The
quick explanation:
HIV seroconversion is the point at which
antibodies to the
virus become detectable in an infected person's
blood. This could be anything from a few weeks to, very rarely, a year after initial infection. During this
window period the person will not test positive, since current tests look for the antibodies not the virus itself.
(Thanks to the Aids Coalition of Nova Scotia's "Aids 101" pages for this info).