HIV proliferates within the human immune
system. The virus consists
of an outer envelope with docking sites, an inner core containing the genetic information for replication
of the virus, and enzymes that regulate this replication. HIV destroys certain white blood cells known
as T helper cells or CD4
cells.
The human immune system generally manages to keep HIV in check
for years. This means that although the virus is present in the body, the affected person has no symptoms
and does not appear to be ill. At this stage the person is said to be HIV-infected, or HIV-positive.
