Argos Therapeutics Publishes Research on the Immunosuppressive Properties of HIV

-Manuscript Published in PLoS One Relevant to Development and Evaluation of HIV
Immunotherapies-
DURHAM, N.C.--(Business Wire)--
Argos Therapeutics today announced the publication of an article related to its
Arcelis HIV immunotherapy program in the peer-reviewed online journal PLoS ONE.
The publication details research on the progression of HIV infection, virulence
factors, the immunosuppressive properties of HIV, and how this research may
influence the development of HIV immunotherapies.

The manuscript, titled "The Immunosuppressive Properties of the HIV Vpr protein
are Linked to a Single Highly Conserved Residue, R90," details the study of
IL-12 suppression by the HIV viral protein R (Vpr) in monocyte-derived dendritic
cells (DC). IL-12 is a critical cytokine, required for effective immune
responses, that is secreted by macrophages, monocytes and dendritic cells, and
is suppressed by Vpr, implicating Vpr as an important virulence factor in HIV
infection. Researchers hypothesized that the Vpr protein may be required to
establish productive HIV infection, because it disables antigen presenting cells
of the first infected mucosal tissues.

Analysis revealed that some previously reported C terminal Vpr mutations do not
alleviate the block of IL-12 secretion; however, a novel single conservative
amino acid substitution, R90K, completely reverses the suppression. Further
analysis demonstrated that R90 may not directly regulate the IL-12 pathway, but
instead alleviates the suppressive effect through lowering Vpr intracellular
levels. As a result, this study supports Vpr as an HIV virulence factor during
HIV infection, and for the first time, provides a link between evolutionary
conservation of Vpr and its ability to suppress IL-12 secretion by DCs.

Charles Nicolette, Ph.D., Chief Scientific Officer and Vice President of
Research and Development of Argos Therapeutics, said: "Our research suggests a
natural selection for sequences that suppress IL-12 secretion by dendritic cells
and against mutations that relieve this suppression. Dendritic cells activated
in the presence of Vpr are defective in their production of IL-12, which
contributes to the progression of HIV infection. Argos` research into the
immunobiology of HIV is providing important information to support those
developing and evaluating HIV immunotherapies, including our own based on our
Arcelis personalized immunotherapy platform."

The manuscript was authored by: Irina Tcherepanova, Aijing Starr, Melissa Adams,
Brad Lackford, David Calderhead, Don Healey, Mohamed-Rachid Boulassel,
Jean-Pierre Routy and Charles Nicolette.

The development of Argos` Arcelis HIV immunotherapy program is part of the
Company`s broad collaboration with Kyowa Hakko Kirin Co., Ltd.

About Argos Therapeutics, Inc.

Argos is an immunotherapy company developing new treatments for cancer,
infectious and autoimmune diseases, and transplantation rejection. The Company
has generated multiple platform technologies and a diverse pipeline of products
based on its expertise in the biology of dendritic cells - the master switch
that turns the immune system on or off. www.argostherapeutics.com

MacDougall Biomedical Communications
Jennifer Conrad, 781-235-3060
or
Argos Therapeutics
Jeff Abbey, 919-287-6308

Copyright Business Wire 2009