CCR5 inhibitors are a new class of antiretroviral drug used in
the treatment of HIV. They are designed to prevent HIV infection of
CD4 T-cells by blocking the CCR5 receptor. When the CCR5 receptor
is unavailable, 'R5-tropic' HIV (the variant of the virus that is
common in earlier HIV infection) cannot engage with a CD4 T-cell to
infect the cell. Maraviroc, the first drug from this class to be
marketed (as Selzentry in the US, Celsentri in Europe), was
licensed in the summer of 2007. Drugs in this class exploit the
knowledge gained when trying to understand why a small minority of
people of northern European descent had a degree of naturally
occurring immunity against HIV. It was discovered that a harmless
genetic mutation meant that their CCR5 receptors were blocked
(which some have speculated must have developed as a defence
against the plague epidemics) thus denying HIV of its usual means
of gaining a foothold.
