Furthermore, long term protection greater than 3 years was afforded by vaccination. T. vaginalis is an extracellular parasite and elimination of this parasite will most likely be Ig dependent. While cellular mediated immunity could play a role it is unlikely to be as effective as a strong neutralizing and parasitotoxic humoral response. It would not be expected that high concentrations of specific Ig be detected in vaginal washings

following immunization, but a realistic goal for vaccine efficacy would be an anamnestic response following intravaginal challenge/infection, as has been shown for T. foetus immunization in the bovine model [67]. selleck chemical Complement lysis has also been shown effective in killing Tv [57]. The composition of the immune response, whether IgA, IgG or a combination, the subclass of IgG, and the role of complement activation important for protection will require correlational studies in an animal model as well as human data. Unfortunately an animal model of vaccine efficacy is not always a predictor of success in humans. Questions STI571 datasheet remain regarding Tv vaccination studies: what is the

durability of the immune response and protection, and is cross isolate protection conferred? Once a vaccine formulation is determined to be safe and is approved for human testing [77], we can then initiate a phase 1 healthy volunteer study with a small female cohort to determine the safety and the short and long term efficacy of a potential vaccine. Since drug treatment is available to cure susceptible Tv infection we could theoretically vaccinate volunteers and then attempt a challenge with Tv too and monitor infection status, disease progression, and immune response (local vaginal

and systemic) over a predetermined period of time. Durability of immune response can be studied by varying the infection challenge over different timepoints. Alternatively, high risk populations, typically female sex workers (FSW), could be vaccinated and followed over a short period to monitor differences in Tv incidence versus a control unvaccinated group of FSW. Long lasting inducible immunity can be measured by following the same FSW over a number of years. By utilizing different Tv isolates for infection challenge we can test the ability to provide cross isolate protection. Alternatively, a vaccine developed with a clinical isolate from one geographic region could be tested for efficacy in another region with defined endpoints of the ability to prevent or clear an infection. A pivotal ethical concern is the ability to easily cure an induced infection. Thus the use of isolates which are very susceptible to metronidazole in these experiments is essential. Costs associated with producing and testing vaccines are considerable.