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 are Viral Clades?

What is a Viral Mutation?

Virus Infection in Other Species

Virus History

Jamestown Canyon Virus: An Emerging Arboviral Threat in Temperate Climates

What are Filoviruses?

Antiviral Immunity and COVID-19

Human Diseases Caused by Viruses

What Are Giant Viruses?

What is the Difference Between Bacteria and Viruses?

Virus Classification

See more featured articles »

Are Viruses a Lifeform?

Virus Microbiology

Virus Purification Methods

Virus Eradication, Extinction, and Elimination Explained

Virus Origins

Virus Uses in Virology

What is Vertical Transmission?

Latest Virus News and Research

RSV vaccine slashes hospitalizations in older adults in real-world trial

A large, real-world randomized trial in Denmark found that the RSVpreF vaccine reduced RSV-related hospitalizations in adults aged 60 and over by over 80%. The vaccine also showed protection against broader respiratory illness with a favorable safety profile.

15 Sep 2025

Early B cell response prevents Oropouche virus from reaching the brain

Research conducted on mice has identified that the rapid response of a specific type of defense cell is essential for controlling Oropouche virus infections and preventing serious neurological damage.

14 Sep 2025

UCLA team develops engineered antibodies to fight cytomegalovirus infection

A UCLA research team has found a new way to prompt the immune system to kill cells infected with cytomegalovirus (CMV), a life-threatening infection that is particularly deadly in immunocompromised people.

13 Sep 2025

ISSCR expresses concern over NIH decision on fetal tissue research funding

The International Society for Stem Cell Research (ISSCR), the largest professional organization of stem cell researchers from around the world, is concerned about a recent statement attributed to NIH that the agency will not renew research grants involving human fetal tissue (HFT), and that research with HFT is not conducted responsibly or transparently.

13 Sep 2025

Waning Japanese encephalitis immunity linked to more severe dengue illness

Scientists from Duke-NUS Medical School, in collaboration with researchers in Nepal, have found that waning immunity to Japanese encephalitis virus (JEV) may increase the risk of more severe dengue disease in humans.

13 Sep 2025

School closures during COVID created massive long-term costs with limited health benefits

School closures during the COVID-19 pandemic imposed enormous long-term costs while other measures delivered better health outcomes for far less money, according to new research led by Oxford University's Department of Statistics and the Leverhulme Centre for Demographic Science analysing non-pharmaceutical interventions in the United States.

13 Sep 2025

Postpartum mothers more likely to be cured of hepatitis C with bedside treatment

Hepatitis C, a bloodborne virus that damages the liver, can cause cirrhosis, liver cancer, liver failure and death if left untreated.

11 Sep 2025

Scientists uncover brain circuit that turns cravings into eating behavior

Researchers found that the bed nucleus of the stria terminalis integrates pleasure signals from central amygdala prodynorphin neurons and hunger signals from agouti-related peptide neurons to drive consumption. Manipulating this bed nucleus of the stria terminalis circuit bidirectionally altered food intake and body weight in mice.

11 Sep 2025

CRISPR-based therapeutic approach designed to treat fatal pediatric disease

Multisystemic smooth muscle dysfunction syndrome (MSMDS) is a rare condition associated with stroke, aortic dissection (tearing) and death in childhood.

11 Sep 2025

Antibody cocktail could change the way the world fights influenza

An unusual therapy developed at The Jackson Laboratory (JAX) could change the way the world fights influenza, one of the deadliest infectious diseases.

11 Sep 2025

Persistent COVID-19 in the intestines may drive inflammation in cancer patients

New research from the University of Minnesota Medical School is providing important insights into how COVID-19 persists in cancer patients even long after testing positive. The findings were recently published in iScience.

10 Sep 2025

Novel method accurately identifies therapeutic antibodies to treat infectious diseases

Scientists at Scripps Research have developed a novel method that uses artificial intelligence (AI) and advanced imaging techniques to more accurately and efficiently identify therapeutic antibodies to treat infectious diseases.

10 Sep 2025

Global climate warming fuels rising dengue burden across Asia and the Americas

Warmer weather across the globe is reshaping the landscape of human health. Case in point: dengue fever, a mosquito-borne disease once confined largely to the tropics which often brings flu-like symptoms and without proper medical care can escalate to severe bleeding, organ failure, and even death.

9 Sep 2025

Healthy newborns also face high risk of severe RSV infection

It is not only premature babies and children with underlying diseases who suffer from serious respiratory syncytial virus (RSV) infections.

9 Sep 2025

HPV-DeepSeek shows promise for early detection of head and neck cancer

Human papilloma virus (HPV) causes around 70% of head and neck cancers in the United States, making it the most common cancer caused by the virus, with rates increasing each year.

9 Sep 2025

Abselion launches AAVX and AAV9 Total Capsid Quantification Kits

Abselion, a pioneering life sciences technology company focused on simplifying biomolecule quantification, has expanded its product offering, with the launch of the AAVX Total Capsid Quantification Kit and the AAV9 Total Capsid Quantification Kit.

9 Sep 2025

Dengue infection leaves lasting genetic imprint on immunity

Just as a computer's operating system can be rewritten after a major update, dengue infection can 're-programme' the body's immune system, leaving a long-lasting genetic imprint that influences how people respond to future infections-an effect not seen with vaccination.

9 Sep 2025

Scientists identify key protein driving severe flu in older people

Scientists have discovered why older people are more likely to suffer severely from the flu, and can now use their findings to address this risk.

8 Sep 2025

Mushrooms deliver nutrition medicine and sustainability solutions in one package

This Food Science & Nutrition review highlights mushrooms as nutrient-rich functional foods packed with bioactive compounds that support human health. It explores their therapeutic, industrial, and environmental applications, from disease prevention and drug discovery to bioremediation and bioenergy.

8 Sep 2025