Vaccines Made from Algae? It's Possible

Vaccines against animal pathogens might one day be made from genetically engineered algae, according to recent studies.

The approach could make it cheaper and simpler to vaccinate animals and humans against many important infections, Sergio Rosales-Mendoza, PhD, a researcher at the Autonomous University of San Luis Potosí in Mexico, writes in a book published earlier this year.

Streamlining the production and delivery of vaccines could help stop outbreaks that threaten the food supply. Vaccines bridge the gap between an ideal, completely biosecure farm and reality, in which complex factors such as antibiotic resistance, exposure to wild animals, and poverty can make it impossible to keep all pathogens from spreading through a herd or flock, according to Dr. Rosales-Mendoza.

Making safe, effective vaccines quickly is equally crucial when fighting emerging zoonoses. “Recent global disease events, such as influenza and Ebola epidemics, highlight the serious impact of zoonotic diseases,” Dr. Rosales-Mendoza writes. Many factors—including intensified farming practices, human population growth, climate change, and the blending of human and wildlife habitats–are now tipping the scales toward zoonotic diseases, he adds.

Current recombinant vaccines tend to be safe and highly effective, but production and delivery methods are expensive and resource-intensive, according to experts. These concerns first propelled scientists to try to make recombinant oral vaccines from edible plants, write researchers at the California Center for Algae Biotechnology at the University of California at San Diego, La Jolla. But technical hurdles and concerns about contaminating the food supply stymied many of these efforts, they add. Researchers then turned to algae, which produces stable cell lines and is easier to contain and to scale up when needed, they assert.

Since then, researchers have begun developing several algae-based vaccines against animal pathogens, including classical swine fever virus, white spot syndrome virus (which infects farmed shrimp and other crustaceans), Taenia solium (the pork tapeworm, which causes cysticercosis), foot-and-mouth-disease virus, and porcine circovirus, according to Dr. Rosales-Mendoza.

Much of this work is in the early stages, but some results are promising. For example, scientists have been able to genetically tweak and clone algae expressing the porcine circovirus antigen and the GK1 peptide from T. solium. Other teams have not only engineered algae that produce important epitopes for classical swine fever virus, but also have induced humoral immunity against the virus in pigs by giving them unadjuvanted oral doses or adjuvanted subcutaneous injections of the cloned algae.

Scientists also have engineered transgenic algae to express a protein that confers immune protection against white spot syndrome virus, Dr. Rosales-Mendoza notes. Remarkably, exposing crayfish to these algae cut their mortality from WSSV by about 40%.

So far, algae are attractive candidates that can produce an array of distinct and functional antigens, he concludes. Other important zoonotic candidates for algae-based vaccines include brucellosis, chlamydophilosis, Q fever, Orf, Escherichia coli O157 infection, Rift valley fever, and bovine spongiform encephalopathy, he argues. Neglected tropical diseases such as leishmaniasis are “another priority goal,” he writes. Most such infections are zoonotic, and targeting them with effective, safe, and inexpensive vaccines made from algae could enable “broad vaccination coverage in host animals in which vaccination is feasible, thus blocking [their] transmission.”

Dr. Amy Karon earned her doctorate in veterinary medicine and master’s degrees in public health and journalism from the University of Wisconsin-Madison. She was an infectious disease epidemiologist and “disease detective” (EIS officer) with the Centers for Disease Control and Prevention before becoming a full-time medical writer. She lives in the San Francisco Bay area, where she volunteers for the local Humane Society.