Virus

A virus is a microscopic infectious agent that can reproduce only inside a host cell. Viruses infect all types of organisms: from animals and plants, to bacteria and archaea. Since the initial discovery of tobacco mosaic virus by Martinus Beijerinck in 1898, more than 5,000 types of virus have been described in detail, although most types of virus remain undiscovered. Viruses are ubiquitous, as they are found in almost every ecosystem on Earth, and are the most abundant type of biological entity on the planet. The study of viruses is known as virology, and is a branch of microbiology.

What is a Virus?

A virus is a small infectious agent that can only replicate inside the cells of another organism.

What is the Difference Between Bacteria and Viruses?

Virus History

Virus Origins

Virus Microbiology

Virus Classification

Virus Infection in Other Species

Human Diseases Caused by Viruses

Virus Uses in Virology

Virus Purification Methods

What are Filoviruses?

Antiviral Immunity and COVID-19

See more featured articles »

What is Vertical Transmission?

What is a Viral Mutation?

What are Viral Clades?

Are Viruses a Lifeform?

What Are Giant Viruses?

Virus Eradication, Extinction, and Elimination Explained

Latest Virus News and Research

Groundbreaking brain atlas sheds light on neural pathways for movement

Signals relayed to motor neurons from the brain enable muscle movement, but these signals typically pass through spinal interneurons before they reach their destination.

23 Dec 2024

New insights into respiratory syncytial virus and prevention strategies

Respiratory syncytial virus (RSV) is a major cause of respiratory infections, particularly in infants, children under 5 years, and older adults. Its rapid spread makes RSV a serious public health concern. Currently, there are no effective medications for RSV, and current treatment focuses on providing supportive care and preventing its spread.

20 Dec 2024

Rwanda successfully controls Marburg virus outbreak

An outbreak of Marburg Virus Disease (MVD) in Rwanda has officially been declared over by the Government of Rwanda, with no new cases recorded since the last patient tested negative on 7 November 2024, according to the World Health Organization (WHO).

20 Dec 2024

Shiitake-based supplement may help prevent liver damage progression

AHCC demonstrates potential in preventing liver fibrosis progression by inhibiting HSC activation and regulating key pathways involved in liver injury.

20 Dec 2024

Public health strategies essential for reducing airborne virus transmission

Half a decade on from the start of the COVID-19 pandemic, a study by the University of Surrey highlights the significant impact of combined public health measures in reducing airborne viral transmission.

20 Dec 2024

How America lost control of the bird flu, setting the stage for another pandemic

Keith Poulsen's jaw dropped when farmers showed him images on their cellphones at the World Dairy Expo in Wisconsin in October.

20 Dec 2024

Cellular RNA enhances MAVS signalosome activation in antiviral immunity

Scientists have uncovered a new role for a cell's own RNA in fending off attacks by RNA viruses. Some of the cell's RNA molecules, researchers found, help regulate antiviral signaling. These signals are part of the intricate coordination of immune responses against virus invasion.

19 Dec 2024

A scaffolded vaccine approach for broader influenza protection

Most people who get the seasonal influenza vaccine – which contains strains of viruses from distinct virus subtypes – mount a strong immune response to one strain, leaving them vulnerable to infection by the others, and researchers have long wondered what impacts such variable responses more – host genetics or prior exposure to virus strains.

19 Dec 2024

Pregnant women must be prioritized in pandemic vaccination programs

The vast majority of women who contract bird flu during pregnancy and their unborn baby will die from the virus, according to a new study. And the findings stress the importance of early inclusion of pregnant women in public health vaccination programs during pandemics.

19 Dec 2024

New design could make seasonal influenza vaccinations more broadly effective

Stanford Medicine scientists have designed a way to make our seasonal influenza vaccinations more broadly effective and possibly to protect us from new flu variants with pandemic potential.

19 Dec 2024

Breastfeeding after COVID-19 vaccination is safe, with minimal changes to milk composition

This study reveals how SARS-CoV-2 infection significantly alters human milk composition, while COVID-19 vaccination causes minimal, transient changes, underscoring the safety of breastfeeding during vaccination.

19 Dec 2024

Chronic gut infection may play role in Alzheimer’s disease progression

Arizona State University and Banner Alzheimer's Institute researchers, along with their collaborators, have discovered a surprising link between a chronic gut infection caused by a common virus and the development of Alzheimer's disease in a subset of people.

19 Dec 2024

Breakthrough in antigen recognition: TRACeR-I enhances immune targeting

Researchers describe TRACeR-I, a protein platform that can be used to engineer immune responses.

19 Dec 2024

Scientists detect rare H5N1 avian flu strain in Australian child after travel to India

A 2.5-year-old returning to Australia from India was infected with a reassortant H5N1 virus, revealing genetic mixing between avian influenza clades and gaps in South Asian surveillance.

18 Dec 2024

Modified lipid nanoparticles for targeted mRNA delivery to the brain

Penn Engineers have modified lipid nanoparticles (LNPs) -; the revolutionary technology behind the COVID-19 mRNA vaccines -; to not only cross the blood-brain barrier (BBB) but also to target specific types of cells, including neurons.

18 Dec 2024

Nutraceuticals: exploring potential benefits and challenges of an unregulated healthcare frontier

Nutraceuticals offer potential health benefits, from migraine relief to cognitive support, but safety and regulatory issues must be addressed for effective use.

18 Dec 2024

Researchers discover weakness in bacterial machinery that drives antibiotic resistance

Superbugs, bacteria that are immune to multiple antibiotics, pose a great challenge to modern medicine. Researchers from the B CUBE - Center for Molecular Bioengineering at TUD Dresden University of Technology and Institut Pasteur in Paris identified a weakness in the bacterial machinery that drives antibiotic resistance adaptation.

17 Dec 2024

Breakthrough in understanding influenza's protective coat opens path to new treatments

To fight the virus that causes influenza, one of the avenues being explored by scientists is the development of drugs capable of destabilizing its genome, made up of eight RNA molecules.

17 Dec 2024

Trump’s picks for top health jobs not just team of rivals but ‘team of opponents’

Many of President-elect Donald Trump's candidates for federal health agencies have promoted policies and goals that put them at odds with one another or with Trump's choice to run the Department of Health and Human Services, Robert F. Kennedy Jr., setting the stage for internal friction over public health initiatives.

17 Dec 2024