Glossary

tropism – the type of coreceptor used by HIV in order to attach to and then infect a cell. If HIV uses the CCR5 coreceptor on the surface of the a CD4 cell it is called R5-tropic. If it uses the CXCR4 co receptor it is called R4-tropic). Early HIV infection is usually R5-tropic but over time, especially in late disease (if CD4 counts drop to less than 50 cells/mm3) the virus shifts to being X4-tropic.  Mixed tropic refers to a having some viruses that use R5 and some that use X4.

fold-change – a term relating to drug resistance after a phenotype resistance test.

4-fold resistance (also called a 4-fold loss in sensitivity) means you need to use four times the dose to get the same reduction in viral load.

free radical – a chemical produced after a molecular reaction, often containing oxygen, that has one ‘free’ unpaired electron on its outer surface. This makes it able to react and damage other cells, and perhaps increase progression of cardiovascular disease, cancers and aging. See antioxidant.

MSM – men who have sex with men.

sanctuary site – see compartment site.