What is budding virus?

Budding, in virology, is a process by which new virions are released from the plasma membrane of an infected cell. The virus assembles new viral particles just beneath the cell’s plasma membrane, with the membrane itself serving as the viral envelope. As virus particles accumulate, they protrude from the cell surface, eventually pinching off and being released into the extracellular environment.

When a virus buds from a cell, the host cell membrane fuses with the virus's envelope, and the virus is released. This process is different from other methods of viral release, such as lysis, where the host cell is destroyed to release the virus.

- Budding requires the interaction of the viral envelope with the host cell membrane. The viral envelope is composed of a lipid bilayer derived from the host cell membrane and contains viral proteins, such as glycoproteins, that are important in the budding process.

- Enveloped viruses are the ones that acquire an outer membrane during budding. Examples include HIV, hepatitis B virus, influenza virus, measles virus, and herpes simplex virus. Non-enveloped viruses, such as adenoviruses, poxviruses, and papillomaviruses, are released by cell lysis.

- The budding process involves several steps:

1) Assembly: The viral proteins and nucleic acids are assembled at the host cell membrane, forming immature virions.

2) Budding: The immature virions acquire the viral envelope by budding through the cell membrane.

3) Release: The mature virions are released from the cell by pinching off the budded structure.

The exact mechanism of budding can vary among different viruses, but the general steps outlined above are common to many enveloped viruses. Understanding the process of budding is important in the development of antiviral therapies and vaccines, as it provides potential targets for preventing the release of infectious virus particles from infected cells.