Abstract
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.
Highlights
An understanding of in vivo DNA transitions can be thwarted by obscurity of some transition products
We use DNA packaging of phage T3 as a model and extend our previous work on de-obscuring products of DNA packaging. We do this by introducing electron microscopy (EM) of thin sections (EM-TS) of T3 plaques
Present and (2) cannot be as quantitative as studies done in liquid culture, which is presumably a reason that in-plaque, EM-TS analysis of DNA packaging has not previously been reported
Summary
An understanding of in vivo DNA transitions can be thwarted by obscurity of some transition products. We use DNA packaging of phage T3 as a model and extend our previous work on de-obscuring products of DNA packaging. We do this by introducing electron microscopy (EM) of thin sections (EM-TS) of T3 plaques. Found necessary for packaging are a DNA packaging ATPase/endonuclease (gp for T3/T7; Figure 1; often called terminase) attached to a connector (gp for T3/T7; Figure 1; called portal) [1,2,3,4,5]. T3/T7 proteins are named by gp (gene product), followed by the number [6] of the protein’s gene
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