ABCA1 and viral infectious disease: Given the importance of cholesterol to viral infection and the fact that 25HC is a metabolite of cholesterol, qRT-PCR analysis was applied to measure the mRNA levels of the indicated genes of cholesterol metabolism, including sterol regulatory element binding transcription factor 2 (SREBF2) for synthesis, ATP binding cassette subfamily A member 1 (ABCA1) for efflux, and acetyl-CoA acetyltransferase 1 (ACAT1), and acetyl-CoA acetyltransferase 2 (ACAT2) for esterification.