RNA thermometers (RNATs) regulate gene expression in response to temperature, allowing pathogens such as Neisseria meningitidis to switch on silent genes[clarification needed] after entering the host organism.

However the temperature for expression of Neisseria virulence-associated traits is 42 °C while other bacterial pathogen RNATs require 37 °C.

This is probably because N. meningitidis is an obligate commensal of the human nasopharynx and becomes pathogenic during inflammation due to viral infection.

Three independent RNA thermosensors were identified in the 5′UTRs of genes needed for: capsule biosynthesis (cssA), the expression of factor H binding protein (fHbp) and sialylation of lipopolysaccharide, which is essential for bacterial resistance against immune killing (lst).

Further study of molecular mechanisms of CssA RNAT showed that it acts as a rheostat that responds to small temperature changes around 37 °C which occur within the upper airways during infection.