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

Virus Eradication, Extinction, and Elimination Explained

Virus Uses in Virology

Virus Purification Methods

Virus Origins

Are Viruses a Lifeform?

Virus Microbiology

What are Filoviruses?

Virus Infection in Other Species

What is the Difference Between Bacteria and Viruses?

Human Diseases Caused by Viruses

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Antiviral Immunity and COVID-19

Jamestown Canyon Virus: An Emerging Arboviral Threat in Temperate Climates

What Are Giant Viruses?

What is a Viral Mutation?

What are Viral Clades?

What is Vertical Transmission?

Virus History

Latest Virus News and Research

Nasal spray vaccine prevents infection from highly pathogenic H5N1 virus

Researchers at WashU Medicine have developed a nasal vaccine against the highly pathogenic H5N1 avian influenza virus, or bird flu, which has jumped from wild birds to livestock to humans.

30 Jan 2026

Sporadic Nipah virus cases highlight importance of global surveillance

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, is monitoring reports of a Nipah virus outbreak in India and emphasizes that such cases, while very concerning and serious, are not unexpected or unprecedented. Sporadic Nipah virus infections have occurred almost annually in parts of South Asia, particularly in India and Bangladesh, and do not indicate a new or escalating global threat.

30 Jan 2026

Dynamic viral markers predict treatment response in hepatitis B

The rate of functional cure (HBsAg loss) remains unsatisfactory following pegylated interferon (PEG-IFN) treatment in chronic hepatitis B. To optimize PEG-IFN administration, this study aimed to evaluate virological markers to predict functional cure and/or hepatitis B e antigen (HBeAg) loss.

30 Jan 2026

New diagnostic framework addresses challenges of rapidly-mutating RNA viruses

The rapid evolutionary dynamics of RNA viruses, driven by high mutation rates and the consequent formation of complex quasispecies populations, present a formidable obstacle to conventional molecular diagnostic approaches.

30 Jan 2026

Wastewater surveillance reveals hidden COVID spread beyond reported cases

As COVID-19 testing becomes less routine, official case numbers can make outbreaks look smaller than they really are.

30 Jan 2026

Sino Biological expands research reagent portfolio to support global Nipah virus vaccine and diagnostic development

Recent reports of Nipah virus (NiV) infections in West Bengal, India, have reignited global concern, prompting public health authorities to prioritize research into this high-mortality pathogen.

From Sino Biological Inc. 30 Jan 2026

Emerging animal viruses may pose overlooked threats to future human outbreaks

Two emerging pathogens with animal origins - influenza D virus and canine coronavirus - have so far been quietly flying under the radar, but researchers warn conditions are ripe for the viruses to spread more widely among humans.

29 Jan 2026

How DNA and life experiences leave distinct marks on the human immune system

Using single-cell epigenomic profiling of immune cells from 110 individuals, researchers show that genetic variation and environmental exposures shape the human immune system through distinct DNA methylation mechanisms. Genetic effects concentrate within gene bodies of memory cells, while environmental exposures primarily remodel regulatory regions in naive immune cells.

28 Jan 2026

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