Viruses come in a bewildering array of shapes and sizes with genomes that can be DNA or RNA, single-stranded or double-stranded, and that sometimes change their forms during replication. Although individual particles are tiny, viruses collectively are the most abundant life forms on earth, with an estimated 1031 total infectious units globally at any given time.
Virology is a critically important National Research Priority because our natural history has been profoundly shaped by viruses. Poliovirus infected and paralyzed the ancient Egyptians and resists eradication to this day. The variola virus (smallpox) introduced by colonizing Europeans killed up to 95% of the indigenous population of the Americas, and in the 20th century alone killed as many as 500 million people. The 1918 influenza epidemic killed 100 million people. Approximately 15% of all human cancers are caused by viruses. Millions of people are living with persistent infections of hepatitis B virus (HBV, ~350 million), hepatitis C virus (HCV; ~150 million) or the human immunodeficiency virus (HIV; ~40 million), and nearly every human on earth is infected with at least one herpesvirus. Most recently, the emergence of SARS-CoV-2 and its variants caused the COVID-19 pandemic that we have all experienced and that has infected ~450 million people, killing ~6 million (March 2022 statistics). Unfortunately, human expansion into new ecological niches combined with facile and rapid global travel sets the stage for the emergence of additional, new pandemics.
Human, animal and plant viral infections have massive global health and economic impacts, but it’s not all bad news. Virology research has generated fantastic success stories, from the eradication of smallpox through vaccination, to the cure of persistent HCV with antiviral drugs, and most recently the rapid development and deployment of multiple, successful SARS-CoV-2 vaccines, drugs, and immunotherapies. Moreover, basic research into the molecular mechanisms of viral replication, immune evasion and pathogenesis continues to highlight opportunities for novel preventions and treatment.
Virology work is at the heart of much of today’s knowledge of general molecular and cellular biology, immunology, and oncology. Oncogenes were discovered as gene fragments pirated by retroviruses. The biology of tumor suppressors was revealed through their inhibition by viral proteins. The study of HIV/AIDS expanded our understanding of the human adaptive immune system. Genome editing uses CRISPR technology that actually functions as a bacterial adaptive immune response against bacteriophage (viruses that infect bacteria).
Virology is where gene splicing was first identified, and where the revelation of reverse transcription (here at UW-Madison) overturned the “central dogma” of genetic information transfer, winning a Nobel Prize for Howard Temin. Countless other advances in cell and molecular biology have been made through the study of viruses. For these reasons and more, basic and clinical virology research is now and will continue to be a significant contributor to human health and knowledge.