Since condom use is limited in sub-Saharan Africa there is a need to create methods to prevent the spread of HIV that are affordable and usable by women. Topical microbicides have been considered a possibility but have been hindered by the cost of producing them in sterile environments.
However, research published online on March 30 in the Proceedings of the National Academy of Sciences suggests that producing the microbicide in plants is a scaleable and affordable method.
The researchers grew griffithsin (GRFT), a potent HIV entry inhibitor found in red algae, in Nicotiana benthamianaand managed to achieve yields not previously seen.
More than 1g of GRFT-P (plant produced GRFT) per 1kg of leaf tissue was produced, which is significantly higher than previous yields achieved in Escherichia coli. Furthermore, this was extracted using a very simple three step purification process that resulted in a protein with greater than 99 per cent purity.
Following the purification process the researchers obtained GRFT-P yields of 300mg/kg fresh weight, which meant that the 9,300 plants that were used produced 100,000 doses of microbicide.
This could be scaled up to meet demand and keep costs down, with the researchers believing the cost of a dose could be comparable to that of a condom.
GRFT-P shows promise; clinical trials planned
The GRFT-P produced was demonstrated to be effective against HIV and previous work has shown that it has other traits that make it suitable for use as a microbicide.
Primarily this is focused on its stability and 80ºC melting point, which should mean it remains effective after shipping and storage in resource poor areas. In addition GRFT-P can withstand low pH, organic solvents, multiple freeze–thaw cycles, lyophilisation, and reducing agents.
The microbicide has also been shown to remain effective against HIV for at for at least 24 h in cervicovaginal lavages from macaques. It is now hoped that funding will be found and clinical trials initiated.
Kentucky Bioprocessing was also involved in the research paper and has been named as the company to manufacture doses for clinical trials.
The complete research paper can be found here.