Women bear the brunt of the global AIDS epidemic due in part to their inherent social and biological vulnerability. Biologically, the cervical and vaginal mucosae are vulnerable targets for HIV transmission. In healthy women of childbearing age, mucosal antibodies and microbiota, including Lactobacillus jensenii, help protect these surfaces and serve to block the colonization and infection by intruding pathogens. Epidemiological studies suggest that the loss of vaginal lactobacilli is associated with an increased risk of heterosexual HIV-1 transmission and other sexually transmitted infections. Osel, Inc. has used the properties of these natural protective agents by engineering a native human vaginal Lactobacillus , L. jensenii 1153, to express potent and broadly neutralizing single domain antibodies directed against HIV, termed MucoCept-Ab. Osel recently showed proof-of-concept for this recombinant Lactobacillus approach, by expressing an HIV-1 entry inhibitor mCV-N, from L. jensenii, which reduced SHIV virus transmission in macaques by 63% (Lagenaur et al., Mucosal Immunol, (Jul 6, 2011)). Phase II studies will advance MucoCept-Ab through preclinical development. These studies will focus on developing a safe, efficacious, and stable MucoCept-Ab product, and will include strain optimization, formulation, process development, manufacturing, preclinical safety testing, and efficacy testing in a nonhuman primate (NHP) viral challenge model. The goal of this Phase II is to develop a Lactobacillus strain capable of delivering an antibody locally to prevent HIV infection at the vaginal or rectal mucosa. This strain will be formulated into a cost-effective product capable of persistent protection that is coitally-independent and controlled by women.
Aim 1 : MucoCept-Ab API optimization and characterization: A) Complete MucoCept-Ab strain optimization: maximize promoter strength, optimize codons for L. jensenii, remove epitope tag, and test two genomic integration sites; B) Complete microbiological characterization of the MucoCept-Ab strain;genetic stability, sequence chromosomal insertion site of expression cassette, biochemical profiling, antibiotic susceptibility/resistant profiling;AP-m36.4 expressio levels; C) Establish ability of the MucoCept-Ab strain to vaginally colonize female rhesus macaques.
Aim 2 : MucoCept-Ab method development: A) Develop antibodies and ELISA to detect and measure AP-m36.4 levels; B) Develop qPCR assay to measure levels of the MucoCept-Ab strain.
Aim 3 : MucoCept-Ab formulation, process development, and manufacturing: A) Develop formulation and lyophilization process for production of a stable MucoCept-Ab product; B) Transfer MucoCept-Ab strain and technology to GMP manufacturer for production of MCB and WCB, scale up process development, and production of MucoCept-Ab for preclinical safety studies.
Aim 4 : MucoCept-Ab preclinical safety and efficacy: A) Evaluate acute toxicity and systemic exposure of the MucoCept-Ab strain and purified AP-m36.4 protein following vaginal administration in mice; B) Evaluate acute toxicity of formulated MucoCept-Ab in the rabbit vaginal irritation model; C) Evaluate subchronic toxicity, vaginal colonization, and AP-m36.4 levels following vaginal administration of the MucoCept-Ab product in female rhesus macaques; D) Evaluate efficacy of the MucoCept-Ab product in female rhesus macaques using a repeated vaginal SHIV challenge protocol. If successful, this approach could provide a safe, yet inexpensive means to deliver passive immunity against HIV to the vaginal mucosa and to address the urgent need for female-controlled approaches to prevent sexually transmitted viral infection.
We are harnessing the vaginal microbiota to develop a fundamentally new female- controlled and coital-independent HIV preventative. Technologies have been developed to bioengineer a human vaginal Lactobacillus strain to express a potent single domain antibody against HIV, creating a live, self-renewing microbicide that can be formulated as a novel fast-dissolving vaginal tablet. This product is mechanistically different from other microbicides and has the potential to greatly impact global HIV/AIDS acquisition in women of childbearing age.