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 Classification

Jamestown Canyon Virus: An Emerging Arboviral Threat in Temperate Climates

Human Diseases Caused by Viruses

Virus Microbiology

What is a Viral Mutation?

Virus History

What is the Difference Between Bacteria and Viruses?

Antiviral Immunity and COVID-19

What are Viral Clades?

Virus Purification Methods

What are Filoviruses?

See more featured articles »

Virus Origins

What is Vertical Transmission?

Virus Infection in Other Species

What Are Giant Viruses?

Are Viruses a Lifeform?

Virus Eradication, Extinction, and Elimination Explained

Virus Uses in Virology

Latest Virus News and Research

Host-targeting drugs offer new way to fight flu resistance

A drug that targets the host rather than the virus could get around the problem of anti-viral resistance. Every year, hundreds of thousands of people die of seasonal influenza, caused by infection with influenza A and B viruses.

1 Sep 2026

New scLS algorithm advances gene expression trajectory analysis

Single-cell RNA sequencing (scRNA-seq) is a method to measure gene expression of individual cells, allowing observation of various cellular processes, including cell differentiation, the cell cycle, and stimulus-response for each unique cell instead of averaging across millions of cells.

1 Sep 2026

Review highlights challenges in managing childhood enterovirus infections

Enteroviruses (EVs) are a diverse group of viruses and a common cause of multiple infections in children.

1 Sep 2026

Immunotherapy shows potential for treating rising gynecological tumors

Gynecological tumors, including cervical cancer (CC), endometrial cancer (EC), and ovarian cancer (OC), represent a significant global health burden for women.

1 Sep 2026

New method based on human blood simplifies mRNA drug development

mRNA-based drugs are emerging as the drug of the future for a wide range of diseases, but they are difficult and time-consuming to develop.

1 Sep 2026

Antiviral COVID-19 drug shows no benefit for Long COVID

Results from a clinical trial funded by the National Institutes of Health (NIH) and published today in the journal Lancet Infectious Diseases show that the antiviral drug, PAXLOVID, commonly prescribed to treat acute COVID-19, does not have an impact on Long COVID symptoms when compared to placebo.

1 Sep 2026

Seminal fluid facilitates monkeypox virus entry into human cells

Monkeypox virus used to be transmitted predominantly from animals to humans. In recent years, however, new virus variants have become increasingly capable of spreading from person to person.

31 Aug 2026

Mathematical model shows combined strategies greatly reduce Mpox transmission

Mpox (formerly Monkeypox), a viral zoonotic disease, remains a global public health concern because it can spread between animals and humans and among people.

31 Aug 2026

Newly discovered lung immune cells could transform future flu vaccine design

Influenza continues to cause major illness each year in the United States, leading to more than 35,000 deaths annually. Children, older adults, pregnant individuals, people with weakened immune systems, and those with chronic conditions such as heart disease, metabolic disorders, and cancer are especially vulnerable.

31 Aug 2026

Stanford scientists develop an ultracompact gene activation tool

The ability to precisely adjust the expression of genes inside the human body - ramping up protective ones and tamping down harmful ones - holds enormous potential for treating and preventing disease.

28 Aug 2026

Virginia Tech virologist wins federal award to study cellular virus battles

Every time your body fights a virus, cells are making split-second decisions that determine whether an infection spreads or stops.

28 Aug 2026

African Bundibugyo ebolavirus vaccine candidate to be advanced to clinical trials

Leading African biopharmaceutical company Minapharm Group, headquartered in Egypt with subsidiaries in Berlin, will receive up to US$16.5 million from the Coalition for Epidemic Preparedness Innovations (CEPI) to advance the development of a Bundibugyo ebolavirus vaccine candidate, strengthening efforts to develop vaccines to combat the fastest-growing and second-largest Ebola outbreak on record affecting the Democratic Republic of the Congo (DRC).

28 Aug 2026

The US switch in shingles vaccines revealed an unexpected heart health pattern

In a natural experiment involving 72,920 propensity-matched US adults aged 60 years and older, recombinant shingles vaccination was associated with a 9% lower cardiovascular disease burden over seven years compared with the live attenuated vaccine. Lower burdens of ischemic heart disease and heart failure were seen in both sexes, while ischemic stroke was significantly lower only among men, supporting further clinical trials and mechanistic studies

27 Aug 2026

Experimental vaccine protects against Zika virus through T cells alone

Zika virus has been spreading for decades, but it first grabbed worldwide headlines in 2016. That February, with an outbreak sweeping the Americas, the World Health Organization (WHO) declared the surge in Zika-linked birth defects a "public health emergency of international concern"-a designation which lasted until that November.

26 Aug 2026

New artificial lung mimics breathing and alveolar movement

Almost everyone has blown a soap bubble through a straw at least once. Inspired by this thin soap bubble film, an "artificial lung that breathes" like a real lung has been developed.

25 Aug 2026

Visual storytelling transforms scientific evidence into meaningful public health action

Even as the scientific community has reached broad consensus that infectious pathogens, such as viruses, can spread through airborne transmission in virus-laden aerosols, one fundamental challenge remains.

25 Aug 2026

Yeast-based nanoparticle vaccine could make annual flu shots obsolete

The world mostly relies on an 80-year-old method for producing flu vaccines from chicken eggs - a slow, costly process that struggles to quickly adapt to new, mutant strains.

24 Aug 2026

Nanoparticle vaccine offers long-lasting protection against multiple flu strains

A new, nanoparticle vaccine could one day grant patients immunity to the flu with fewer trips to the doctor and without health officials correctly guessing which flu strains will become dominant each year.

24 Aug 2026

AI predicts vaccine response based on pre-existing antibody patterns

Vaccines protect most people from serious illness, but the strength of that protection can vary considerably from one person to another. A new study led by Arizona State University helps us understand why.

20 Aug 2026

First 24 hours shape the body's antiviral defense response

Age, genetics and lifestyle are known to influence how people respond to viral infections. Scientists also know that differences in immune response play an important role, but exactly how these factors shape the course of an infection has remained unclear.

19 Aug 2026