of target, but are dark in the absence of target. Because of the high specificity and sensitivity characteristics, MBs have been used in variety of fields. In this review, MBs are introduced and discussed as diagnostic tools in four sections: several technologies of MBs will be illustrated primarily; the limitation of MBs next; the third part is new fashions of MBs; and the last one is to present the application of MBs in disease diagnosis.