ATLANTA, GA--(Marketwired - Nov 7, 2017) -  GeoVax Labs, Inc. (OTCQB: GOVX), a biotechnology company developing human vaccines, today announced publication of its manuscript entitled "A Zika Vaccine Targeting NS1 Protein Protects Immunocompetent Adult Mice in a Lethal Challenge Model." The paper is published today in the peer-reviewed open access journal Scientific Reports by Nature Research, and can be viewed at www.nature.com/articles/s41598-017-15039-8.

The paper published today reports research showing that a single intramuscular dose of GeoVax's Zika vaccine (GEO-ZM02) provided 100% protection in normal mice challenged with a lethal dose of Zika virus (ZIKV) delivered directly into the brain. This is i) the only Zika vaccine in development which is based solely on the ZIKV NS1 protein, and ii) the first report of single-dose vaccine that afforded full protection against ZIKV using an immunocompetent lethal mouse challenge model.

The vaccine was tested at the Division of Vector-Borne Diseases, Centers for Disease Control and Prevention (CDC) in Fort Collins, Colorado with funding from the CDC. In the study, outbred immunocompetent mice were exposed to a lethal challenge dose of ZIKV delivered directly into the brain. A single dose of GeoVax's ZIKV NS1 vaccine protected 100% of vaccinated animals. In contrast, 80-90% of sham-immunized control animals died within ~7 days.

GeoVax selected the ZIKV NS1 antigen as the target immunogen for its vaccine, as recent findings in mice and non-human primates indicate a potential risk of more severe clinical sequelae of subsequent dengue virus infection following traditional vaccination approaches based on the ZIKV envelope proteins. This "Antibody Dependent Enhancement (ADE) of infection" phenomena, previously shown to enhance dengue infections in humans⁽¹⁾, is now expected to potentially include ZIKV, dengue virus' closest relative⁽²⁾. Results of a new study performed in Rhesus Macaques provides in vivo evidence that prior exposure to ZIKV infection can enhance dengue infections⁽³⁾ should the individual be subsequently infected by a dengue infected mosquito. An NS1-based vaccine avoids the theoretical ADE risk since this protein is not a surface protein on the virus. This approach holds the promise for a highly effective Zika vaccine that is inherently safer than enveloped-based vaccines for those who live in areas where the Zika virus co-circulates with other flaviviruses such as dengue.

(1) Halstead S. B., Pathogenesis of dengue: challenges to molecular biology. Science 239, 476-481 (1988)
(2) Barba-Spaeth G. et al., Nature 2016 Jun 23. Dejnirattisai W. et al., Nat Immunol 2016 Jun 23
(3) George et al, Scientific Reports 7, Article number: 10498, 2017

Farshad Guirakhoo, PhD, GeoVax's Chief Scientific Officer, commented, "Currently, no approved vaccine or therapeutic medicine exists for the prevention or treatment of infection from the ZIKV. Our MVA (Modified Vaccinia Ankara) platform is used to express NS1, a protein abundantly produced by ZIKV, which is a target for both antibody and T cell mediated immunity. The MVA-NS1 vaccine induces both humoral and cellular immunity and uniquely has protected mice from intracranial challenge with ZIKV. We believe our vaccine potentially offers the best solution to safely protect at-risk populations from the Zika epidemic. GEO-ZM02 not only has the potential of a single-dose vaccine, which is practical to combat epidemics in resource-strained countries, but also does not bear the risk of enhancing other flavivirus infections, such as dengue virus, in vaccinated subjects."

Dr. Guirakhoo continued, "GEO-ZM02 uses GeoVax's proven MVA vaccine platform that has been shown to be safe and to induce durable antibody and T-cell responses in multiple human clinical trials for GeoVax's prophylactic HIV vaccine. Using the same platform, we have shown our Ebola vaccine to protect 100% of rhesus monkeys against death caused by Ebolavirus upon a single-dose vaccination, and more recently, that a single dose of our Lassa Fever vaccine also induced 100% protection in mice against intracranial challenge."

About GeoVax
GeoVax Labs, Inc. is a clinical-stage biotechnology company developing human vaccines against infectious diseases using its MVA-VLP vaccine platform. The Company's HIV-1 vaccine for the clade B, the dominant subtype in the Americas, Western Europe and Australia, is advancing in human trials conducted by the HIV Vaccine Trials Network (HVTN). Preclinical programs are focused on preventive vaccines for ZIKV, hemorrhagic fever viruses (Ebola, Sudan, Marburg, and Lassa), and malaria, as well as therapeutic vaccines for HIV, chronic Hepatitis B infections and cancers. GeoVax's vaccine platform supports in vivo production of non-infectious VLPs from the cells of the very person receiving the vaccine, mimicking a natural infection and stimulating both the humoral and cellular arms of the immune system to recognize, prevent, and control the target infection. For more information, visit www.geovax.com.

Forward-Looking Statements
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