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Viruses

Viruses are nanoscale pathogens containing nucleic acids that can infect all life forms such as humans, animals, bacteria, and plants. Bacteria infecting viruses are called bacteriophages or phages. Since viruses do not have their own metabolism, they depend on a host cell for reproduction. For this reason, they are not counted as living organisms.

Each virus can exist in two different forms, either inside its host cell or as independent particles called virions. Virions consist of genetic material containing information about their blueprint, and a surrounding protein envelope called a capsid. Depending on the type of nucleic acid they are made of, viruses are classified as DNA or RNA, single-stranded or double-stranded. Some virions also possess a lipid bilayer membrane called an envelope. The origin of this envelope is a membrane of its host cell. For example, the HI virus (the causative agent of AIDS) or SARS-CoV-2 are enveloped viruses.

The morphology of virions varies greatly. Their size varies between 15 – 30 nm for small viruses like Circoviridae and 400 – 500 nm for the large giant viruses. Because of their size range, they can be perfectly measured by NTA. Their shape is determined by their protein coat and can be spherical, but also helical, spherical or isometrical.

The life cycle of viruses is independent of the origin of their host cell. The virion binds to a surface protein of a host cell and then introduces its nucleic acids into the cell. This can be done either by endocytosis or by injection. Then the host cell is forced to produce a high number of copies of the viral genome and its capsid proteins. The resulting newly synthesized virions leave the cell either by lysis of the host cell or are actively released by budding, which is typical for enveloped viruses. Some viruses integrate their genome into the host cells genome and are thereby replicated with every reproduction of the host cell. Normally, they stay silent until activated by an impulse, often thermal.

Viruses and diseases

Viruses are responsible for a high number of different diseases. In humans, some prominent examples are COVID-19, hepatitis, AIDS or Ebola.

Not every viral infection causes a disease. If the immune system is able to recognize and fight the pathogen due to vaccination or previous infection, a disease is avoided. However, because viruses lack an effective proof-reading strategy for their nucleic acid replication in the host cell, they have a high mutation rate. The resulting strains of a virus are often not recognized by the immune cells and can therefore cause a disease. This high mutation rate leads to a finely tuned adaptation to the host and can cause a jump to another species, such as from animals to humans, known as zoonosis. For example, the HI virus was first discovered in monkeys and most likely adapted to humans as hosts by eating infected meat.

The better the adaptation of the virus to its host, the lower the mortality, since the virus is dependent on its host. Therefore, coexistence of the virus with its host can be achieved, often with little or no symptoms. A typical example of a well-adapted virus is the herpes simplex virus, which has an infection rate of 65 – 90 % in adults worldwide and cannot be cleared by the immune system after a first infection. Herpes simplex infection shows mild symptoms from time to time when the immune system is weakened, but can cause severe symptoms in immunocompromised persons.

Viruses are also responsible for about 17% of all human cancer cases. The so-called oncoviruses responsible for this lead to uncontrolled cellular growth by altering intracellular signalling pathways, which causes cancer. A well-known example is the hepatitis B virus causing hepatocarcinoma or the human papillomavirus, which causes cervical cancer, for example.
Virologists are working to understand the host-virus-relationship and unravel the mechanisms of the immune response to a viral attack. Therefore, they need efficient methods to quantify the viral load, or titer required to cause an infection. One common method is the so-called plaque assay, in which different dilutions of virions are added to a monolayer of cultured cells. Due to the cytopathic effect of the viral infection, the cells become lysed, which is visible as colourless holes after a staining the cell monolayer. As a result, the number of plaque forming units (PFU) can be determined and is expressed as PFU/ml.

Plaque Assay

As an alternative test, the Median Tissue Culture Infectious Dose assay (TCID50) can be performed. In this assay, several varying concentrations of virions are added to a cell monolayer. After a defined time, the plates are examined for cytopathic effects of cell death. The concentration that results in 50% cytopathic effects is defined as TCID50 and is expressed as TCID50/ml.
You can read a comparison of both methods here.

Both methods lack the ability to quantify the total concentration of virions as they only indicate infections, but not particles. Therefore, the Nanoparticle Tracking Analysis technique is an important addition to the established methods. Virions can be quantified within a few minutes. An advantage of the Nanoparticle Tracking Analysis technique is that it can also measure the non-infectious fraction, which gives a more reliable result for the replication rate of a virus.

By using fluorescent Nanoparticle Tracking Analysis (F-NTA), defined virions can be stained and thus identified from complex samples such as patient material. Alternatively, F-NTA can be used to analyse the amount of successfully loaded (nucleic acid-containing) virions.

Since particle size can be measured with Nanoparticle Tracking Analysis, viral aggregation, which alters viral behaviour, can also be visualized.

Viruses as therapeutic approach

Viral Vector Vaccines

In addition to their pathogenic effect, viruses are also used for therapeutic purposes. For example, viruses can be used as vehicles for transporting genetic material into target cells. These viral vectors have been known to the public since the Corona pandemic, when viral vector vaccines directed against SARS-CoV-2 were invented. They transport the DNA or RNA of a pathogen into the target cell, where a protein is expressed which is then recognized by the immune system. Thereby the immune system is trained and able to prevent an infection by this pathogen afterwards.

Gene Therapy

Beyond their use as vaccines, viral vectors can also be used for gene therapy. This involves curing hereditary diseases by replacing the dysfunctional gene with a working one. However, since these approaches show undesirable side effects, their use has so far been limited to research and clinical trials.

Oncolytic Cancer Therapy

Viruses are known to cause cancer, but they can also cure cancer. These healing viruses are called oncolytic viruses and have diverse mechanisms to fight tumor cells. Some oncolytic viruses kill tumor cells directly by lysis. Others support the immune system to react against tumor cells, which results in suppressed tumour growth or even tumor shrinkage. Or they induce tumor suppressor genes in cancer cells, which reduces or stops tumor growth. This so-called oncolytic cancer therapy is the subject of numerous clinical studies.

Phage Therapy

The oldest medical use of viruses is phage therapy, in which bacteriophages are used to cure bacterial infections. It was invented as early as 1915 by Frederick Twort. After the invention of antibiotics, phage therapy became less interesting although it has some interesting advantages. It is very specific and therefore has fewer side effects compared to antibiotics. However, the interest in phage therapy is rising due to the increase in antibiotic resistance.

Nanoparticle Tracking Analysis is a common technique to ensure the quality of production of all these viral therapeutics.

Application Notes

Publications

Exosomal miR-17-3p Alleviates Programmed Necrosis in Cardiac Ischemia/Reperfusion Injury by Regulating TIMP3 Expression

Zhuyuan Liu, Didi Zhu, Fuchao Yu, Mingming Yang, Dan Huang, Zhenjun Ji, Wenbin Lu, and Genshan Ma

Oxidative Medicine and Cellular Longevity: Oxidative Stress and Programmed Cell Death in Cardiovascular Diseases

2022

ApplicationsCardiovascular DiseasesConcentration MeasurementExosomesExtracellular VesiclesSize MeasurementVesicles

miRNAmiaMyocardial ischemia/reperfusion injuryReperfusio

Full Text

Fetal Membranes Contribute to Drug Transport across the Feto-Maternal Interface Utilizing the Breast Cancer Resistance Protein (BCRP)

Ananthkumar Kammala, Meagan Benson, Esha Ganguly, Enkhtuya Radnaa, Talar Kechichian, Lauren Richardson and Ramkumar Menon

life: New Insights into the Placental and Placental Membrane Pathophysiology of Preterm Birth

2022

ApplicationsConcentration MeasurementExosomesExtracellular VesiclesSize MeasurementVesicles

breast cancer resistance proteindrug transportationpregnancy

Full Text

Synergy of Human Platelet-Derived Extracellular Vesicles with Secretome Proteins Promotes Regenerative Functions

Fausto Gueths Gomes, André Cronemberger Andrade, Martin Wolf, Sarah Hochmann, Linda Krisch, Nicole Maeding, Christof Regl, Rodolphe Poupardin, Patricia Ebner-Peking, Christian G. Huber, Nicole Meisner-Kober, Katharina Schallmoser and Dirk Strunk

Biomedicines

2022

Extracellular VesiclesSize MeasurementVesiclesZeta Potential

EV coronahuman platelet lysateproteomics

Full Text

Formation of a protein corona on the surface of extracellular vesicles in blood plasma

Eszter Á. Tóth, Lilla Turiák, Tamás Visnovitz, Csaba Cserép, Anett Mázló, Barbara W. Sódar, András I. Försönits, Gábor Petövári, Anna Sebestyén, Zsolt Komlósi, László Drahos, Ágnes Kittel, György Nagy, Attila Bácsi, Ádám Dénes, Yong Song Gho, Katalin É. Szabó-Taylor, Edit I. Buzás

Journal of Extracellular Vesicles

2021

ApplicationsConcentration MeasurementExtracellular VesiclesSize MeasurementVesicles

EV isolationEV purificationEV size distributionEVs in blood plasmaEVs in rheumatoid arthritisexternal plasma protein cargomedium sized EVsmEVsNTAplasma protein contaminationplasma protein-coated EVsprotein coronaTHP1 derived EVs

Full Text

P2RX7 inhibition reduces breast cancer induced osteolytic lesions – implications for bone metastasis

Karan M. Shah, Luke Tattersall, Aleana Hussain, Sarah C. Macfarlane, Alexander Williamson, Adelina E. Acosta-Martin, Janine T. Erler, Penelope D. Ottewell, Alison Gartland

bioRxiv

2021

ApplicationsBreast CancerCancerConcentration MeasurementExtracellular VesiclesMetastasisSize MeasurementVesicles

intra-tumoral hypoxiaP2RX7

Full Text

Salivary extracellular vesicles inhibit Zika virus but not SARS-CoV-2 infection

Carina Conzelmann, Rüdiger Groß, Min Zou, Franziska Krüger, André Görgens, Manuela O Gustafsson, Samir El Andaloussi, Jan Münch & Janis A. Müller

Journal of Extracellular Vesicles

2020

ApplicationsConcentration MeasurementExtracellular VesiclesSize MeasurementVesiclesViruses

Corona virusEV isolationEV purificationsaEVssalivary EVsSARS-CoV-2Zika virus

Full Text

Zeta Potential of Extracellular Vesicles: Toward Understanding the Attributes that Determine Colloidal Stability

Getnet Midekessa, Kasun Godakumara, James Ord, Janeli Viil, Freddy Lättekivi, Keerthie Dissanayake, Sergei Kopanchuk, Ago Rinken, Aneta Andronowska, Sourav Bhattacharjee, Toonika Rinken, and Alireza Fazeli

ACS Omega

2020

Extracellular VesiclesVesiclesZeta Potential

Buffer Influence on Zeta Potentialcolloidal stabilityJAr cell derived EVspH influence on zeta potentialsurface chargezeta potential

Full Text

Innate extracellular vesicles from melanoma patients suppress β-catenin in tumor cells by miRNA-34a

Jung-Hyun Lee, Jochen Dindorf, Martin Eberhardt, Xin Lai, Christian Ostalecki, Nina Koliha, Stefani Gross,Katja Blume, Heiko Bruns, Stefan Wild, Gerold Schuler, Julio Vera, Andreas S Baur

Life Science Alliance

2019

ApplicationsConcentration MeasurementExtracellular VesiclesSize MeasurementTechnical NanoparticlesVesicles

extracellular vesiclesmelanomamelanoma treatmentpEVsplasma-derived EVstumor development

Full Text

Optimisation of imaging flow cytometry for the analysis of single extracellular vesicles by using fluorescence-tagged vesicles as biological reference material

André Görgens, Michel Bremer, Rita Ferrer-Tur, Florian Murke, Tobias Tertel, Peter A. Horn, Sebastian Thalmann, Joshua A. Welsh, Christine Probst, Coralié Guerin, Chantal M. Boulanger, Jennifer C. Jones, Helmut Hanenberg, Uta Erdbrügger, Joanne Lannigan, Franz L. Ricklefs, Samir El-Andaloussi and Bernd Giebel

Journal of Extracellular Vesicles

2019

ApplicationsConcentration MeasurementExtracellular VesiclesSize MeasurementSmall Extracellular VesiclesTechnical NanoparticlesVesicles

Antibody LabellingCD63ev characterizationflow cytometrysEVssingle EV detectionsmall EV characterizationsmall EV identificationsmall EVssubpopulations

Full Text

Diet-resistant obesity is characterized by a distinct plasma proteomic signature and impaired muscle fiber metabolism

A B Thrush, G Antoun, M Nikpay, D A Patten, C DeVlugt, J-F Mauger, B L Beauchamp, P Lau, R Reshke, É Doucet, P Imbeault, R Boushel, D Gibbings, J Hager, A Valsesia, R S Slack, O Y Al-Dirbashi, R Dent, R McPherson & M-E Harper.

International Journal of Obesity

2018

ApplicationsConcentration MeasurementExosomesExtracellular VesiclesSize MeasurementVesicles

Diet resistanceexosomesfasting conditionshigh fat mealHSP72muscle metabolismobese diet-resistanceobesityoxidative stressplasma proteomicsROS

Full Text

Ebola Virus VP40 Modulates Cell Cycle and Biogenesis of Extracellular Vesicles

Michelle L Pleet, James Erickson, Catherine DeMarino, Robert A Barclay, Maria Cowen, Benjamin Lepene, Janie Liang, Jens H Kuhn, Laura Prugar, Spencer W Stonier, John M Dye, Weidong Zhou, Lance A Liotta, M Javad Aman, Fatah Kashanchi

The Journal of Infectuos Diseases

2018

ApplicationsConcentration MeasurementExtracellular VesiclesSize MeasurementTechnical NanoparticlesVesiclesViruses

Apoptosiscell cycleebola treatmentEbola virusEBOVEBOV pathogenesiEBOV treatmentEV biogenesisEVsextracellular vesiclesmonocyte apoptosispoptosis; cell cycleT cell apoptosisVP40

Full Text

TNFα and IL-1β modify the miRNA cargo of astrocyte shed extracellular vesicles to regulate neurotrophic signaling in neurons

Amrita Datta Chaudhuri, Raha M. Dastgheyb, Seung-Wan Yoo, Amanda Trout, C. Conover Talbot Jr, Haiping Hao, Kenneth W. Witwer & Norman J. Haughey.

Cell Death & Disease

2018

ApplicationsConcentration MeasurementExosomesExtracellular VesiclesSize MeasurementVesicles

Full Text

An In Vitro Potency Assay for Monitoring the Immunomodulatory Potential of Stromal Cell-Derived Extracellular Vesicles

Karin Pachler, Nina Ketterl, Alexandre Desgeorges, Zsuzsanna A. Dunai, Sandra Laner-Plamberger, Doris Streif, Dirk Strunk, Eva Rohde and Mario Gimona

International Journal of Molecular Sciences

2017

ApplicationsConcentration MeasurementExtracellular VesiclesSize MeasurementVesicles

exosomesextracellular vesiclesimmune modulationmesenchymalT-cell proliferation

Full Text

Atg5 Disassociates the V1V0-ATPase to Promote Exosome Production and Tumor Metastasis Independent of Canonical Macroautophagy

Huishan Guo, Maneka Chitiprolu, Luc Roncevic, Charlotte Javalet, Fiona J. Hemming, My Tran Trung, Lingrui Meng, Elyse Latreille, Christiano Tanese de Souza, Danielle McCulloch, R. Mitchell Baldwin, Rebecca Auer, Jocelyn Côté, Ryan Charles Russell, Rémy Sadoul, Derrick Gibbings

Developmental Cell

2017

ApplicationsCancerConcentration MeasurementExosomesExtracellular VesiclesSize MeasurementVesicles

AcidificationAtg5Autophagycancerendosomeexosomesextracellular vesiclesLC3multivesicular bodytumorV1V0-ATPase

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Gender-specific differential expression of exosomal miRNA in synovial fluid of patients with osteoarthritis

Kolhe R, Hunter M, Liu S, Jadeja RN, Pundkar C, Mondal AK, Mendhe B, Drewry M, Rojiani MV, Liu Y, Isales CM, Guldberg RE, Hamrick MW, Fulzele S

Scientific Reports - Nature

2017

ApplicationsConcentration MeasurementExtracellular VesiclesSize MeasurementVesicles

Full Text

Larger size extracellular vesicle as early biomarker in patients with metastatic pancreatic cancer

Dong Uk Kim, Francis A San Lucas, Matthew Cagley, Bret Stephens, Feven C Mulu, Jonathan Castillo, Vincent Bernard, Gauri R. Varadhachary, Matthew H. G. Katz, Hector A Alvarez, Anirban Maitra;

Journal of Clinical Oncology

2017

ApplicationsCancerConcentration MeasurementExtracellular VesiclesPancreatic CancerSize MeasurementVesicles

Bioactive MoleculesBiomarkerLiquid biopsymetastatispancreatic cancerPDACpredictorstumor progression

Full Text

Neutral Sphingomyelinase-2 Deficiency Ameliorates Alzheimer’s Disease Pathology and Improves Cognition in the 5XFAD Mouse

Michael B Dinkins, John Enasko, Caterina Hernandez, Guanghu Wang, Jina Kong, Inas Helwa, Yutao Liu, Alvin V Terry Jr, Erhard Bieberich

The Journal of neuroscience: the official Journal of the Society of Neuroscience

2017

ApplicationsExtracellular VesiclesSize MeasurementVesicles

Full Text

Publications related to research on viruses

Salivary extracellular vesicles inhibit Zika virus but not SARS-CoV-2 infection

Carina Conzelmann, Rüdiger Groß, Min Zou, Franziska Krüger, André Görgens, Manuela O Gustafsson, Samir El Andaloussi, Jan Münch & Janis A. Müller

Journal of Extracellular Vesicles

2020

ApplicationsConcentration MeasurementExtracellular VesiclesSize MeasurementVesiclesViruses

Corona virusEV isolationEV purificationsaEVssalivary EVsSARS-CoV-2Zika virus

Full Text

Ebola Virus VP40 Modulates Cell Cycle and Biogenesis of Extracellular Vesicles

Michelle L Pleet, James Erickson, Catherine DeMarino, Robert A Barclay, Maria Cowen, Benjamin Lepene, Janie Liang, Jens H Kuhn, Laura Prugar, Spencer W Stonier, John M Dye, Weidong Zhou, Lance A Liotta, M Javad Aman, Fatah Kashanchi

The Journal of Infectuos Diseases

2018

ApplicationsConcentration MeasurementExtracellular VesiclesSize MeasurementTechnical NanoparticlesVesiclesViruses

Apoptosiscell cycleebola treatmentEbola virusEBOVEBOV pathogenesiEBOV treatmentEV biogenesisEVsextracellular vesiclesmonocyte apoptosispoptosis; cell cycleT cell apoptosisVP40

Full Text

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