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.

Are Viruses a Lifeform?

Virus History

Virus Infection in Other Species

Human Diseases Caused by Viruses

What is Vertical Transmission?

Virus Uses in Virology

What is a Viral Mutation?

What Are Giant Viruses?

Jamestown Canyon Virus: An Emerging Arboviral Threat in Temperate Climates

Virus Origins

What are Viral Clades?

See more featured articles »

Antiviral Immunity and COVID-19

Virus Eradication, Extinction, and Elimination Explained

Virus Microbiology

What are Filoviruses?

Virus Purification Methods

Virus Classification

What is the Difference Between Bacteria and Viruses?

Latest Virus News and Research

Children develop stronger immunity after repeated infections in nursery

Young children who attend nursery get sick more often than those who don't, but they will go on to have fewer illnesses during early school years, finds a new review of evidence by a group of parent-scientists involving University College London (UCL) researchers.

18 Mar 2026

Protein targeted by cancer drugs may help the body fight influenza

A protein already targeted by FDA-approved cancer drugs may also help the body fight influenza, according to new research from The Jackson Laboratory (JAX).

18 Mar 2026

Modified lipid nanoparticles boost mRNA vaccines while reducing side effects

The most common side effects of mRNA vaccines like the COVID-19 shot are well known: soreness, mild fever and general malaise.

17 Mar 2026

Shingles vaccine linked to lower risk of serious cardiac events

People with heart disease who received a shingles vaccine had nearly half the rate of serious cardiac events a year later compared with those who did not get the vaccine, according to a study being presented at the American College of Cardiology's Annual Scientific Session (ACC.26).

17 Mar 2026

Swedish study reveals COVID-19 may increase glandular fever risk

Even individuals who did not become seriously ill with COVID-19 may have developed a weakened immune system that could lead to serious illnesses in the future.

17 Mar 2026

Precision mapping identifies household hotspots of schistosomiasis

High-precision mapping tools can pinpoint where schistosomiasis persists down to the household level, potentially transforming efforts to eliminate the disease affecting 250 million people, a 13-year study has found.

16 Mar 2026

Circular RNA produced by HIV boosts viral replication

For decades scientists have recognized that human immunodeficiency virus (HIV) is a formidable viral pathogen.

13 Mar 2026

Targeting two influenza proteins may reduce viral transmission

A long-running debate in vaccine design revolves around whether a vaccine should be optimized to prevent the virus from replicating inside an infected host or prevent the virus from transmitting to others.

13 Mar 2026

New method creates longer lasting CAR T cells for cancer therapy

A research team led by Albert Einstein College of Medicine scientists has developed a new strategy to engineer immune cells that dramatically prolongs their effectiveness after being infused into patients to fight cancer and HIV, addressing a major limitation of current treatments.

13 Mar 2026

Doctors warn of a deadly complication from measles outbreaks

The first sign came when Deepanwita Dasgupta was 5 and started stumbling more while playing at her home in Bangalore in southern India.

13 Mar 2026

How the aging gastrointestinal tract drives age-related cognitive decline

We become forgetful as we age. This is often seen as a universal truth, but in fact it is far from universal: some people remain incredibly sharp at 100 years old, while others experience memory loss starting in middle age.

11 Mar 2026

Prior flu exposure may weaken the immune response to other strains

Prior exposure to one strain of influenza virus may weaken children's ability to mount an effective antibody response against their subsequent exposure to a different flu strain, according to a study led by Weill Cornell Medicine investigators.

11 Mar 2026

Marburg virus enters human cells far more efficiently than Ebola

In a new study published in Nature, University of Minnesota researchers found that the Marburg virus, one of the world's deadliest pathogens with an average 73% fatality rate, is unusually efficient at getting inside human cells.

11 Mar 2026

Severe COVID and flu infections increase risk of lung cancer

Severe COVID-19 and influenza infections prime the lungs for cancer and can accelerate the disease's development, but vaccination heads off those harmful effects, new research from UVA Health's Beirne B. Carter Center for Immunology Research and UVA Comprehensive Cancer Center indicates.

11 Mar 2026

DNA origami vaccine platform shows promise against multiple infectious viruses

The COVID-19 pandemic brought messenger RNA (mRNA) vaccines to the forefront of global health care. After their clinical trial stages, the first COVID-19 mRNA vaccine was administered on 8 December 2020 and mathematical models suggest that mRNA vaccines prevented at least 14.4 million deaths from COVID-19 in the first year alone.

11 Mar 2026

EVA1A regulates fatty acid transporter CD36 in fatty liver disease

Metabolic Dysfunction-Associated Steatotic Liver Disease（MASLD） is characterized by excessive accumulation of lipids in hepatocytes and is closely associated with the rapid rise in insulin resistance, obesity, and diabetes prevalence, making it one of the most common chronic liver diseases worldwide.

9 Mar 2026

Researchers validate Mpox antibody test during outbreak in Rwanda

An antibody test for the infectious disease Mpox was successfully developed during the new clade 1b outbreak in Rwanda, the first time that an assay of its kind has been validated within this setting.

9 Mar 2026

Most pandemic viruses show little adaptation before infecting humans

A new University of California San Diego study published in Cell challenges a long-standing assumption about how animal viruses become capable of sparking human epidemics and pandemics.

9 Mar 2026

How somatic mutations shape disease and reveal new drug targets

Researchers reviewed how somatic mutations accumulate in normal and diseased tissues, showing that natural selection can expand clones that influence disease risk, tissue adaptation, or cellular resilience. The study proposes somatic genomics as a powerful strategy to uncover disease mechanisms and identify new therapeutic targets across multiple conditions.

8 Mar 2026