#13,905 One of the remarkable, and most worrying, things about influenza is its ability to continually re-in…
One of the remarkable, and most worrying, things about influenza is its ability to continually re-invent itself, either via a slow process of antigenic drift, or rapidly through antigenic shift (reassortment).
- Antigenic drift causes small, incremental changes in the virus over time. Drift is the standard evolutionary process of influenza viruses, and often come about due to replication errors that are common with single-strand RNA viruses (see NIAID Video: Antigenic Drift).
- Shift occurs when one virus swap out chunks of their genetic code with gene segments from another virus. This is known as reassortment. While far less common than drift, shift can produce abrupt, dramatic, and sometimes pandemic inducing changes to the virus (see NIAID Video: How Influenza Pandemics Occur).
While reassortment can occur with just about any influenza A virus, H5Nx subtypes appear unusually agile in this department, and genetic contributions from LPAI H9N2 can be found inside many avian viruses (see PNAS: Reassortment Potential Of Avian H9N2).