Testing of viscous anti-HIV microbicides using Lactobacillus

• Published in: Journal of microbiological methods 2012-02, Vol.88 (2), p.292-296
• Main Authors: Moncla, B.J., Pryke, K., Rohan, L.C., Yang, H.
• Format: Article
• Language: English
• Subjects: Adenine - analogs & derivatives; Adenine - pharmacology; Anilides - pharmacology; Animals; antagonists; Anti-HIV Agents - chemistry; Anti-HIV Agents - pharmacology; Anti-Infective Agents, Local - chemistry; Anti-Infective Agents, Local - pharmacology; antiretroviral agents; Bacillus atrophaeus; Bacterial quantitation; Biological and medical sciences; blood serum; bovine serum albumin; Cattle; CCR5 receptor; Chemokine CCL5 - pharmacology; Colony Count, Microbial; drugs; Excipients - chemistry; Excipients - pharmacology; Female; Fundamental and applied biological sciences. Psychology; Furans - pharmacology; gels; glycerol; heat inactivation; HIV; HIV infections; Human immunodeficiency virus; Humans; Lactobacillus; Lactobacillus - drug effects; Lactobacillus jensenii; Microbial Sensitivity Tests; Microbial Viability - drug effects; Microbicide; Microbiology; mixing; Organophosphonates - pharmacology; Pyrimidines - pharmacology; RNA-directed DNA polymerase; Serum Albumin, Bovine; spores; Techniques used in virology; Tenofovir; Thioamides; toxicity; toxicity testing; Vagina - microbiology; viability; Virology; Viscosity; Vortex mixing
• ISSN: 0167-7012; 1872-8359
• DOI: 10.1016/j.mimet.2011.12.013

The development of topical microbicides for intravaginal use to prevent HIV infection requires that the drugs and formulated products be nontoxic to the endogenous vaginal Lactobacillus. In 30min exposure tests we found dapivirine, tenofovir and UC781 (reverse transcriptase inhibitor anti-HIV drugs) as pure drugs or formulated as film or gel products were not deleterious to Lactobacillus species; however, PSC-RANTES (a synthetic CCR5 antagonist) killed 2 strains of Lactobacillus jensenii. To demonstrate the toxicity of formulated products a new assay was developed for use with viscous and non-viscous samples that we have termed the Lactobacillus toxicity test. We found that the vortex mixing of vaginal Lactobacillus species can lead to reductions in bacterial viability. Lactobacillus can survive briefly, about 2s, but viability declines with increased vortex mixing. The addition of heat inactivated serum or bovine serum albumin, but not glycerol, prevented the decrease in bacterial viability. Bacillus atrophaeus spores also demonstrated loss of viability upon extended mixing. We observed that many of the excipients used in film formulation and the films themselves also afford protection from the killing during vortex mixing. This method is of relevance for toxicity for cidal activities of viscous products. ► The standard Lactobacillus toxicity test for anti-HIV microbicides is presented. ► Vortex mixers may kill large numbers of organisms and result in false values. ► Non-nucleoside reverse transcriptase inhibitors should continue development. ► Polyvinyl alcohol based films are safe and not deleterious to Lactobacillus. ► Film based anti-HIV microbicides should continue development.