What is an influenza virus?

What is an influenza virus?

What is an influenza virus?

Virus introduction
Influenza virus, a representative species of Orthomyxoviridae, referred to as influenza virus, including human influenza virus and animal influenza virus, human influenza virus is divided into A (A), B (B), C ( C) Type III is the causative agent of influenza (flu). Among them, the antigenicity of influenza A virus is prone to mutation, causing a worldwide pandemic many times. For example, in the 1918-1919 pandemic, at least 20 million to 40 million people worldwide died of influenza; influenza B virus is also more pathogenic to humans, but people have not found that influenza B virus has caused worldwide A pandemic; influenza C virus causes only insignificant or mild upper respiratory tract infections in humans and rarely causes epidemics. Influenza A virus was successfully isolated in 1933, influenza B virus was acquired in 1940, and influenza C virus was not successfully separated until 1949.
Influenza classification



According to the target of influenza virus infection, the virus can be divided into human influenza virus, swine influenza virus, equine influenza virus and avian influenza virus. The human influenza virus can be divided into three categories according to the antigenicity of its nuclear protein:
Influenza A virus, also known as influenza A virus
Influenza B virus, also known as influenza B virus
Influenza C virus, also known as influenza C virus
Influenza viruses that infect other animals such as birds and pigs have the same antigenicity as the human influenza A virus, but since the classification of influenza A, B and C viruses is only for human influenza viruses, it is usually not An influenza virus other than a human host such as avian influenza virus is referred to as an influenza A virus.
Based on the antigenicity of nuclear proteins, influenza viruses are also classified into different subtypes based on the antigenicity of hemagglutinin HA and neuraminidase NA.