The chemical reactions and pathways resulting in the breakdown of cholesterol, cholest-5-en-3 beta-ol, the principal sterol of vertebrates and the precursor of many steroids, including bile acids and steroid hormones.

A fatty acid beta-oxidation pathway in which the initial step of each oxidation cycle, which converts an acyl-CoA to a trans-2-enoyl-CoA, is catalyzed by acyl-CoA dehydrogenase; the electrons removed by oxidation pass through the respiratory chain to oxygen and leave H2O as the product. Fatty acid beta-oxidation begins with the addition of coenzyme A to a fatty acid, and ends when only two or three carbons remain (as acetyl-CoA or propionyl-CoA respectively).

The increase in size or mass of an organism, occurring within the cells or tissues of the host organism. This may (but not necessarily) include a filamentous growth form, and also can include secretion of proteases and lipases to break down host tissue. The host is defined as the larger of the organisms involved in a symbiotic interaction.