Biology Reference
In-Depth Information
F i g u r e 17.3. CEM cells were ®xed and permeabilized and then stained with 100 ng of murine
IgG1, an isotype and subtype control (closed histograms) or with 100 ng of murine anti-bcl-2 mono-
clonal antibody (open histograms). The stained cells were processed by standard ampli®cation tech-
niques (left panel ) or by EAS (right panel ). The mean channel numbers of the histograms are
shown.
Recognition of Viral Gene Products
HIV-1 produces many di¨erent proteins: gp120 Env, gp41 Env, p17 Gag, p9
Gag, p24 Gag, p11 Pol (protease), p66/p51 Pol (reverse transcriptase), p31 Pol
(integrase), Nef, Vif, Vpr, Vpu, Tat, and Rev. Moreover, these proteins are
produced and expressed in infected cells according to a viral program that re-
lates to the life cycle of the virus and consequently to the pathogenesis of the
infection. Many of these proteins are regulatory and are not produced in large
amounts. The expression of structural proteins is also interesting because their
production signi®es viral production. It is important to assess low-level viral
production, particularly in the setting of antiviral therapies. Also, gp120 is a
membrane protein expressed on the cell surface and thus it represents a tag for
an infected cell. It is likely that the enhanced ¯uorescent signal that can be ob-
tained with EAS for both cell surface molecules and intracellular molecules can
be used to assess viral protein production in HIV-1 infected cells.
In several studies, investigators have suggested the possibility that HIV-1 can
exist as a latent infection ( Borvak et al., 1995; Chun et al., 1997; Emiliano et
al., 1996; Finzi et al., 1999). Latency at a cellular level has been proposed to
account for an organismal phenomenon: the recrudescence of viral particles in
the serum after successful antiviral therapy. But the possibility of latency of the
virus in the organism has not been translated in terms of a latent cellular in-
fection such as exists for herpes virus infections. Does HIV-1 exist as a latent
cellular infection? If so, which viral proteins are produced in this form of
