Strong Protection Elicited by an Immunodeficiency Virus Vaccine in Non-Human Primates

ATLANTA, GA--(Marketwired - Mar 7, 2016) - GeoVax Labs. Inc. (OTCQB: GOVX) today announced that the simian analogue of the company's human immunodeficiency virus (HIV) vaccine, GOVX-B11, provided a 76 percent reduction in per exposure risk of simian immunodeficiency virus (SIV) infection in young adult rhesus macaques. Per exposure risk was assessed over 12 weekly rectal exposures. The study, supported by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH), also showed the vaccine providing much better protection for young adult than middle-aged and older macaques.

The test vaccine used a DNA vaccine expressing non-infectious virus-like particles (VLPs) to prime the immune response and a modified vaccinia Ankara (MVA) vaccine, also expressing non-infectious VLPs, to boost the primed response. The vaccine regimen included two DNA primes at weeks 0 and 8 followed by two MVA boosts at weeks 16 and 32. The efficacy of the vaccine was tested at 6 months after the final MVA boost by 12 weekly rectal exposures to a pathogenic SIV given at a dose that infected approximately 30 percent of the unvaccinated animals at each challenge. Animals that were less than 10 years old (estimated human age of about 40) had much better protection than those over 10 years old. The age-dependence for protection was stronger than typically seen for vaccines and likely reflects the HIV target for protective antibody being particularly well-camouflaged.

The human version of the vaccine, GOVX-B11, has undergone clinical testing through the NIAID-supported HIV Vaccine Trials Network (HVTN) in Phase 1 and 2a trials involving about 500 individuals. These trials have shown the vaccine to have excellent safety and reproducible ability to elicit immune responses. Based on the results of the clinical trials, as well as the current preclinical trial, further evaluation of the GOVX-B11 vaccine in humans will use two DNA primes followed by three MVA boosts with the 16 week rest used in this trial between the last two MVA boosts.

"This trial showed strong protection in young adults for the simian version of our GOVX-B11 HIV vaccine," said GeoVax Chief Scientific Officer, Harriet L. Robinson, Ph.D. "We did not anticipate the extent of the age-dependence of protection, which suggests that people younger than 40 will respond better to HIV vaccines than older individuals. The most rapid increase in infections in the United States is in 13 to 24 year olds, an age range that should respond very well to the vaccine. In this age group, infections increased at a rate of 10.5% per year between 2002 and 2011. This study furthers our resolve to advance GOVX-B11 in human clinical trials."

The study was a collaborative effort between the NIAID's Simian Vaccine Evaluation Unit (SVEU) which conducted the study, and the Yerkes National Primate Research Center where assays for antibody and T cell responses were conducted.

About GeoVax

GeoVax Labs, Inc. is a clinical-stage biotechnology company developing human vaccines against infectious diseases using its Modified Vaccinia Virus Ankara-Virus Like Particle (MVA-VLP) vaccine platform. The Company's most advanced development programs are focused on vaccines against HIV and hemorrhagic fever viruses (Ebola, Marburg and Lassa). Recently these efforts have been extended to Zika virus. GeoVax's vaccine platform supports production of non-infectious VLPs in the person receiving the vaccine. The production of VLPs in the person being vaccinated mimics a natural infection, stimulating both the humoral and cellular arms of the immune system to recognize, prevent, and control the target infection should it appear. GeoVax also recently began a program to evaluate the use of its MVA-VLP platform in cancer immunotherapy.

About Yerkes National Primate Research Center

For eight decades, the Yerkes National Primate Research Center, Emory University, has been dedicated to conducting essential basic science and translational research to advance scientific understanding and to improve the health and well-being of humans and nonhuman primates. Today, the center, as one of only eight National Institutes of Health-funded national primate research centers, provides leadership, training and resources to foster scientific creativity, collaboration and discoveries. Yerkes-based research is grounded in scientific integrity, expert knowledge, respect for colleagues, an open exchange of ideas and compassionate quality animal care.

Within the fields of microbiology and immunology, neurologic diseases, neuropharmacology, behavioral, cognitive and developmental neuroscience, and psychiatric disorders, the center's research programs are seeking ways to: develop vaccines for infectious and noninfectious diseases; understand the basic neurobiology and genetics of social behavior and develop new treatment strategies for improving social functioning in ASD and schizophrenia; interpret brain activity through imaging; increase understanding of progressive illnesses such as Alzheimer's and Parkinson's diseases; unlock the secrets of memory; treat drug addiction; determine how the interaction between genetics and society shape who we are; and advance knowledge about the evolutionary links between biology and behavior.

Journal Reference:

1. Strong, but Age-Dependent, Protection Elicited by a DNA/Modified Vaccinia Ankara Simian Immunodeficiency Virus Vaccine. Venkateswarlu Chamcha, Sunil Kannanganat, Sailaja Gangadhara, Rafik Nabi, Pamela A. Kozlowski, David C. Montefiori, Celia C. LaBranche, Jens Wrammert, Brandon F. Keele, Harikrishnan Balachandran, Sujata Sahu, Michelle Lifton, Sampa Santra, Rahul Basu, Bernard Moss, Harriet L. Robinson, Rama Rao Amara. Open Forum Infect Dis (2016) doi: 10.1093/ofid/ofw034 First published online: February 11, 2016

Forward-Looking Statements
Certain statements in this document are "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act. These statements are based on management's current expectations and are subject to uncertainty and changes in circumstances. Actual results may differ materially from those included in these statements due to a variety of factors, including whether: GeoVax can develop and manufacture its vaccines with the desired characteristics in a timely manner, GeoVax's vaccines will be safe for human use, GeoVax's vaccines will effectively prevent targeted infections in humans, vaccines will receive regulatory approvals necessary to be licensed and marketed, GeoVax raises required capital to complete vaccine development, there is development of competitive products that may be more effective or easier to use than GeoVax's products, GeoVax will be able to enter into favorable manufacturing and distribution agreements, and other factors, over which GeoVax has no control. GeoVax assumes no obligation to update these forward-looking statements, and does not intend to do so. More information about these factors is contained in GeoVax's filings with the Securities and Exchange Commission including those set forth at "Risk Factors" in GeoVax's Form 10-K.