Medicine:Edible algae vaccine

Short description: Vaccination strategy being researched

Edible algae based vaccination is a vaccination strategy under preliminary research to combine a genetically engineered sub-unit vaccine and an immunologic adjuvant into Chlamydomonas reinhardtii microalgae. Microalgae can be freeze-dried and administered orally. While spirulina is accepted as safe to consume, edible algal vaccines remain under basic research with unconfirmed safety and efficacy as of 2018.

In 2003, the first documented algal-based vaccine antigen was reported, consisting of a foot-and-mouth disease antigen complexed with the cholera toxin subunit B, which delivered the antigen to digestion mucosal surfaces in mice. The vaccine was grown in C. reinhardtii algae and provided oral vaccination in mice, but was hindered by low vaccine antigen expression levels.

Proteins expressed inside the chloroplast of algae (the most common site of genetic engineering and protein production) do not undergo glycosylation, a form of posttranslational modification. Glycosylation of proteins that are not naturally modified like the malaria vaccine candidate pfs25 can occur in common expression systems like yeast.

References

• U.S. Food and Drug Administration (2002) GRAS Notification for Spirulina Microalgae
• Specht, Elizabeth A.; Mayfield, Stephen P. (2014). "Algae-based oral recombinant vaccines". Frontiers in Microbiology 5: 60. doi:10.3389/fmicb.2014.00060. PMID 24596570. 
• Rasala, Beth A.; Muto, Machiko; Lee, Philip A.; Jager, Michal; Cardoso, Rosa M.F.; Behnke, Craig A.; Kirk, Peter; Hokanson, Craig A. et al. (2010). "Production of therapeutic proteins in algae, analysis of expression of seven human proteins in the chloroplast of Chlamydomonas reinhardtii". Plant Biotechnology Journal 8 (6): 719–733. doi:10.1111/j.1467-7652.2010.00503.x. PMID 20230484. 
• Shimp, Richard L.; Rowe, Christopher; Reiter, Karine; Chen, Beth; Nguyen, Vu; Aebig, Joan; Rausch, Kelly M.; Kumar, Krishan et al. (2013). "Development of a Pfs25-EPA malaria transmission blocking vaccine as a chemically conjugated nanoparticle". Vaccine 31 (28): 2954–2962. doi:10.1016/j.vaccine.2013.04.034. PMID 23623858. 
• Gregory, James A.; Li, Fengwu; Tomosada, Lauren M.; Cox, Chesa J.; Topol, Aaron B.; Vinetz, Joseph M.; Mayfield, Stephen; Hviid, Lars (2012). "Algae-Produced Pfs25 Elicits Antibodies That Inhibit Malaria Transmission". PLOS ONE 7 (5): e37179. doi:10.1371/journal.pone.0037179. PMID 22615931. Bibcode: 2012PLoSO...737179G.