What term refers to the lessening of virulence in a microorganism?

The term that refers to the lessening of virulence in a microorganism is attenuation. This process involves reducing or eliminating the pathogenicity of a microbe, making it less capable of causing disease. Attenuation is essential in the development of vaccines, where a weakened form of the pathogen is used to stimulate the immune system without causing disease, enabling the body to build immunity.

Understanding attenuation is crucial in microbiology and immunology, as it lays the groundwork for effective vaccine development and contributes to our knowledge of how pathogens can be manipulated to provide protection against diseases.