Based in Atlanta, GeoVax Labs, Inc. is a biotechnology company developing human vaccines for diseases caused by HIV and other infectious agents. Now the company has decided to expand its preventative HIV/AIDS vaccine development effort in collaboration with the National Institute of Allergy and Infectious Diseases (NIAID), part of the U.S. National Institutes of Health (NIH) and the HIV Vaccine Trials Network (HVTN).

The HVTN plans to clinically test a novel vaccine product developed by GeoVax scientists that expresses human granulocyte-macrophage colony stimulating factor (GM-CSF) in combination with inactivated HIV proteins. The novel vaccine consists of a recombinant DNA vaccine co-expressing human GM-CSF and non-infectious HIV viruslike particles. The DNA vaccine is used to prime immune responses that are subsequently boosted by vaccination with a recombinant modified vaccinia Ankara (MVA) vectored vaccine. The MVA expresses the HIV viruslike particles, but does not express GM-CSF. The regimen builds on the GeoVax DNA/MVA vaccine that is currently in Phase 2a clinical testing through the HVTN.

GM-CSF is a cytokine (growth stimulating protein) that serves to expand and mature cells that initiate immune responses and has undergone extensive testing in humans for cancer vaccines. The GM-CSF-adjuvanted vaccine was added to GeoVax's portfolio because of the outstanding ability of the simian prototype vaccine to induce immune responses that prevented simian immunodeficiency virus (SIV) infection. In nonhuman primates, the GM-CSF-enhanced vaccine achieved protection against SIV in 70% of the animals. Protection was measured against 12 weekly rectal challenges using a dose of SIV that is estimated to be 30 to 300 times higher than the typical exposure dose of HIV in mucosal transmission in humans.

"For years, the HIV vaccine field has been working with vaccines that elicited immune responses that primarily controlled immunodeficiency virus challenges in infected animals, but did not actually prevent infections," said Dr. Harriet Robinson, Chief Scientific Officer at GeoVax. "The ultimate goal is to prevent infections. The co-expression of GM-CSF with the SIV proteins is a vaccine design that appears to be a large step toward reaching this goal. In our trials in nonhuman primates, GM-CSF enhanced the quality of the SIV-specific antibody response. Antibody is present in blood and tissues and has the potential of blocking SIV before it infects cells. The GM-CSF-adjuvanted vaccine induced the production of antibodies characterized with increased tightness of antibody binding. The tightness of antibody binding, known as avidity, can be expressed as an index. Animals with indices above 40 were protected from infection, whereas animals with lower indices were infected with the number of challenges to infection correlating with their index."

"We are very pleased that the HVTN will be conducting trial HVTN 094 of our GM-CSF adjuvanted vaccine product, which we expect will begin late this year," said Dr. Robert McNally, CEO of GeoVax. "The HVTN, funded by the NIAID, is the largest worldwide clinical trials network dedicated to the development and testing of HIV/AIDS vaccines. We are looking forward to working with an excellent team of HVTN trial investigators."

GeoVax Labs, Inc.