Viruses, microscopic agents that can infect all forms of life, require a standardized naming system for effective global communication. Without a universal approach, the study and management of viral diseases would become disorganized and less effective.
The Global Naming Authority
The International Committee on Taxonomy of Viruses (ICTV) is the globally recognized body tasked with standardizing virus classification and nomenclature. This committee develops and maintains a universal taxonomic scheme for viruses, ensuring consistency in virology research and public health efforts.
The ICTV serves as the official reference point for virus taxonomy. Its work, such as identifying new taxa and defining species boundaries, is often performed by study groups. Anyone can submit proposals for new names or taxonomic changes, which are then considered by the ICTV’s Executive Committee.
Principles of Virus Classification
The ICTV classifies viruses using a hierarchical structure, similar to the classification system for other biological organisms. This system includes ranks such as realm, kingdom, phylum, class, order, family, subfamily, genus, and species. Viruses are assigned to these ranks based on characteristics like their genetic material (DNA or RNA), the structure of their nucleic acid (single-stranded or double-stranded), the presence or absence of an outer envelope, and their overall morphology.
The primary principle guiding virus classification is evolutionary relatedness, meaning that viruses should be grouped together based on their shared evolutionary history. While phenotypic and ecological properties, such as host range or replication strategy, can inform classification, they do not override evolutionary relationships. For instance, a virus’s ability to infect specific organisms or cell types, like the human immunodeficiency virus targeting CD4+ T cells, helps in its placement. Scientific names for viruses can be derived from various sources, including the disease they cause, the location of their discovery, or unique features of the virus itself.
Virus Names Versus Disease Names
A common area of confusion involves the distinction between the name of a virus and the name of the disease it causes. The International Committee on Taxonomy of Viruses (ICTV) is responsible for naming viruses based on their genetic structure to aid in the development of diagnostic tests, vaccines, and medicines. In contrast, the World Health Organization (WHO) typically names the diseases, focusing on public health communication, prevention, and treatment.
For example, the virus that caused the 2003 SARS outbreak is called Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV), while the disease is Severe Acute Respiratory Syndrome. More recently, the virus responsible for the 2019 pandemic was named Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) by the ICTV. The WHO then named the disease it causes COVID-19, which stands for “Coronavirus Disease 2019”. This separation helps avoid confusion and ensures that disease names are not stigmatizing, following WHO guidelines that discourage naming diseases after geographic locations, people, or animals.
Naming New Viral Variants
When new variants or strains of existing viruses emerge, specific processes are followed for their naming. The World Health Organization (WHO) plays a significant role in assigning simplified, non-stigmatizing names for public communication. For instance, with SARS-CoV-2, the WHO introduced the use of Greek letters (e.g., Alpha, Beta, Delta, Omicron) for “variants of concern” and “variants of interest” to make them easier for non-scientific audiences to discuss.
While the public often uses these simpler names, scientific communities continue to use more detailed lineage names, such as B.1.1.7 for Alpha or B.1.351 for Beta, which convey specific genetic information for research and tracking. The WHO’s criteria for designating a new variant as a “variant of concern” include increased transmissibility, more severe disease, reduced immune response from previous infection or vaccination, decreased treatment effectiveness, or reduced diagnostic detection. This dual naming system supports both scientific precision and clear public health messaging.