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.

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What Are Giant Viruses?

Jamestown Canyon Virus: An Emerging Arboviral Threat in Temperate Climates

What is Vertical Transmission?

What are Filoviruses?

Virus Purification Methods

Are Viruses a Lifeform?

Virus Origins

Human Diseases Caused by Viruses

Virus Microbiology

Virus Uses in Virology

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What is a Viral Mutation?

Virus History

Antiviral Immunity and COVID-19

What are Viral Clades?

What is the Difference Between Bacteria and Viruses?

Virus Classification

Virus Infection in Other Species

Latest Virus News and Research

New approach identified for treating infections with Hepatitis E virus

Instead of directly attacking the virus, the compound acts on the host cell and prevents infection.

23 Apr 2026

Astrocytes form complex networks across the mouse brain

Cells long thought to play a secondary role in brain function build their own far-reaching connections, a new study in mice showed. These pathways appear to connect distant regions in ways that have not been mapped before.

23 Apr 2026

Bioengineered chewing gum reduces cancer-linked oral microbes

Researchers led by Henry Daniell of the School of Dental Medicine have shown that extracts from bioengineered chewing gum reduce the levels of three microbes known to be associated with head and neck squamous cell cancer (HNSCC), paving the way for more effective and affordable therapies.

23 Apr 2026

New gene therapy improves hearing in patients with rare genetic deafness

A new international study co-led by investigators from Mass General Brigham and the Eye & ENT Hospital of Fudan University shows that a gene therapy for a rare form of genetic deafness successfully restored hearing in most participants, with results lasting up to 2.5 years.

23 Apr 2026

COVID-19 virus not retained in placenta after maternal recovery

A new Yale study published in JAMA Network Open finds that the virus that causes COVID-19 does not linger in placental tissue weeks to months after a pregnant woman recovers from infection - offering important reassurance for clinicians and patients alike.

22 Apr 2026

Rising rotavirus cases highlight importance of childhood vaccination

With a rising number of rotavirus cases being reported across the country and in New Jersey this spring, experts from Hackensack Meridian Children's Health are urging parents to ensure their children are vaccinated against this common and potentially severe illness.

21 Apr 2026

Millions of Americans with hepatitis C still remain untreated, analysis reveals

Millions of Americans are still battling potentially deadly hepatitis C even though they could be cured with antiviral drugs they are not receiving, a new analysis reveals.

21 Apr 2026

Early immune responses linked to broadly neutralizing antibodies against HIV

Some people living with HIV develop antibodies capable of neutralizing many different strains of the virus. New research links this to immune responses that occur early in infection.

21 Apr 2026

Study creates genetic roadmap of how HIV virus interacts with human cells

The human immunodeficiency virus (HIV), which is the cause of AIDS, is a master of deception, using just nine genes to hijack the complex cellular machinery of the human body.

20 Apr 2026

Study links long COVID in kids to worse grades and attention problems

A large NIH-funded RECOVER-Pediatrics study found that children and adolescents meeting the long COVID research threshold were more likely to have caregiver-reported worsening grades, attention difficulties, reduced enjoyment with friends, and greater IEP involvement than peers below the threshold. The findings suggest that pediatric long COVID may affect school and social functioning during key developmental years, although the cross-sectional design does not establish causation.

20 Apr 2026

Antiretroviral therapy reduces biological aging in people living with HIV

A major study presented today at ESCMID Global 2026 has found that antiretroviral therapy (ART) reduces accelerated biological ageing in people with HIV (PWH) by nearly four years, a finding that could transform how clinicians monitor HIV treatment and long-term health outcomes.

20 Apr 2026

UPV researchers develop rapid sensor for detecting active tuberculosis

A research team at UPV is leading the development of a sensor that paves the way for the rapid, selective and cost-effective detection of active tuberculosis.

20 Apr 2026

New handbook aims to improve pandemic modeling and decision making

As the COVID-19 pandemic wreaked havoc and lives were at stake, the advice experts gave to decision-makers became indispensable.

17 Apr 2026

AGA update calls for better surveillance of hepatocellular carcinoma

A new update from the American Gastroenterological Association (AGA) urges stronger prevention efforts and better early-detection tools for hepatocellular carcinoma (HCC), the leading cause of cancer-related death in patients with cirrhosis, and the third most common cause of cancer-related death worldwide.

17 Apr 2026

Scientists find unexpected immune pathways for mRNA cancer vaccines

The advent of mRNA vaccines against SARS-CoV-2 in 2020 changed the course of the COVID-19 pandemic.

17 Apr 2026

Childhood flu infection leaves lasting immune imprint

A study reveals how childhood flu infections impact long-term mortality risk, highlighting implications for vaccination and future outbreak management.

17 Apr 2026

Hidden viral reservoirs in tonsils may explain school-year respiratory outbreaks

A study conducted at the University of São Paulo (USP) in Brazil reveals that tissues such as the tonsils and adenoids can serve as hiding places for the rhinovirus, which causes the common cold and is responsible for most respiratory infections worldwide.

17 Apr 2026

Superficial skin exposures pose a higher rabies risk than previously thought

While it was previously thought that keratinocytes (skin cells) were only passive conductors that allow the rabies virus to pass through, novel research reveals that these cells play a much more active role. The findings of a new study in the Journal of Investigative Dermatology (JID), published by Elsevier, provide direct evidence that keratinocytes can support viral replication and transmit the rabies virus to neurons. The investigators offer a mechanistic explanation for how superficial skin exposures from scratches or minor bites by dogs and bats can lead to neuroinvasion, contributing to the risk of infection.

16 Apr 2026

New flu vaccine approach targets multiple virus strains

Doctors recommend getting your flu shot annually, since the specific influenza strain it targets varies from year to year. But what if the shot could be more effective while protecting against more strains?

15 Apr 2026