Development of Vaginal Lactobacilli for Mucosal Delivery of a Topical Microbicide, Cyanovirin-N (CV-N)

Background

Women are particularly at risk of HIV infection, therefore, female initiated strategies are essential to curtail the HIV/AIDS pandemic worldwide.

Material and Methods

We developed a live topical microbicide, which is an H2O2-producing Lactobacillus jensenii, a natural component of the vaginal microflora, as a delivery vehicle for the potent HIV inhibitor, cyanovirin-N (CV-N).

Results

The optimized CV-N expression cassette was stably integrated in single copy into the lactobacillus bacterial chromosome, and resolved from extraneous plasmid DNA and antibiotic resistance determinants. The L. jensenii-expressed CV-N dramatically decreased CCR5-trophic HIV_BaL infectivity in vitro, with an IC₅₀ of 0.3 nM. Histological examination of CD1 mice, which were intra-vaginally inoculated with L. jensenii expressing CV-N, revealed that L. jensenii was associated with keratinized epithelium present during estrus or free in the vaginal lumen and secreted full-length CV-N in vivo.

Conclusion

This live microbicide represents a major step towards developing inexpensive, durable protein-based microbicides to address the urgent need for female-controlled approaches to block the heterosexual transmission of HIV.