scholarly journals Epifluorescent microscopy to evaluate bacteriophage capsid integrity

BioTechniques ◽  
2007 ◽  
Vol 43 (4) ◽  
pp. 473-476 ◽  
Author(s):  
Kerusha Naicker ◽  
Steven I. Durbach
Keyword(s):  
Epifluorescent Microscopy ◽  
Capsid Integrity

scholarly journals Metastable Intermediates as Stepping Stones on the Maturation Pathways of Viral Capsids

mBio ◽  
2014 ◽  
Vol 5 (6) ◽  
Author(s):  
Giovanni Cardone ◽  
Robert L. Duda ◽  
Naiqian Cheng ◽  
Lili You ◽  
James F. Conway ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Large Scale ◽  
Structural Changes ◽  
Energy Landscape ◽  
Potential Hazard ◽  
Stepping Stones ◽  
Scanning Calorimetry ◽  
Conformational Effects ◽  
Capsid Maturation ◽  
Capsid Integrity

ABSTRACT As they mature, many capsids undergo massive conformational changes that transform their stability, reactivity, and capacity for DNA. In some cases, maturation proceeds via one or more intermediate states. These structures represent local minima in a rich energy landscape that combines contributions from subunit folding, association of subunits into capsomers, and intercapsomer interactions. We have used scanning calorimetry and cryo-electron microscopy to explore the range of capsid conformations accessible to bacteriophage HK97. To separate conformational effects from those associated with covalent cross-linking (a stabilization mechanism of HK97), a cross-link-incompetent mutant was used. The mature capsid Head I undergoes an endothermic phase transition at 60°C in which it shrinks by 7%, primarily through changes in its hexamer conformation. The transition is reversible, with a half-life of ~3 min; however, >50% of reverted capsids are severely distorted or ruptured. This observation implies that such damage is a potential hazard of large-scale structural changes such as those involved in maturation. Assuming that the risk is lower for smaller changes, this suggests a rationalization for the existence of metastable intermediates: that they serve as stepping stones that preserve capsid integrity as it switches between the radically different conformations of its precursor and mature states. IMPORTANCE Large-scale conformational changes are widespread in virus maturation and infection processes. These changes are accompanied by the release of conformational free energy as the virion (or fusogenic glycoprotein) switches from a precursor state to its mature state. Each state corresponds to a local minimum in an energy landscape. The conformational changes in capsid maturation are so radical that the question arises of how maturing capsids avoid being torn apart. Offering proof of principle, severe damage is inflicted when a bacteriophage HK97 capsid reverts from the (nonphysiological) state that it enters when heated past 60°C. We suggest that capsid proteins have been selected in part by the criterion of being able to avoid sustaining collateral damage as they mature. One way of achieving this—as with the HK97 capsid—involves breaking the overall transition down into several smaller steps in which the risk of damage is reduced.

scholarly journals Observation of Plasmids in Anucleate Cells of Escherichia coli with Epifluorescent Microscopy.

CYTOLOGIA ◽  
1993 ◽  
Vol 58 (1) ◽  
pp. 33-39
Author(s):  
K. Matsuuchi ◽  
K. Ohnishi ◽  
T. Iino ◽  
T. Kuroiwa
Keyword(s):  
Escherichia Coli ◽  
Epifluorescent Microscopy

scholarly journals Application of Capsid Integrity (RT-)qPCR to Assessing Occurrence of Intact Viruses in Surface Water and Tap Water in Japan

2021 ◽  
Vol 189 ◽  
pp. 116674
Author(s):  
Vu Duc Canh ◽  
Shotaro Torii ◽  
Hiroaki Furumai ◽  
Hiroyuki Katayama
Keyword(s):  
Surface Water ◽  
Tap Water ◽  
Capsid Integrity

scholarly journals Inactivation of Murine Norovirus on a Range of Copper Alloy Surfaces Is Accompanied by Loss of Capsid Integrity

2014 ◽  
Vol 81 (3) ◽  
pp. 1085-1091 ◽  
Author(s):  
Sarah L. Warnes ◽  
Emma N. Summersgill ◽  
C. William Keevil
Keyword(s):  
Stainless Steel ◽  
Viral Genome ◽  
Copper Alloy ◽  
Gastrointestinal Disease ◽  
Gene Copy ◽  
Viral Gene ◽  
Viral Gastroenteritis ◽  
Murine Norovirus ◽  
Ceramic Tiles ◽  
Capsid Integrity

ABSTRACTNorovirus is one of the most common causes of acute viral gastroenteritis. The virus is spread via the fecal-oral route, most commonly from infected food and water, but several outbreaks have originated from contamination of surfaces with infectious virus. In this study, a close surrogate of human norovirus causing gastrointestinal disease in mice, murine norovirus type 1 (MNV-1), retained infectivity for more than 2 weeks following contact with a range of surface materials, including Teflon (polytetrafluoroethylene [PTFE]), polyvinyl chloride (PVC), ceramic tiles, glass, silicone rubber, and stainless steel. Persistence was slightly prolonged on ceramic surfaces. A previous study in our laboratory observed that dry copper and copper alloy surfaces rapidly inactivated MNV-1 and destroyed the viral genome. In this new study, we have observed that a relatively small change in the percentage of copper, between 70 and 80% in copper nickels and 60 and 70% in brasses, had a significant influence on the ability of the alloy to inactivate norovirus. Nickel alone did not affect virus, but zinc did have some antiviral effect, which was synergistic with copper and resulted in an increased efficacy of brasses with lower percentages of copper. Electron microscopy of purified MNV-1 that had been exposed to copper and stainless steel surfaces suggested that a massive breakdown of the viral capsid had occurred on copper. In addition, MNV-1 that had been exposed to copper and treated with RNase demonstrated a reduction in viral gene copy number. This suggests that capsid integrity is compromised upon contact with copper, allowing copper ion access to the viral genome.

scholarly journals Rapid Membrane Filtration-Epifluorescent Microscopy Technique for Direct Enumeration of Bacteria in Raw Milk

1980 ◽  
Vol 39 (2) ◽  
pp. 423-429 ◽  
Author(s):  
Graham L. Pettipher ◽  
Roderick Mansell ◽  
Charles H. McKinnon ◽  
Christina M. Cousins
Keyword(s):  
Membrane Filtration ◽  
Raw Milk ◽  
Epifluorescent Microscopy ◽  
Microscopy Technique
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