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Open AccessCommunication

Electron Microscopy of In-Plaque Phage T3 Assembly: Proposed Analogs of Neurodegenerative Disease Triggers

1
Department of Biochemistry and Structural Biology, The University of Texas Health Science Center, San Antonio, TX 78229–3900, USA
2
Department of Pathology, The University of Texas Health Science Center, San Antonio, TX 78229–3900, USA
*
Author to whom correspondence should be addressed.
Pharmaceuticals 2020, 13(1), 18; https://doi.org/10.3390/ph13010018
Received: 19 December 2019 / Revised: 9 January 2020 / Accepted: 15 January 2020 / Published: 18 January 2020
Increased knowledge of virus assembly-generated particles is needed for understanding both virus assembly and host responses to virus infection. Here, we use a phage T3 model and perform electron microscopy (EM) of thin sections (EM-TS) of gel-supported T3 plaques formed at 30 °C. After uranyl acetate/lead staining, we observe intracellular black particles, some with a difficult-to-see capsid. Some black particles (called LBPs) are larger than phage particles. The LBP frequency is increased by including proflavine, a DNA packaging inhibitor, in the growth medium and increasing plaque-forming temperature to 37 °C. Acidic phosphotungstate-precipitate (A-PTA) staining causes LBP substitution by black rings (BRs) that have the size and shape expected of hyper-expanded capsid containers for LBP DNA. BRs are less frequent in liquid cultures, suggesting that hyper-expanded capsids evolved primarily for in-gel (e.g., in-biofilm) propagation. BR-specific A-PTA staining and other observations are explained by α-sheet intense structure of the major subunit of hyper-expanded capsids. We hypothesize that herpes virus triggering of neurodegenerative disease occurs via in-gel propagation-promoted (1) generation of α-sheet intense viral capsids and, in response, (2) host production of α-sheet intense, capsid-interactive, innate immunity amyloid protein that becomes toxic. We propose developing viruses that are therapeutic via detoxifying interaction with this innate immunity protein. View Full-Text
Keywords: assembly-generated particles; obscure; phage capsids; protein staining; protein structure; thin sections assembly-generated particles; obscure; phage capsids; protein staining; protein structure; thin sections
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MDPI and ACS Style

Serwer, P.; Hunter, B.; Wright, E.T. Electron Microscopy of In-Plaque Phage T3 Assembly: Proposed Analogs of Neurodegenerative Disease Triggers. Pharmaceuticals 2020, 13, 18.

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