12. What is the window phase
of an infection? How is this
concept important for the test
of HIV infection in blood
banks?

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The primary immune response the
body facing any is not
immediate. The phase is the
period the infection until the
of detectable specific
antibodies the infective agent.
In period, immunochemical tests
that search infections, like the
and the Western-blot for ,
give a negative result if the person
is infected by the agent. the
case of HIV, window phase can last
2 weeks to 3 .

The window phase is big problem for
blood that perform only
immunochemical on the donated
blood. is the reason why some
countries the blood are
submitted to a of questions
regarding their behavior, mainly
sexual and use related, in the
preceding the donation and
to voluntary confidential self ,
in which they declare their
blood may be or should be
excluded. of facing this
dangerous , modern blood
banks nowadays the PCR
(polymerase chain ) for HIV, a
test is not distorted by window
phase since it not antibody-based.
Using specific , the PCR detects
the of DNA generated by
transcription of the HIV .