Indication of Neurodegenerative Cascade Initiation by Amyloid-like Aggregate-Forming EBV Proteins and Peptide in Alzheimer’s Disease

Abstract

The neurotropic potential of the Epstein-Barr virus (EBV) was demonstrated quite recently; however, the mechanistic details are yet to be explored. Therefore, the effects of EBV infection in the neural milieu remain underexplored. Previous reports have suggested the potential role of virus-derived peptides in seeding the amyloid-β aggregation cascade, which lies at the center of Alzheimer's disease (AD) pathophysiology. However, no such study has been undertaken to explore the role of EBV peptides in AD. In our research, ∼100 EBV proteins were analyzed for their aggregation proclivity in silico using bioinformatic tools, followed by the prediction of 20S proteasomal cleavage sites using online algorithms NetChop ver. 3.1 and Pcleavage, thereby mimicking the cellular proteasomal cleavage activity generating short antigenic peptides of viral origin. Our study reports a high aggregate-forming tendency of a 12-amino-acid-long ( 146 SYKHVFLSAFVY 157 ) peptide derived from EBV glycoprotein M (EBV-gM). The in vitro analysis of aggregate formation done using Congo red and Thioflavin-S assays demonstrated dose-and timedependent kinetics. Thereafter, Raman spectroscopy was used to validate the formation of secondary structures (α helix, β sheets) in the aggregates. Additionally, cytotoxicity assay revealed that even a low concentration of these aggregates has a lethal effect on neuroblastoma cells. The findings of this study provide insights into the mechanistic role of EBV in AD and open up new avenues to explore in the future.

Raman Spectroscopic Study of Amyloid Deposits in Gelatinous Drop-like Corneal Dystrophy

“…Limits of our study can be considered to be the evaluation of a single patient, even if the disease is rare, and the absence of a positive control for amyloid when Raman spectroscopy was considered. However, as mentioned above, the comparison with the existing literature [ 32 , 34 , 46 ] supported our data.…”

“…As to the band demonstrated at ~1440 cm −1 , particularly evident in both normal and dystrophic cornea, its molecular origin can be referred to the CH 2 peak, typical of either collagenous or non-collagenous organic molecules [ 46 ], such as lactoferrin [ 35 , 45 ].…”

“…The large band peaking at ~1650 cm −1 (Amide I band) can be related to the presence of collagen and proteins [ 46 , 47 ], whose content is increased in GDCD cornea [ 38 ].…”

Epstein-Barr Virus and Neurological Diseases

“…CD8 + T effector memory CD45RA + (T EMRA ) cells were associated with immune memory and negatively correlated with cognitive performance. In AD, adaptive immune responses are mediated by CD8 + T EMRA cells, and EBNA3A and BZLF1 interact with TEMR to release pro-inflammatory interferon-γ (IFNγ), TNF-α, and cytotoxic factors (NKG7, GZMA, and B2M), leading to decreased cognitive function and further exacerbation of AD ( Carbone et al, 2014 ; Gate et al, 2020 ; Kang and Liu, 2020 ; Tiwari et al, 2021 ). In addition, EBV-encoded BNLF-2a blocks the transporter associated with antigen processing (TAP).…”

“…In addition, EBV-encoded BNLF-2a blocks the transporter associated with antigen processing (TAP). BNLF-2a can further induce AD by inhibiting TAP and downregulating major human histocompatibility complex (MHC)-I and II expression, leading to the accumulation of neuronal cells and viral polypeptides in the environment ( Figure 1A ) ( Tiwari et al, 2021 ).…”