What is original antigenic sin in influenza?

The “original antigenic sin” (OAS) concept refers to the impact of the first influenza virus variant encounter on lifelong immunity. Although this model has been challenged since its discovery, past exposure, and likely one’s first exposure, clearly affects the epitopes targeted in subsequent responses.

How does the immune system respond to influenza A?

Following influenza infection or receipt of a flu vaccine, the body’s immune system develops antibodies that recognize and bind to “antigenic sites,” which are regions found on an influenza virus’ surface proteins.

Which infectious disease is the best example of original antigenic sin?

The preferential expansion of cross-reactive antibodies, or T-lymphocytes for that matter, by a related antigen has been termed the original antigenic sin and was first described by Thomas Francis Jr. in 1960. The phenomenon was initially described for influenza virus, but also has been found for dengue and rotavirus.

What is TH1 and TH2 immune response?

Definition. TH1 immune response refers to the cytokine-mediated immune response generated by TH1 cells against intracellular parasites such as bacteria and virus, while TH2 immune response refers to the cytokine-mediated immune response generated by TH2 cells against large, extracellular parasites such as helminths.

What is antigenic shift and antigenic drift in influenza?

Influenza strains are constantly mutating. A small change to the genetic makeup of influenza strains is referred to as antigenic drift, while a major change is called antigenic shift.

What is the host response to influenza virus?

Influenza A viruses (IAVs) are contagious pathogens responsible for severe respiratory infection in humans and animals worldwide. Upon detection of IAV infection, host immune system aims to defend against and clear the viral infection.