Host restriction factors that determine susceptibility for in vitro HIV-1 infection

The natural course of HIV-1 infection is widely varialbe with extremes of
disease progression within 2 years (rapid progressors) or continious
asymptomatic infection for more than 15 years (long term non progressors).
Moreover, certain people are relatively resistant to HIV-1 infection despite
high levels of sexual risk behavior (high risk seronegatives). In vitro, the
ability of HIV-1 to replicate on CD4+ T cells and macrophages also varies
considerably from donor to donor. In the majority of cases, the underlying
mechanism responsible for the variable outcome of exposure to HIV-1 is not
known.

The overall goal of our research is to identify host factors responsible for
the variability in HIV-1 susceptibility. We hypothesize that host factors that
either restrict or enable HIV-1 replication will be additional targets for
therapeutic intervention. The host factors involved might directly mediate or
interfere with HIV-1 replication or might influence activation levels and
immune response to the infection. We will focus on the following research
questions:

1. how much of the variation in in vitro HIV-1 susceptibility is explained by
known host gene polymorphisms?
2. which novel candidate host genes are correlated with in vitro HIV-1
susceptibility patterns?
3. which host genes explain in vitro and in vivo HIV-1 susceptibility?

We will collect blood samples from 600 healthy donors. CD4+ T cells and
macrophages will be isolated, cultured and subsequently infected with HIV-1.
For each donor, susceptibility to HIV-1 will be scored based on virus
production at day 14 after infection. Donors will be classified into groups of
high and low susceptibility based on the number of virus strains that can
replicate in their cells. Polymorphisms in host genes known to influence HIV-1
infection will be determined in the stored DNA samples (isolated from the same
blood samples) for the top 100 ("susceptible" group) and bottom 100
("resistant" group), using existing assays that have previously been used.
Donors whose susceptibility pattern can be explained by their genotype for
these known polymorphisms will be excluded from further analysis. To identify
additional host cell factors that may explain the susceptibility patterns in
the groups without known HIV-1 related polymorphisms, we will perform
genome-wide Single Nucleotide Polymorphism (SNP) genotyping of the remaining
individuals.

An additional ~14 ml of blood will be collected from each participant. Since
the venapunction will be performed at the blood bank, where the donors will
have to be for their regular blood donation, the burden to the participant will
be limited, or almost negligible. No specific or additional venapunction will
be required for our blood sample.