Hemagglutinin is a protein found on the surface of the influenza virus. It is responsible for binding the virus to the host cell, initiating the infection process. Hemagglutinin is a target for the immune system, and antibodies against it can prevent infection.

The flu NA (neuraminidase) protein is crucial because it plays a key role in the influenza virus's ability to infect host cells and spread within the body. It helps the virus to release newly formed viral particles from infected cells, facilitating the spread of the infection. As such, it's a key target for antiviral drugs and vaccine development, helping in controlling and preventing flu outbreaks.

This post provides a detailed exploration of the CR9114 antibody, focusing on its binding properties and effectiveness against various influenza A virus strains. It covers the specific gene segments from which CR9114 is derived, explaining its broad reactivity to both group 1 and group 2 influenza A viruses. The article highlights the significance of the HA stem region in the virus and how CR9114's binding to this region blocks the necessary conformational changes for viral entry into host cells. Additionally, it compares CR9114 to other antibodies like CR6261 and FI6v3, discussing their different binding modes and effectiveness. The content is technical and geared towards readers with a background in biology and immunology.