Natural killer cells in antiviral immunity

This Review covers the role of natural killer cells in acute and chronic viral infections, with emphasis on human infections and insights from patients with primary immunodeficiencies affecting natural killer cells. It also describes the emerging data on how natural killer cells are involved in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Natural killer (NK) cells play an important role in innate immune responses to viral infections. Here, we review recent insights into the role of NK cells in viral infections, with particular emphasis on human studies. We first discuss NK cells in the context of acute viral infections, with flavivirus and influenza virus infections as examples. Questions related to activation of NK cells, homing to infected tissues and the role of tissue-resident NK cells in acute viral infections are also addressed. Next, we discuss NK cells in the context of chronic viral infections with hepatitis C virus and HIV-1. Also covered is the role of adaptive-like NK cell expansions as well as the appearance of CD56(-) NK cells in the course of chronic infection. Specific emphasis is then placed in viral infections in patients with primary immunodeficiencies affecting NK cells. Not least, studies in this area have revealed an important role for NK cells in controlling several herpesvirus infections. Finally, we address new data with respect to the activation of NK cells and NK cell function in humans infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) giving rise to coronavirus disease 2019 (COVID-19).

Automated summary

This review explores the role of natural killer cells in acute and chronic viral infections, particularly focusing on insights from patients with primary immunodeficiencies. It also discusses the involvement of natural killer cells in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The review highlights the importance of NK cells in innate immune responses to viral infections and provides recent insights into their role in human studies.