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 is the Difference Between Bacteria and Viruses?

Virus Uses in Virology

What are Filoviruses?

What are Viral Clades?

Virus Infection in Other Species

What is a Viral Mutation?

Virus Classification

Human Diseases Caused by Viruses

What is Vertical Transmission?

Antiviral Immunity and COVID-19

What Are Giant Viruses?

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Virus Microbiology

Virus History

Virus Purification Methods

Virus Eradication, Extinction, and Elimination Explained

Are Viruses a Lifeform?

Virus Origins

Latest Virus News and Research

Mapping the T cell response to Chikungunya virus

A new study, published recently in Nature Communications, offers the first-ever map of which parts of Chikungunya virus trigger the strongest response from the body's T cells.

3 Jul 2025

Hepatitis E virus also attacks organs other than the liver, study finds

A research team from Bochum and Hannover shows that the hepatitis E virus also attacks organs other than the liver.

3 Jul 2025

Blood viral load predicts severity of mpox symptoms

In August 2024, the World Health Organization declared a second "Public Health Emergency of International Concern" for mpox.

3 Jul 2025

Twice-yearly injection could transform HIV prevention efforts

Preventative therapies for HIV-1 (Human Immunodeficiency Virus type 1) have made leaps and bounds over the past decade. A once-daily pill named PrEP, or pre-exposure prophylaxis, has been a stalwart for HIV prevention-but only if people take it consistently and can routinely access a pharmacy.

3 Jul 2025

Study finds significant uptick in chronic digestive disorders during COVID-19 pandemic

A study led by Cedars-Sinai investigators uncovered a significant uptick in chronic digestive disorders, like irritable bowel syndrome, during the COVID-19 pandemic.

3 Jul 2025

Gene therapy brings back hearing in young and adult deaf patients

Gene therapy can improve hearing in children and adults with congenital deafness or severe hearing impairment, a new study involving researchers at Karolinska Institutet reports.

3 Jul 2025

Cornell scientists use natural cell proteins to track molecular behavior

Cornell researchers have found a new and potentially more accurate way to see what proteins are doing inside living cells - using the cells' own components as built-in sensors.

2 Jul 2025

Mature dendritic cell vesicles enhance influenza vaccine effectiveness

Influenza hemagglutinin subunit vaccines are more effective and offer better cross protection against various influenza virus challenges when combined with a mucosal adjuvant that enhances the body's immune response, according to a study by researchers in the Institute for Biomedical Sciences at Georgia State University.

2 Jul 2025

As mosquito season peaks, officials brace for new normal of dengue cases

As summer ushers in peak mosquito season, health and vector control officials are bracing for the possibility of another year of historic rates of dengue.

2 Jul 2025

HIV treatment linked to risk of early knee osteoarthritis

Acquired immune deficiency syndrome, or AIDS, caused by the human immunodeficiency virus (HIV), weakens the body's immune system and can be life-threatening if left untreated.

1 Jul 2025

Vaccination plays key role in preventing cardiovascular events after infection

Today, a new ESC Clinical Consensus Statement published in the European Heart Journal discusses the key role of vaccination in preventing cardiovascular events following various viral and bacterial infections.

1 Jul 2025

Macrophage-derived lipocalin 2 drives severe pneumonia in SARS-CoV-2 infection

Since the emergence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), understanding the mechanisms underlying severe pneumonia has remained a major research challenge.

1 Jul 2025

How underreporting masks the real impact of RSV in older populations

Research shows RSV leads to high hospitalization rates in adults, emphasizing the importance of enhanced surveillance and diagnostic measures in healthcare.

1 Jul 2025

Researchers link genetic ancestry to severity of dengue fever

For the first time, the extreme variability in dengue fever has been linked to a biological mechanism, potentially opening doors to new treatments and vaccines for the most common mosquito-borne disease worldwide.

30 Jun 2025

Shingles and RSV vaccines with AS01 adjuvant reduce dementia risk

Researchers found that older adults who received AS01-adjuvanted shingles or RSV vaccines had a significantly lower risk of developing dementia within 18 months compared to flu vaccine recipients. The protective effect is likely linked to the AS01 adjuvant itself, highlighting new avenues for dementia prevention.

30 Jun 2025

GATE complex discovery sheds light on CMV's evasion of immune defenses

New research from the University of Pittsburgh School of Medicine and La Jolla Institute for Immunology, published today in Nature Microbiology, reveals an opportunity for developing a therapy against cytomegalovirus (CMV), the leading infectious cause of birth defects in the United States.

30 Jun 2025

WHO Scientific Advisory Group for the Origins of Novel Pathogens reports on SARS-CoV-2 origins

The WHO Scientific Advisory Group for the Origins of Novel Pathogens (SAGO), a panel of 27 independent, international, multidisciplinary experts, today published its report on the origins of SARS-CoV-2, the virus responsible for the COVID-19 pandemic.

27 Jun 2025

Limiting carcinogen exposure could mitigate liver cancer risk for people with HBV infection

Hepatitis B virus (HBV) infection is known to be associated with the risk of hepatocellular carcinoma (HCC), but how and why they are connected remains unknown.

27 Jun 2025

Beetle-inspired tuberculosis testing device offers accurate detection for people with HIV

Current tuberculosis infection tests struggle to detect the disease in those with HIV. A common co-infection, HIV can hide TB from traditional tests by eliminating the immune cells relied upon to sound the alarm.

27 Jun 2025

Kennedy’s vaccine advisers sow doubts as scientists protest US pivot on shots

As fired and retired scientists rallied outside in the Atlanta heat, an advisory panel that Robert F. Kennedy Jr. handpicked to replace experts he'd fired earlier met inside the Centers for Disease Control and Prevention's headquarters to plan a more skeptical vaccine future.

27 Jun 2025