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 Uses in Virology

What are Filoviruses?

Virus Microbiology

What is the Difference Between Bacteria and Viruses?

Virus Purification Methods

Virus History

Virus Eradication, Extinction, and Elimination Explained

Virus Origins

Virus Infection in Other Species

Virus Classification

What Are Giant Viruses?

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Antiviral Immunity and COVID-19

What is Vertical Transmission?

Human Diseases Caused by Viruses

What are Viral Clades?

Are Viruses a Lifeform?

What is a Viral Mutation?

Jamestown Canyon Virus: An Emerging Arboviral Threat in Temperate Climates

Latest Virus News and Research

Unexpected behavior observed during interactions between immune cells and dying cells

Over the years, cell biology has built a detailed picture of how cells compartmentalize their internal functions. Central to this organization is the nucleus, which houses the genetic material and is separated from the cytoplasm by a robust nuclear envelope.

25 Feb 2026

Lingering brain inflammation found after mild COVID infection

Even a mild case of COVID-19 or the flu can impact the body long after the fever and cough fade, according to new Tulane University research that may help explain why some people struggle to feel fully recovered weeks or months later.

25 Feb 2026

Researchers uncover vulnerabilities in elusive HIV reservoir clones

A new study has overcome a long-standing challenge-how to isolate and study elusive HIV-infected cells called authentic reservoir clones (ARCs) that evade the immune system, making the disease difficult to cure.

24 Feb 2026

Viral RNA modifications trigger celiac inflammation

An EHU study indicates that a drug already approved for use in humans could help to reduce the inflammation associated with celiac disease.

24 Feb 2026

Hospitals fighting measles confront a challenge: Few doctors have seen it before

At around 2 a.m., 7-year-old twin brothers arrived at Mission Hospital in Asheville. Both had a fever, a cough, a rash, pink eye, and cold symptoms.

24 Feb 2026

Review: Natural selection can occur on multiple levels of biological organization

The common view of natural selection is based solely on the individual: A trait allows an organism to out-compete its rivals and is thus passed down to its offspring.

20 Feb 2026

Genome sequencing data reveals new insights into Epstein-Barr virus immunity

The Epstein-Barr virus (EBV) can cause certain types of cancer or autoimmune diseases, but how the body controls this common viral infection is largely unknown.

19 Feb 2026

Prenatal infection increases risk of alcohol misuse in adulthood

Exposure to infection and other immune stress in the womb increases the likelihood of alcohol misuse in adulthood, a risk that may be reduced through prenatal antioxidant treatment, a new Washington State University study shows.

19 Feb 2026

Study reveals previously unknown role for viral protein integrase in HIV's life cycle

The tiny shell protecting the HIV virus resembles a slightly rounded ice cream cone, but there is nothing sweet about it.

18 Feb 2026

Study reveals poxvirus's unique DNA clamp for gene activation

A research team at the University of Würzburg has deciphered another aspect of poxviral gene activation.

18 Feb 2026

Fred Hutch scientists reach crucial milestone in blocking Epstein Barr virus

Fred Hutch Cancer Center scientists reached a crucial milestone in blocking Epstein Barr virus (EBV), a pathogen estimated to infect 95% of the global population that is linked to multiple types of cancer, neurodegenerative diseases and other chronic health conditions.

17 Feb 2026

Nuclear speckles may be the unseen architects of viral infection spread

Recent research reveals that nuclear speckles play a key role in modifying viral messenger RNAs and in their transport out of the nucleus; therefore, nuclear speckles are an important subject of study in understanding viral infections.

17 Feb 2026

Innate immune priming may evolve into a broadly applicable infection-prevention strategy

Secondary infections caused by bacteria or viruses during hospital care remain a long-standing global challenge, despite advances in modern medicine.

16 Feb 2026

Obesity sharply increases hospitalisation risk from infections, global analysis shows

Adult obesity is associated with a substantially higher risk of severe hospital-treated or fatal infections across multiple pathogens, with risk increasing as obesity severity rises. Global modelling suggests roughly one in ten infection-related deaths worldwide may be attributable to adult obesity, although causality cannot be confirmed.

15 Feb 2026

Nasal COVID vaccine boost increases IgA responses linked to variant neutralisation

Intranasal boosting after prior intramuscular COVID vaccination induced strong mucosal IgA responses in a small human cohort. These antibodies showed markedly enhanced neutralising activity against Omicron variants and evidence of immune memory reprogramming toward mucosal protection.

15 Feb 2026

Protrusion-derived extracellular vesicles boost functional cargo transfer

Extracellular vesicles (EVs) are tiny membrane-bound particles released by cells to transport proteins and other molecules to neighboring cells. Because of this natural delivery ability, EVs have attracted growing interest as potential vehicles for therapeutic protein and genome-editing enzyme delivery.

13 Feb 2026

Engineered Listeria boosts innate immunity against cancer

After nearly 40 years of research on how Listeria bacteria manipulate our cells and battle our immune system to cause listeriosis, Daniel Portnoy and his colleagues have discovered a way to turn the bacteria into a potent booster of the immune system - and a potential weapon against cancer.

13 Feb 2026

Novel antibody 007 targets the elusive HIV envelope epitope

HIV-1 can be neutralized by antibodies which bind to vulnerable structures on the virus surface. One such vulnerable site is the so-called V3 glycan site of the viral envelope protein.

13 Feb 2026

Immunocompromised individuals require multiple Covid booster doses

Vaccinations alone may not be enough to protect people with compromised immune systems from infection, even if the vaccine has generated the production of antibodies, new research from the University of Cambridge has shown.

13 Feb 2026

RFK Jr. made promises in order to become health secretary. He’s broken many of them.

One year after taking charge of the nation’s health department, Health and Human Services Secretary Robert F. Kennedy Jr. hasn’t held true to many of the promises he made while appealing to U.S. senators concerned about the longtime anti-vaccine activist’s plans for the nation’s care.

13 Feb 2026