Dynamic Changes in Viral Loads during Co-Infection with a Recombinant Turkey Herpesvirus Vector Vaccine and Very Virulent Marek's Disease Virus In Vivo.

Marek's disease (MD), caused by the Marek's disease virus (MDV), is a common infectious tumor disease in chickens and was the first neoplastic disease preventable by vaccination. However, the vaccine cannot completely prevent virulent MDV infections, allowing both the vaccine and virulent MDV to coexist in the same chicken for extended periods. This study aims to investigate the changes in viral load of the very virulent strain Md5 and the rHVT-IBD vaccine in different chicken tissues using a real-time PCR assay. The results showed that the rHVT-IBD vaccine significantly reduced the viral load of MDV-Md5 in different organs, while the load of rHVT-IBD was significantly increased when co-infected with Md5. Additionally, co-infection with Md5 and rHVT-IBD in chickens not only changed the original viral load of both viruses but also affected the positive rate of Md5 at 14 days post-vaccination. The positive rate decreased from 100% to 14.29% (feather tips), 0% (skin), 33.33% (liver), 16.67% (spleen), 28.57% (thymus), 33.33% (bursa), and 66.67% (PBL), respectively. This study enhances our understanding of the interactions between HVT vector vaccines and very virulent MDV in chickens and provides valuable insights for the future development of MD vaccines.

Zinc enhances liquid-liquid phase separation of Tau protein and aggravates mitochondrial damages in cells.

Intraneuronal neurofibrillary tangles composed of Tau aggregates have been widely accepted as an important pathological hallmark of Alzheimer's disease. Liquid-liquid phase separation (LLPS) of Tau can lead to its aggregation, and Tau aggregation can then be enhanced by zinc. However, it is unclear whether zinc modulates the formation of Tau stress granules in cells. We herein report that zinc promotes the formation of stress granules containing a pathological mutant ΔK280 of full-length human Tau. Furthermore, zinc promotes LLPS of ΔK280 of full-length Tau, shifting the equilibrium phase boundary to a lower protein concentration, and modulates the liquid nature of droplets formed by this pathological mutation. Zinc also promotes pathological phosphorylation of ΔK280 in neuronal cells, and aggravates mitochondrial damage and elevates reactive oxygen species production induced by Tau aggregation. Importantly, we show that treatment of cells with zinc increases the interaction between full-length Tau and G3BP1 inside stress granules to promote the formation of Tau filaments and increase Tau toxicity in neuronal cells. Collectively, these results demonstrate how Tau condensation and mitochondrial damages induced by Tau aggregation are enhanced by zinc to deteriorate the pathogenesis of Alzheimer's disease, bridging the gap between Tau LLPS and aggregation in neuronal cells.

Genetic prion disease-related mutation E196K displays a novel amyloid fibril structure revealed by cryo-EM.

Prion diseases are caused by the conformational conversion of prion protein (PrP). Forty-two different mutations were identified in human PrP, leading to genetic prion diseases with distinct clinical syndromes. Here, we report the cryo­electron microscopy structure of an amyloid fibril formed by full-length human PrP with E196K mutation, a genetic Creutzfeldt-Jakob disease­related mutation. This mutation disrupts key interactions in the wild-type PrP fibril, forming an amyloid fibril with a conformation distinct from the wild-type PrP fibril and hamster brain­derived prion fibril. The E196K fibril consists of two protofibrils. Each subunit forms five ß strands stabilized by a disulfide bond and an unusual hydrophilic cavity stabilized by a salt bridge. Four pairs of amino acids from opposing subunits form four salt bridges to stabilize the zigzag interface of the two protofibrils. Our results provide structural evidences of the diverse prion strains and highlight the importance of familial mutations in inducing different strains.

Macromolecular crowding favors the fibrillization of ß2-microglobulin by accelerating the nucleation step and inhibiting fibril disassembly.

Hemodialysis-associated amyloidosis (HAA) involves the fibrillization of ß2-microglobulin (ß2M) and occurs in crowded physiological environments. However, how macromolecular crowding affects amyloid formation of ß2M remains elusive. Here we study the effects of macromolecular crowding on amyloid formation and fibril disassembly of wild-type human ß2M and its pathogenic mutant ΔN6. At strongly acidic pH2.5, the presence of a strong crowding agent (Ficoll 70 or dextran 70) not only dramatically accelerates the fibrillization of both wild-type ß2M and its ΔN6 variant by reducing the lag time to a large extent, indicating the acceleration of the nucleation phase, but also remarkably increases the amount of ß2M fibrils. At weakly acidic pH6.2, such an enhancing effect of macromolecular crowding on fibril formation is only observed for pathogenic mutant ΔN6, but not for wild-type ß2M which does not form amyloid fibrils in the absence and presence of a crowding agent. Thus, we propose that the monomers of ß2M form the nuclei, which is enhanced by macromolecular crowding, followed by the step of fibril elongation. Furthermore, at physiological pH, macromolecular crowding remarkably inhibits ß2M fibril disassembly by decreasing rate constants corresponding to fast and slow stages of fibril disaggregation. Our data demonstrate that macromolecular crowding favors the fibrillization of ß2M by accelerating the nucleation step and inhibiting fibril disassembly. Our findings provide clear evidence for the pathology of HAA that macromolecular crowding should be taken into account.