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 Uses in Virology

Virus History

Antiviral Immunity and COVID-19

Virus Purification Methods

What are Filoviruses?

Virus Infection in Other Species

Jamestown Canyon Virus: An Emerging Arboviral Threat in Temperate Climates

What Are Giant Viruses?

What is a Viral Mutation?

What are Viral Clades?

See more featured articles »

Virus Origins

What is Vertical Transmission?

Human Diseases Caused by Viruses

Virus Classification

What is the Difference Between Bacteria and Viruses?

Virus Microbiology

Virus Eradication, Extinction, and Elimination Explained

Latest Virus News and Research

Covid vaccinations remain vital to protect global heart health

Regular Covid vaccinations should continue worldwide to reduce cardiac risks associated with the virus - according to new research from the University of East Anglia.

17 Sep 2025

Rising threat of sexually transmitted gut infections demands stronger prevention strategies

It's time to develop more effective ways to control and prevent sexually transmitted gut infections, urge the authors of an article appearing today in Clinical Microbiology Reviews, a journal of the American Society of Microbiology.

17 Sep 2025

Watch: Fired CDC chief says RFK Jr. demanded she roll back vaccine policies without evidence

Susan Monarez, the former director of the Centers for Disease Control and Prevention, testified before the Senate Health, Education, Labor, and Pensions Committee on Sept. 17 in her first public remarks since she was fired.

17 Sep 2025

Florida chickens help scientists forecast West Nile virus outbreaks

A new study has significant bearing on the hackneyed joke about chickens and their numerous reasons for crossing roads.

17 Sep 2025

Innovative biosensor can detect airborne viruses in real time

A research team from Universitat Politècnica de València (UPV) and Universitat de València (UV) has developed an innovative biosensor capable of detecting airborne viruses in real time and at low cost, without the need for chemical markers or laboratory procedures.

17 Sep 2025

Soap shortages undermine global hand hygiene efforts

A lack of soap is the most often reported barrier to effective hand hygiene-key to curbing the spread of infection-in shared community spaces, such as households, schools, and public places, finds a systematic review of the available research, published in the open access journal BMJ Global Health.

17 Sep 2025

CRISPR-GPT helps scientists to generate designs, analyze data and troubleshoot design flaws

Stanford Medicine researchers have developed an artificial intelligence tool to help scientists better plan gene-editing experiments.

16 Sep 2025

AI breakthrough offers a new way to predict and visualize disease processes

To solve a problem, we have to see it clearly. Whether it's an infection by a novel virus or memory-stealing plaques forming in the brains of Alzheimer's patients, visualizing disease processes in the body is the first step toward alleviating human suffering. It's also often the most difficult and costly.

16 Sep 2025

Researchers uncover how HIV-1 uses RNA:DNA hybrids to integrate into the genome

Researchers at the German Center for Infection Research (DZIF) at Heidelberg University Hospital have decoded a previously unknown mechanism by which HIV-1 selects its integration targets in the human genome.

16 Sep 2025

Decline in pediatric rescue breathing increased deaths during the pandemic

Cardiac arrest happens when the heart stops pumping blood properly, cutting off oxygen to the brain and other vital organs.

16 Sep 2025

Study uncovers the tradeoff between fast immune defense and long-term inflammation

Some of our biggest threats can come in the tiniest forms-viruses and bacteria. Thankfully, we are born with a built-in defense system, our innate immune system that protects us in our youth but can turn against us as we age.

16 Sep 2025

Novel biotechnical vector integrates viral and synthetic features for targeted cancer therapy

Gene therapy offers the possibility of addressing cancer at its molecular roots by targeting disease-causing genes rather than relying solely on surgery, chemotherapy, or radiotherapy.

16 Sep 2025

RFK Jr.’s vaccine panel expected to recommend delaying hepatitis B shot for children

A key federal vaccine advisory panel whose members were recently replaced by Health and Human Services Secretary Robert F. Kennedy Jr. is expected to vote to recommend delaying until age 4 the hepatitis B vaccine that's currently given to newborns, according to two former senior Centers for Disease Control and Prevention officials.

16 Sep 2025

An HIV outbreak in Maine shows the risk of Trump’s crackdown on homelessness and drug use

Penobscot County, Maine, is grappling with the largest HIV outbreak in the state's history. Home to Bangor, a city of roughly 32,000, the county has identified 28 new cases over nearly two years.

16 Sep 2025

FUJIFILM Biosciences introduces BalanCD HEK293 perfusion a medium to enable gene therapy production

FUJIFILM Biosciences, a global leader in the innovation and manufacture of cell culture solutions for the Life Science market, today announced the commercial launch of BalanCD HEK293 Perfusion A.

15 Sep 2025

Philippines unveils new technologies to detect and manage African Swine Fever

Three new technologies to detect and manage African Swine Fever have been unveiled in the Philippines amid ongoing concerns about a vaccine imported from Vietnam.

15 Sep 2025

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