Virus diameter

Figure 2: Structures of viral capsids. The regularity of the structure of viruses has enabled detailed, atomic-level analysis of their construction patterns. This gallery shows a variety of the different geometries explored by the class of nearly spherical viruses.

HIV and influenza figures are 3D renderings of virions from the tomogram.. Symmetric virus structures adapted from T.

Baker et al. HIV structure adapted from J. Briggs et al. Harris, Proceedings of the National Academy of Sciences, , As a result of their enormous presence on the biological scene, viruses play a role not only in the health of their hosts, but in global geochemical cycles affecting the availability of nutrients across the planet.

This can strongly decrease the flow of biomass to higher trophic levels that feed on prokaryotes BNID Figure 3: The P30 protein dimer serves as a measure tape to help create the bacteriophage PRD1 capsid. Viruses are much smaller than the cells they infect. Indeed, it was their remarkable smallness that led to their discovery in the first place.

Researchers were puzzled by remnant infectious elements that could pass through filters small enough to remove pathogenic bacterial cells.

This led to the hypothesis of a new form of biological entity. These entities were subsequently identified as viruses. Viruses are among the most symmetric and beautiful of biological objects as shown in Figure 2. The figure shows that many viruses are characterized by an icosahedral shape with all of its characteristic symmetries i.

The outer protein shell, known as the capsid, is often relatively simple since it consists of many repeats of the same protein unit. The genomic material is contained within the capsid.

Transmission electron micrograph of the bacteriophage coliphage T4 ; courtesy of Dennis Kunkel's Microscopy. Exercise: Think-Pair-Share Questions We just learned that most viruses are much smaller than bacteria.

Compare the sizes of viruses and bacteria. Why are viruses able to be so much smaller than bacteria. Summary Viruses are usually much smaller than bacteria with the vast majority being submicroscopic, generally ranging in size from 5 to nanometers nm. Helical viruses consist of nucleic acid surrounded by a hollow protein cylinder or capsid and possessing a helical structure.

Polyhedral viruses consist of nucleic acid surrounded by a polyhedral many-sided shell or capsid, usually in the form of an icosahedron.

Zhu et al. Receptor binding affinity K d. Walls et al. Wrapp et al. Lan et al. Shang et al. The main disagreement between the studies seems to be on the k off. Membrane M; aa. Envelope E; 75 aa. Godet et al. Nucleoprotein aa. Genome length. Wu et al. Coronavirus genomes contain several 'accessory proteins' that are not essential for replication and are not always expressed.

As transcription start and protease cleavage sites are not trivial to identify bioinformatically, there is some uncertainty about the exact number of transcriptional units and proteins expressed by SARS-CoV Number of proteins. PLpro cleaves three sites at —, —, and — at the N-terminus and 3CLpro cuts at the other 11 sites at the C-terminus, and forming 15 non-structural proteins.

Evolution rate. Koyama et al. Mutation rate. Genome similarity. Reported values are percent nucleotide sequence identity. Schneider et al. Ng et al. Eclipse period. Burst size. Hirano et al. Shieh et al. Rockx et al. Type I and Type II pneumocyte and alveolar macrophage cell number. Values taken from table 4 in Crapo et al. Epithelial cells in mucous gland cell number and volume. We divide the mucous gland volume by the mucous cell volume to arrive at the total number of mucous cells in a mucous gland.

We multiply the surface density of mucous glands by the surface area of the nasal cavity to arrive at the total number of mucous glands, and then multiply the total number of mucous glands by the number of mucous cells per mucous gland. Type II pneumocyte volume. Fehrenbach et al. Alveolar macrophage volume. Crapo et al. Nasopharynx, throat, stool, and sputum. Seroconversion time time period until a specific antibody becomes detectable in the blood. Zhao et al.

To et al. Maintenance of antibody response to virus. Half-life on surfaces. Chin et al. Pastorino et al. More studies are urgently needed to clarify the implications of virion stability on the probability of infection from aerosols or surfaces. RNA stability on surfaces Moriarty et al. Basic reproductive number , R 0. Li et al. Park et al. Latent period from infection to being able to transmit.

He et al. As symptoms arise after five days see 'Incubation period' below , this implies a three-day latent period. Incubation period from infection to symptoms. Lauer et al. These estimates imply that, under conservative assumptions, out of every 10 cases 99th percentile, will develop symptoms after 14 days of active monitoring or quarantine".

Infectious period. Disease duration. WHO, : "Using available preliminary data, the median time from onset to clinical recovery for mild cases is approximately 2 weeks and is 3—6 weeks for patients with severe or critical disease". Time until diagnosis.

Xu et al. Case fatality rate. ECDC, - We use data from all countries with more than 50 death cases and calculate the uncorrected raw Case Fatality Rate for each country. Infection fatality rate. We rely on three independent approaches that estimate the IFR. The first relies on data about people who were extensively tested as a result of being repatriated. Verity et al. Ferguson et al. Nishiura et al. The second approach relies on data gathered from the Diamond Princess ship, where all passengers were tested.

Russell et al. The third approach relies on epidemiological modeling of case time-series from China. Mizumoto et al. The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication. Competing interests No competing interests declared. Author contributions Conceptualization, Resources, Data curation, Formal analysis, Validation, Investigation, Methodology, Writing - original draft, Writing - review and editing.

Resources, Data curation, Formal analysis, Validation, Investigation, Methodology, Writing - original draft, Writing - review and editing. Conceptualization, Resources, Data curation, Formal analysis, Supervision, Funding acquisition, Validation, Investigation, Methodology, Writing - original draft, Writing - review and editing.

Conceptualization, Resources, Data curation, Formal analysis, Supervision, Funding acquisition, Validation, Investigation, Methodology, Writing - original draft, Project administration, Writing - review and editing. This is a larger version of Figure 1.

In the interests of transparency, eLife publishes the most substantive revision requests and the accompanying author responses. This article summarizes a lot of knowledge on corona viruses into a digestible format. I would suggest not using the asterisk at all and putting which virus the knowledge derives from each time.

This language could be more precisely and consistently defined throughout. It probably makes sense for it to stay polyprotein as a polypeptide is any protein. Looking at the technical specifications will explain why N95 masks may work and may not be the best, but good enough. Experimentally determined PFE rating at 0. The Lancet — Perhaps this data is not yet firm enough yet.

The manuscript by Bar-On et al. Overall, the graphic is clear and the back-of-the-envelope calculations are useful and support or add to existing published data. The manuscript has been careful to include that many of the numbers are still being updated or are unknown at this time until more experiments are done, but this collation of sources and data will be a useful launchpad for researchers studying the virus as well as educators and a more general audience.

Due to the urgent dissemination of this information during the current crisis, I have only suggested just a few short edits that will add clarity for readers in the text.

As is, I think the manuscript is well supported by the citations listed, will be interesting and appropriate for the eLife readership and I support its publication. Currently this is an asterisk with small note in the blue panel, but since this applies to the entire large figure, please make this more obvious by making the text larger or drawing attention to it in some way.

It may be useful to include both the full name and commonly used name. You say that in a single mL of sputum implying one human sample that every possible base-pair mutation would be represented.

Even changing the language to not suggest a human sample would be better, unless there is a source suggesting this could be the case. We modified the figure to indicate textually which virus was used for each measurement.

We modified the figure to note the timescale as the eclipse period, and modified the definitions section to clarify the distinction between the eclipse period and the latent period. We added a definition for the following terms: Virion, Polyprotein, Nasopharynx, latent period, and interval of half-maximal infectiousness, as well as the names of the various virus strains.

We thank the reviewer for this highly relevant information. We added a reference for the prevalence of preexisting conditions in the section discussing the difference between the Case Fatality Rate and Infected Fatality Rate. After reviewing the literature, we believe further research is needed to solidify estimates on cytokine concentrations, and therefore have not included estimates regarding their concentration at this current version.

Indeed we do not expect the patient to be infected with many strains. We updated the text of the vignette and calculation to make it clearer. We updated the text as suggested.

The inference of the evolutionary rate is detailed in the reference cited. We have updated the text to make it more clear how we arrive at this number.

National Center for Biotechnology Information , U. Published online Apr 2. Author information Article notes Copyright and License information Disclaimer. Ron Milo: li.

Received Mar 27; Accepted Mar This article is distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use and redistribution provided that the original author and source are credited.

This article has been cited by other articles in PMC. Abstract The COVID pandemic is a harsh reminder of the fact that, whether in a single human host or a wave of infection across continents, viral dynamics is often a story about the numbers. Research organism: Human. Introduction The COVID pandemic has made brutally clear the need for further research into many aspects of viruses.

Open in a separate window. Figure 1. How long does it take a single infected person to yield one million infected people? What is the effect of physical distancing? Why was the initial quarantine period two weeks? What can we learn from the mutation rate of the virus? How stable and infectious is the virion on surfaces?

Definitions and measurement methods What are the meanings of R 0 , 'latent period' and 'infectious period'?