Portal de Periódicos da CAPES

Family Orthomyxoviridae

2017; Multidisciplinary Digital Publishing Institute; Linguagem: Inglês

10.1016/b978-0-12-803109-4.00023-4

1999-4915

Susan Payne,

Virology and Viral Diseases

The family Orthomyxoviridae contains significant pathogens of humans and animals. Virions are spherical to filamentous, about 100 nm in diameter. Genomes are segmented, single-stranded negative-strand RNA. Influenza A virus infects a wide variety of mammals and birds, replicating in the respiratory and/or gastrointestinal tracts. But in birds, highly pathogenic avian influenza viruses (HPAIV) cause severe systemic infections. Transmission of HPAIV to humans is rare, but can result in severe disease with high mortality. Influenza A virus is genetically diverse, a consequence of accumulating and tolerating point mutations, a process called antigenic drift. Influenza viruses can also reassort their segmented genomes to generate novel viruses with altered host range and virulence, a process called antigenic shift. In the early 20th century (1918–19) a particularly lethal strain of influenza A virus infected approximately one-third of the world's population and caused an estimated 40 million deaths. Although a pandemic of that magnitude has not occurred since, influenza viruses are continuously monitored. In humans, influenza is a mild to severe respiratory tract disease characterized by rapid onset of fever, muscle aches, and fatigue. Severe disease can result from primary viral pneumonia or secondary bacterial infections. Vaccines are manufactured on a yearly cycle to account for the processes of antigenic drift and shift. The ability to manufacture the correct vaccines depends on a robust global tracking system.