Incidence of Phage Capsid Organization on the Resistance to High Energy Proton Beams

Laura Maria De Plano,Alfio Torrisi,Vincenzo Zammuto,Anna Mackova,Letteria Silipigni,Mariapompea Cutroneo,Domenico Franco,Vladimir Havranek,Lorenzo Torrisi,Salvatore P P Guglielmino,Maria Giovanna Rizzo,Concetta Gugliandolo

doi:10.3390/app12030988

Abstract

The helical geometry of virus capsid allows simple self-assembly of identical protein subunits with a low request of free energy and a similar spiral path to virus nucleic acid. Consequently, small variations in protein subunits can affect the stability of the entire phage particle. Previously, we observed that rearrangement in the capsid structure of M13 engineered phages affected the resistance to UV-C exposure, while that to H2O2 was mainly ascribable to the amino acids’ sequence of the foreign peptide. Based on these findings, in this work, the resistance to accelerated proton beam exposure (5.0 MeV energy) of the same phage clones was determined at different absorbed doses and dose rates. Then, the number of viral particles able to infect and replicate in the natural host, Escherichia coli F+, was evaluated. By comparing the results with the M13 wild-type vector (pC89), we observed that 12III1 phage clones, with the foreign peptide containing amino acids favorable to carbonylation, exhibited the highest reduction in phage titer associated with a radiation damage (RD) of 35 × 10−3/Gy at 50 dose Gy. On the other hand, P9b phage clones, containing amino acids unfavorable to carbonylation, showed the lowest reduction with an RD of 4.83 × 10−3/Gy at 500 dose Gy. These findings could improve the understanding of the molecular mechanisms underlying the radiation resistance of viruses

Highlights

The last decades have been characterized by viral epidemics that led to the coronavirus pandemic in 2020 and 2021 [1,2]
The P9b phage clone was selected from a 9-mer phage library, and it displays the 9 amino acid sequence, QRKLAAKLT, which is fused to the major coat protein and is able to recognize Pseudomonas aeruginosa [33]
12III1 phage clone was obtained by screening of 12-mer phage library against anti-Caf1 monoclonal antibody and IgGs from AD-patients, in alternate biopanning cycles, named “double binding” selection. 12III1 display the 12 amino acid sequence, RWPPHFEWHFDD, able to detect IgG levels correlated with Alzheimer disease [34]

Summary

Introduction

The last decades have been characterized by viral epidemics that led to the coronavirus pandemic in 2020 and 2021 [1,2]. Molecular mechanisms, which can occur in natural mutations, determine both the emergence and the spread of new viral variants In this context, the increase in knowledge could help the protocols of disinfection or virus inactivation (for vaccine development), that are often slowed down due to the difficulties related to cultivation techniques and/or high contagiousness. Since a single alteration in the capsid proteins’ subunits affect the stability of the entire phage particle, the use of helical phages, engineered to express specific changes on known portions of their protein subunits, could help to identify the cause–effect relationships between specific mutations and new structural rearrangements in the capsid. The viability of pC89 (M13 wild-type vector) and two engineered phage clones, expressing 9 or 12 additional amino acids in the N-terminal end of pVIII capsid protein, was determined at different absorbed doses and dose rates

Bacteriophages

Phage Collection

Proton Irradiations

Findings

Conclusions