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Osel scientists engineer vaginal lactobacillus to express neutralizing HIV-1 antibody fragments

March 24, 2016

Mountain View, CA (March 24, 2016): A normal, predominant bacterial species of the healthy vaginal microbiota can be engineered for potential use as a novel protective agent against HIV-1 transmission in women, according to a new publication from scientists at Osel, Inc. and their collaborators. The authors describe the engineering of Lactobacillus jensenii to stably express broadly neutralizing antibody fragments against the HIV-1 virus in an advanced online publication of AIDS Research and Human Retroviruses, entitled "Expression of HIV-1 Neutralizing Antibody Fragments Using Human Vaginal Lactobacillus."

Eradicating HIV-1 through the use of a vaccine that produces broadly neutralizing antibodies has been the ultimate goal for HIV prevention, however generating appropriate immune responses via vaccine strategies has proven difficult.

"Most viruses enter the human body through muscosal surfaces, and in women, the vagina and cervix are the major sites of entry for HIV-1 during sexual intercourse," said Laurel Lagenaur, Ph.D, senior author and Director of Research at Osel. "Lactobacilli already play a protective role in the vagina by reducing inflammation, which is a risk factor for HIV infection. Engineering these bacteria to deliver HIV-1 neutralizing antibodies mucosally at the site where the virus first enters the body may offer a cost-effective and long-lasting new barrier to HIV-1 transmission that is different but compatible with current antiviral therapies, barrier methods or future vaccines."

Osel scientists have previously demonstrated that Lactobacillus could be engineered to secrete another anti-HIV-1 protein. They also demonstrated that successful vaginal colonization by the engineered bacterium reduced vaginal HIV transmission in a primate animal model by over 63%.

"Engineered vaginal Lactobacilli with anti-HIV properties, like the delivery of neutralizing antibodies or antiviral proteins, offer considerable potential as Live Biotherapeutic Products for an important global health need -- reducing the heterosexual transmission of HIV in women," said K.T. Moortgat, Ph.D., Osel Chief Executive Officer. "If successfully developed, Osel's MucoCept technology could provide an accessible and durable approach that could be used inexpensively, discretely, and in a way that enhances the natural protective effects of the vaginal microbiota. Osel's MucoCept technology is currently in pre-clinical development, and we expect to progress to clinical testing within the next 2 years."
This work was funding in part by the Bill and Melinda Gates Foundation through a Grand Challenges Explorations Grant and an NIH Small Business Innovative Research grant.

About MucoCept Technology

The mucosal surfaces of the vagina and cervix are colonized with a natural microbiota, mainly Lactobacillus, which help to protect the mucosa. Lactobacilli produce lactic acid, which lowers vaginal pH and promotes a healthy epithelium. These bacteria also appear to have a role in immune modulation, by reducing inflammation. Vaginal inflammation is a risk factor for Human Immunodeficiency Virus type 1 (HIV-1) infection because inflammatory cells are targets for the virus, which enters the body during sexual intercourse through the vaginal and cervical mucosa.

Osel's MucoCept Technology platform aims to leverage this natural microbiota of the vagina and cervix and enhance it to prevent infection from HIV by engineering one microbial component, Lactobacillus jensenii, to produce anti-viral proteins or anti-HIV antibodies capable of neutralizing the virus. If successfully developed, this approach could provide a potent weapon against the heterosexual transmission of HIV that is coitally independent, inexpensive and potentially long lasting. The MucoCept platform also offers the potential to target other viral pathogens, as well as bacteria and fungi. It can furthermore be directed to express antibodies to modulate inflammation or target cancer.

About Osel, Inc.

Osel, Inc., a privately held biotechnology company, is focused on the development and commercialization of a broad portfolio of Live Biotherapeutic Products (LBPs) that prevent or treat medical conditions resulting from a disruption of the human microbiome. In 2003, Osel became one of the first companies to receive U.S. Food and Drug Administration authorization to test a live bacterial therapeutic, and the company is a pioneer in the field of LBPs. The company's proprietary approach identifies differences between healthy and disease-related microbiomes and leverages beneficial microbes to treat problematic disruptions or dysbioses. Osel's approach of repopulating the disrupted microbiome with beneficial bacteria helps to restore a healthy and protective microbiota.

Osel's primary focus is women's health, with initial areas of interest including recurrent urinary tract infections and bacterial vaginosis. The company's secondary focus is disorders of the gastrointestinal tract. The company has two clinical stage products and ongoing Phase 2 clinical trials in these areas. Osel also has a LBP-based technology platform, MucoCept, directed to the prevention of HIV transmission. Osel is based in Mountain View, CA. For more information, please visit the company's website at

Media Contacts:

Joan Kureczka, 415-821-2413

Nicole Litchfield, 415-793-6468


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