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

Virus Eradication, Extinction, and Elimination Explained

Human Diseases Caused by Viruses

What are Filoviruses?

What Are Giant Viruses?

Antiviral Immunity and COVID-19

Are Viruses a Lifeform?

Virus Purification Methods

Virus Microbiology

What is Vertical Transmission?

See more featured articles »

Virus Origins

Virus Infection in Other Species

Jamestown Canyon Virus: An Emerging Arboviral Threat in Temperate Climates

Virus Classification

What are Viral Clades?

Virus History

What is a Viral Mutation?

Latest Virus News and Research

Purdue researchers discover new therapeutic target for triple-negative breast cancer

A Purdue University team led by Kyle Cottrell has discovered a new therapeutic target for triple-negative breast cancer.

27 Jan 2026

Faster hepatitis C treatment with interdisciplinary primary care

Hepatitis C virus treatment is increasingly being offered in primary care because medications now require less frequent monitoring and have fewer adverse effects.

27 Jan 2026

Trump policies at odds with emerging understanding of covid’s long-term harm

27 Jan 2026

Game-changing discovery reveals how viruses may trigger ALS development

A large, multidisciplinary team led by researchers from Texas A&M University has made a potentially game-changing discovery about the development of devastating motor neuron diseases like amyotrophic lateral sclerosis (ALS).

27 Jan 2026

Diagnostic prognostic and therapeutic relevance of PIVKA-II in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) remains a leading cause of cancer-related mortality worldwide, particularly in regions with high hepatitis B virus prevalence.

24 Jan 2026

Evidence of African lineage Zika virus circulation in neotropical primates in Southern Brazil

Announcing a new article publication for Zoonoses journal. Mosquito-borne orthoflaviviruses are maintained in cycles involving mosquito and vertebrate hosts.

23 Jan 2026

Ageing slows brain protein clearance and shifts synaptic waste to microglia

Ageing slows neuronal protein degradation in mice, leading to widespread accumulation and aggregation of long-lived proteins, particularly at synapses. As neuronal clearance declines, microglia selectively accumulate synaptic proteins, suggesting a compensatory but potentially strained proteostasis pathway in the ageing brain.

22 Jan 2026

Survey shows growing public familiarity with RSV vaccines and antibody injections

Amid a surprisingly severe flu season and a Covid-19 resurgence, those highly contagious respiratory illnesses are drawing the largest share of media coverage and public attention.

21 Jan 2026

Study reveals immune traffic controller hijacked by common virus

In a major scientific breakthrough, researchers from Monash University and the Lions Eye Institute have discovered a tissue protein that acts as a central 'traffic controller' for immune cells and can be hijacked by a virus to weaken immune responses.

21 Jan 2026

Study clarifies role of steroids in treating HSV encephalitis

A major UK clinical trial has shown that adding the corticosteroid dexamethasone to standard antiviral treatment for encephalitis (brain inflammation), caused by herpes simplex virus (HSV) does not improve long-term outcomes overall, although early use may lead to better recovery, and the treatment is safe for patients in whom encephalitis is suspected.

21 Jan 2026

Shingles vaccination is linked to slower biological aging in older adults

This population-based study of U.S. adults aged 70 and older found that shingles vaccination was associated with slower epigenetic and transcriptomic aging, as well as lower systemic inflammation. No significant associations were observed for neurodegeneration or cardiovascular biomarkers, highlighting domain-specific molecular effects rather than broad clinical changes.

21 Jan 2026

As US is poised to lose measles-free status, RFK’s new CDC deputy downplays its significance

After a year of ongoing measles outbreaks that have sickened more than 2,400 people, the United States is poised to lose its status as a measles-free country.

21 Jan 2026

COVID-19 severity is linked to changes in mitochondrial DNA methylation

This study examined mitochondrial and nuclear-encoded mitochondrial DNA methylation in Indian patients with severe COVID-19 and found region-specific differential methylation linked to disease severity. Pathway analyses and protein assays implicated disrupted mitochondrial metabolism and dynamics, suggesting a role for mitochondrial epigenetic regulation in COVID-19 pathophysiology.

20 Jan 2026

Measles resurgence: Global Virus Network calls for urgent action

The Global Virus Network (GVN), representing eminent human and animal virologists from more than 90 Centers of Excellence and Affiliates in over 40 countries dedicated to advancing research, collaboration, and pandemic preparedness, expresses deep concern regarding the ongoing resurgence of measles in the United States and around the globe.

20 Jan 2026

GOP promotes MAHA agenda in bid to avert midterm losses. Dems point to contradictions.

When a "Make America Healthy Again" summit was held at the posh Waldorf Astoria in Washington, the line of attendees stretched down the block.

20 Jan 2026

The challenge of tracking asymptomatic Mpox

The mpox virus appears to be circulating silently in parts of Nigeria, in many cases without the symptoms typically associated with the disease, according to new research led by scientists from the University of Cambridge and partners in Nigeria. The findings may have implications for controlling the spread of the disease.

20 Jan 2026

Shingles vaccination may slow biological aging in older adults

Shingles vaccination not only protects against the disease but may also contribute to slower biological aging in older adults, according to a new USC Leonard Davis School of Gerontology study.

20 Jan 2026

Interferon response key to fighting rhinovirus infections in nasal passages

When a rhinovirus, the most frequent cause of the common cold, infects the lining of our nasal passages, our cells work together to fight the virus by triggering an arsenal of antiviral defenses.

19 Jan 2026

Elevated tau in Long COVID patients raises risk for neurodegenerative diseases

A study of 227 individuals who experienced neuro cognitive difficulties post COVID-19 infection – such as headaches, vertigo, balance dysregulation, changes in taste/smell, and brain fog – displayed a significant increase in their blood plasma of a crucial protein called tau, which is found in nerves and especially in the brain.

19 Jan 2026

Purdue-developed LENN system enhances stability and targeting of mRNA cancer therapies

Published, peer-reviewed research shows a patent-pending, virus-mimicking platform technology developed at Purdue University improves upon traditional methods of targeting bladder cancer cells with messenger RNA (mRNA) therapies.

16 Jan 2026