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 History

What are Viral Clades?

Human Diseases Caused by Viruses

Jamestown Canyon Virus: An Emerging Arboviral Threat in Temperate Climates

What Are Giant Viruses?

What is the Difference Between Bacteria and Viruses?

Virus Microbiology

Virus Purification Methods

What are Filoviruses?

What is a Viral Mutation?

Virus Infection in Other Species

See more featured articles »

Virus Uses in Virology

Are Viruses a Lifeform?

Virus Origins

Virus Eradication, Extinction, and Elimination Explained

Virus Classification

What is Vertical Transmission?

Antiviral Immunity and COVID-19

Latest Virus News and Research

It’s a bird! It’s a plane! It’s a chemtrail? New conspiracy theory takes wing at Kennedy’s HHS

While plowing a wheat field in rural Washington state in the 1990s, William Wallace spotted a gray plane overhead that he believed was releasing chemicals to make him sick.

16 Oct 2025

CRISPR therapy shows promise against influenza in human lung chips

The Influenza A virus (IAV) has been the cause of six major flu pandemics, responsible for 50 to 100 million deaths globally.

15 Oct 2025

Immune checkpoint inhibitor TIGIT found to promote tissue healing

Immune checkpoint inhibitors are well known as a form of cancer treatment. Researchers at UZH have now identified a new, important function of these inhibitors: promotion of tissue healing.

15 Oct 2025

Combination strategy may optimize interferon-based therapy for chronic hepatitis B

Peginterferon-α treatment exhibits low rates of the serological conversion rate of hepatitis B e antigen (HBeAg) and the negative conversion rate of hepatitis B virus (HBV) DNA, with significant myelosuppression leading to treatment discontinuation in some patients.

14 Oct 2025

Estradiol and estriol may protect nerve function in multiple sclerosis

About 100,000 of the estimated million people in the United States with multiple sclerosis (MS) have a progressive form of the disease, with symptoms that worsen continuously or after periods of remission.

14 Oct 2025

Bird flu virus survives in raw-milk cheese for months

Findings indicate H5N1 virus stability in raw-milk cheese for 120 days, emphasizing the need for revised safety measures in dairy products to protect health.

14 Oct 2025

Multimodal nanocarriers offer targeted solutions for tumor treatment

Cancer remains a leading cause of global morbidity and mortality. Traditional therapies like chemotherapy and radiotherapy are often limited by their lack of specificity, leading to systemic toxicity and the emergence of drug resistance.

10 Oct 2025

HEPA purifiers do not fully reduce classroom viral exposure

In a secondary analysis of a study of 200 classrooms, Mass General Brigham researchers found respiratory viral exposures were still high in those with HEPA purifiers, suggesting additional interventions are needed.

10 Oct 2025

Natural nasal microbes offer broad-spectrum antiviral protection

Respiratory viral diseases pose severe threats to animal health and global food security, especially in intensive pig farming systems.

10 Oct 2025

Understanding the impact of chikungunya on children

Chikungunya is a vector-borne disease that affects both adults and children. While global efforts are ongoing to tackle chikungunya in adults, progress in addressing pediatric chikungunya remains inadequate.

10 Oct 2025

AI brings hope for cervical cancer detection in rural Africa

AI can be used to detect cervical cancer in women in resource-limited parts of the world. However, for this method to work, investments are needed in healthcare staff, reliable supply chains and trust in these communities.

10 Oct 2025

New gene therapy reverses symptoms of SYNGAP1-related disorders in mice

In an exciting scientific first, researchers at the Allen Institute successfully designed a new gene therapy that reversed symptoms related to SYNGAP1-related disorders (SRD) in mice.

9 Oct 2025

Nanoparticle vaccine shows promise in preventing multiple cancers in mice

A study led by University of Massachusetts Amherst researchers demonstrates that their nanoparticle-based vaccine can effectively prevent melanoma, pancreatic and triple-negative breast cancer in mice.

9 Oct 2025

Engineered virus therapy triggers powerful immune responses in glioblastoma

A new study led by Break Through Cancer's Accelerating Glioblastoma (GBM) Therapies Through Serial Biopsies TeamLab has revealed that an engineered virus therapy, CAN-3110, triggered powerful immune responses deep inside glioblastoma tumors that were invisible to standard imaging like MRI, according to early analyses of two patients with recurrent GBM.

9 Oct 2025

Study reveals large differences in knowledge about ticks between countries

Ticks are found all over the world. There are more than 900 species, and many of them pass on dangerous diseases to both humans and animals.

9 Oct 2025

PlasmidFactory and Fraunhofer IZI join forces to advance non-viral cell and gene therapies

PlasmidFactory GmbH and the Fraunhofer Institute for Cell Therapy and Immunology IZI have signed a Memorandum of Understanding to combine expertise in cell therapy process development and GMP manufacturing, aiming to accelerate non-viral cell and gene therapies for the benefit of patients.

From PlasmidFactory GmbH 9 Oct 2025

Nasal spray of gold nanoparticles delivers lithium directly to the brain

In the form of a 'nasal spray', tiny gold particles act as carriers, delivering a treatment directly to the brain: developed by scientists at the Università Cattolica Rome campus/Fondazione Policlinico Universitario A. Gemelli IRCCS, a new nanotechnological device for the treatment and prevention of neuropsychiatric and neurodegenerative diseases.

8 Oct 2025

Repeated sampling offers insight into glioblastoma therapy response

A multi-institutional study from the Accelerating GBM Therapies Through Serial Biopsies TeamLab, led by investigators from the Mass General Brigham Cancer Institute, found that serially testing tumor samples can help detect when a cancer treatment is activating the immune system in recurrent glioblastoma (GBM), even when traditional imaging measures cannot.

8 Oct 2025

Brainstem damage found to be behind long-lasting effects of severe Covid-19

Damage to the brainstem - the brain's 'control center' - is behind long-lasting physical and psychiatric effects of severe Covid-19 infection, a study suggests.

8 Oct 2025

Engineered CAR-NK cells show enhanced cancer killing and immune evasion

One of the newest weapons that scientists have developed against cancer is a type of engineered immune cell known as CAR-NK (natural killer) cells. Similar to CAR-T cells, these cells can be programmed to attack cancer cells.

8 Oct 2025