|EMBARGOED FOR RELEASE
Wednesday, Dec. 11, 1996
2:00 PM Eastern Time
Fauci: New Findings on Host Factors Illuminate AIDS
- how the normal signalling molecules of a person's
immune system (cytokines) regulate the level at which
HIV replicates in the body, thereby influencing the rate
of HIV disease progression. Some of these cytokines
induce HIV replication and some of them suppress the
virus; tipping the balance between these positive and
negative forces can result in dramatic increases or
decreases in HIV replication.
- how the activation of the immune system, by HIV itself
as well as by other pathogens, allows HIV to replicate
- how different strains of HIV use recently discovered cell
surface molecules, in addition to the well-known CD4 molecule,
to bind to and enter their target cells. Intriguingly, these co-receptors
are shared by the virus and certain of the body's own cytokines.
Researchers speculate that certain cytokines suppress HIV
infection by competitively occupying or downregulating the
common receptor they share with HIV. Investigators now are
exploring the feasibility of therapeutic strategies that might
block these receptors with peptides, antibodies or pharmacologic
- new insights into the "tropism" or preference of different HIV
strains for certain cells. Strains of HIV that infect macrophages
and T cells are the main ones found in an HIV-infected person
early in the course of disease; as time progresses, strains that
replicate efficiently in T cells but not in macrophages appear,
coincident with the decline of the immune system. This transition
may be explained in part by the changing cytokine profiles and
expression of co-receptors on cells in an HIV-infected person's
- how mutations in the human genes for HIV co-receptors may
help explain why some individuals do not become infected with
HIV despite repeated exposure, and why individuals who are
HIV-infected may have very different rates of disease progression.
NIAID is a component of the National Institutes of Health (NIH).
NIAID conducts and supports research to prevent, diagnose
and treat illnesses such as HIV disease and other sexually
transmitted diseases, tuberculosis, asthma and allergies. NIH
is an agency of the Public Health Service, U.S. Department of
Health and Human Services.