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?

Virus Classification

Virus Origins

Virus Purification Methods

What is a Viral Mutation?

What Are Giant Viruses?

Virus Uses in Virology

Virus Eradication, Extinction, and Elimination Explained

Are Viruses a Lifeform?

Antiviral Immunity and COVID-19

What is Vertical Transmission?

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Human Diseases Caused by Viruses

What is the Difference Between Bacteria and Viruses?

What are Filoviruses?

Virus History

Virus Infection in Other Species

Jamestown Canyon Virus: An Emerging Arboviral Threat in Temperate Climates

Virus Microbiology

Latest Virus News and Research

Periodontal bacteria trigger bone density reduction via the gut

Periodontitis, a chronic inflammatory disease of the gums, affects hundreds of millions of people worldwide and is increasingly linked to systemic disorders beyond the oral cavity.

4 Mar 2026

Study uncovers a biological cause for persistent taste loss after COVID-19

Some individuals have experienced a loss of taste long after a COVID-19 infection has subsided. Researchers from the Swedish University of Agricultural Sciences, Uppsala University and the University of Colorado have now shown that this may be due to a disruption in taste cells that would otherwise give rise to experiences of sweet, bitter or umami.

4 Mar 2026

Natural fungal supplement strengthens vaccine protection without increasing side effects

Researchers at University California San Diego School of Medicine have found that a natural fungal supplement taken at the time of COVID-19 vaccination reduced short-term vaccine side effects and helped antibodies - the body's natural immune defenders - last longer in people who had not previously been exposed to the virus.

4 Mar 2026

New HIV-seq tool advances understanding of persistent viral reservoirs

For people living with human immunodeficiency virus (HIV), life-saving antiretroviral therapy keeps their HIV-infected immune cells from making new copies of the virus, preventing illness and transmission.

3 Mar 2026

New strategy targets Porphyromonas gingivalis without harming healthy microbes

For years, treating gum disease has meant scraping away plaque, cutting out damaged tissue or turning to antibiotics that kill bacteria indiscriminately.

3 Mar 2026

Leading CROs and CDMOs turn to mass photometry for rapid protein, mRNA and viral vector analytics

Refeyn, developer of pioneering mass photometry technology, expands its global adoption across contract research organizations (CROs) and contract development and manufacturing organizations (CDMOs).

3 Mar 2026

Research suggests new therapeutic targets for broad-spectrum antiviral drugs

Coronaviruses not only use the machinery of the human cells they infect: they modify it to achieve optimal conditions to produce viral proteins and thus spread more quickly. This is the main conclusion of a study by Pompeu Fabra University published in Nature Communications.

3 Mar 2026

Persistent taste dysfunction after COVID 19 linked to cellular abnormalities

Scientists have identified molecular and structural changes in taste buds that may explain why a small subset of people experience long-term taste loss after COVID-19 infection.

2 Mar 2026

Non-invasive immune monitoring via bandage-like microneedle patches

Researchers at The Jackson Laboratory (JAX), in collaboration with the Massachusetts Institute of Technology (MIT), have developed the first bandage-like microneedle patch that can sample the body's immune responses painlessly from the skin.

2 Mar 2026

New structural insights pave way for hantavirus vaccines

Hantaviruses, transmitted from rodents to people, have a death rate approaching 40%. They're found around the world, and because there are no approved vaccines or treatments, they're among the pathogens of highest concern for future pandemics.

27 Feb 2026

WHO updates 2026-2027 flu vaccine composition amidst viral evolution

The World Health Organization (WHO) today announced recommendations for the viral composition of influenza (or "flu") vaccines for the 2026-2027 northern hemisphere influenza season.

27 Feb 2026

Denmark achieves historic elimination of mother-to-child HIV and syphilis transmission

The World Health Organization (WHO) has certified Denmark for the elimination of mother-to-child transmission (EMTCT) of HIV and syphilis, recognizing the country's sustained commitment to ensuring every child is born free of these infections.

27 Feb 2026

New daily tablet simplifies long-term HIV care

A new, daily oral tablet that combines two current HIV treatment medications, bictegravir and lenacapavir (BIC/LEN), may be able to effectively replace more complicated HIV treatment regimens used by people living with HIV who are long-term survivors, according to the results of a new phase 3 clinical trial published in The Lancet.

26 Feb 2026

New single pill regimen simplifies treatment for resistant HIV

A phase 3 clinical trial, led by Professor Chloe Orkin of Queen Mary University of London, has shown that a new, daily oral tablet that combines two current HIV treatment medications – bictegravir and lenacapavir (BIC/LEN) – may simplify treatment significantly for people with HIV who currently take very complex treatments.

25 Feb 2026

RSV and COVID-19 trigger different immune responses in infants

Young infants hospitalized with respiratory syncytial virus (RSV) often become much sicker compared to those infected with SARS-CoV-2, the virus that causes COVID-19.

25 Feb 2026

Prior COVID infection increases kidney disease risk

Approximately one in seven adults in the United States has kidney disease, where the organs responsible for filtering waste and excess water from the blood are damaged, according to the Centers for Disease Control and Prevention.

25 Feb 2026

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