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.

Virus Eradication, Extinction, and Elimination Explained

What Are Giant Viruses?

What are Filoviruses?

Virus Purification Methods

Human Diseases Caused by Viruses

Virus Classification

What are Viral Clades?

Virus Uses in Virology

Virus Origins

Virus Microbiology

Are Viruses a Lifeform?

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Latest Virus News and Research

New DNA-based vaccine scaffolds boost targeted immune responses to HIV

One of the biggest hurdles in developing an HIV vaccine is coaxing the body to produce the right kind of immune cells and antibodies. In most vaccines, HIV proteins are attached to a larger protein scaffolding that mimics a virus.

6 Feb 2026

Griffith researchers on the cusp of new vaccine to prevent chikungunya

Griffith University researchers are on the cusp of a new vaccine to prevent chikungunya, a global health threat which attacks human joint tissue.

6 Feb 2026

Enhanced natural killer cells show promise for HIV remission

More than 30 million people with HIV must take antiretroviral therapy (ART) medications daily to keep the virus under control, according to the Joint United Nations Programme on HIV/AIDS (UNAIDS).

5 Feb 2026

Weak governance hinders One Health outbreak response in Africa

Across Africa, One Health is endorsed at the top but often breaks down where outbreaks start, writes Albert Ansah.

5 Feb 2026

Study reveals evidence of silent mpox exposure in healthy Nigerians

New evidence suggests that mpox may be circulating quietly among healthy Nigerians, with some infections occurring without the symptoms that typically trigger detection by health authorities.

5 Feb 2026

Influenza D virus and canine coronavirus pose human risks

Two emerging pathogens with animal origins - influenza D virus and canine coronavirus - have so far been quietly flying under the radar, but researchers warn conditions are ripe for the viruses to spread more widely among humans.

5 Feb 2026

EBV-linked killer T cells implicated in multiple sclerosis

Researchers at UC San Francisco have uncovered a new clue to how Epstein-Barr virus (EBV) could contribute to multiple sclerosis (MS), a chronic autoimmune disease that affects nearly one million Americans.

5 Feb 2026

Breakthrough enables continuous laboratory growth of human norovirus

Researchers at Baylor College of Medicine report in Science Advances a breakthrough in human norovirus (HuNoV) research.

4 Feb 2026

Why did influenza fail to spread in a crowded indoor setting?

The EMIT-2 trial shows zero influenza transmission despite ideal conditions, suggesting a perfect storm is needed for the virus to spread effectively.

4 Feb 2026

Herpes virus infection softens cell nuclei through internal mechanical changes

A recent international research project has used advanced microscopy techniques and computational modeling to discover why virus infection changes the nuclear structures and biomechanical forces affecting the nucleus.

3 Feb 2026

A common diabetes drug may prevent long COVID when taken early

Research supports metformin's efficacy in reducing long COVID symptoms, suggesting its use in acute COVID-19 cases could alleviate long-term health impacts.

3 Feb 2026

Poll: Many adults over 50 skip flu and COVID vaccines

This winter's brutal flu season isn't over, and COVID-19 cases have risen recently too. But a new poll taken in recent weeks shows that vaccination against both viruses lags among people 50 and over, and the national survey reveals key reasons why.

3 Feb 2026

Single-dose HIV vaccine candidate induces neutralizing antibodies

Scientists at The Wistar Institute have developed an HIV vaccine candidate that achieves something never before observed in the field: inducing neutralizing antibodies against HIV after a single immunization in nonhuman primates.

3 Feb 2026

Six years after COVID-19: Lessons learned and pandemic preparedness

Six years ago, the Director-General of the World Health Organization sounded the highest global alarm available under international law at the time, declaring the outbreak of a new coronavirus disease (later known as COVID-19) a Public Health Emergency of International Concern (PHEIC).

3 Feb 2026