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 Origins

Jamestown Canyon Virus: An Emerging Arboviral Threat in Temperate Climates

What is Vertical Transmission?

Are Viruses a Lifeform?

Virus Eradication, Extinction, and Elimination Explained

Virus Purification Methods

Virus Classification

Virus Uses in Virology

What is the Difference Between Bacteria and Viruses?

Human Diseases Caused by Viruses

Virus Microbiology

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Antiviral Immunity and COVID-19

What are Viral Clades?

Virus Infection in Other Species

What is a Viral Mutation?

What Are Giant Viruses?

What are Filoviruses?

Virus History

Latest Virus News and Research

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

Study uncovers immune trigger behind vaccine-induced immune thrombocytopenia and thrombosis

A global research collaboration of scientists from McMaster University (Canada), Flinders University (Australia) and Universitätsmedizin Greifswald (Germany) uncovered why a small number of people developed dangerous blood clots after either receiving certain COVID‑19 vaccines or experiencing a natural adenovirus infection, and the answer lies in an unexpected case of misdirected targeting by the immune system.

11 Feb 2026

New strategy harnesses pre-existing antiviral immunity to boost anti-tumor responses

Because many different types of cancer cells overexpress programmed death-ligand 1 (PD-L1), this cell surface protein is a major target of cancer immunotherapy.

11 Feb 2026

One in five US women prefer at-home HPV screening

National data shows women who experience healthcare discrimination favor at-home HPV testing, raising questions about trust and access in screening guidelines.

11 Feb 2026

Study suggests shingles vaccine may help lower Alzheimer’s and dementia risk

A large observational electronic health record study found that older adults receiving the recombinant zoster vaccine showed substantially lower rates of diagnosed dementia compared with matched unvaccinated individuals. The association persisted after multiple sensitivity analyses, although causality remains unproven and longer follow-up is required given the long latency of dementia.

10 Feb 2026

Parvovirus infection disrupts nucleolar structure and cellular balance

Research at the University of Jyväskylä (Finland) reveals that autonomous parvoviruses, such as canine parvovirus, are highly capable of affecting the internal balance of the nucleolus.

10 Feb 2026

Choroid plexus enlargement in Long COVID signals cognitive risk

The increased size of, and lesser blood supply to, a key brain structure in patients with Long COVID tracks with known blood markers of Alzheimer's disease and greater levels of dementia, a new study finds.

10 Feb 2026

Preexisting flu immunity may offer baseline protection against avian influenza

Are seasonal flu antibodies also effective against avian flu? A team from the University of Geneva (UNIGE) has shown that a specific type of antibody associated with the former virus—already present throughout the population—may offer baseline protection against the latter.

10 Feb 2026

Influenza viruses can directly impair heart function

Mount Sinai researchers have identified a cellular mechanism linking infections from influenza A viruses (IAVs) to cardiovascular disease, providing critical insights on how influenza can damage the heart and increase the risk of a heart attack or other major cardiovascular event.

9 Feb 2026