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A vaccine candidate generated using algae may be able to prevent the transmission of malaria from infected hosts to mosquitoes, preclinical research suggests.
Researchers used Chlamydomonas reinhardtii microalgae to produce recombinant Pfs25 protein.
When paired with human-compatible adjuvants—glucopyranosal lipid A (GLA) plus squalene oil-in-water emulsion—the protein generated antibodies that nearly eliminated malaria infection in mosquitoes.
The researchers reported these results in Infection and Immunity.
“Most malaria vaccine approaches are aimed at preventing humans from becoming infected when bitten by mosquitoes that carry the parasite,” said study author Joseph Vinetz, MD, of the University of California, San Diego.
“Our approach is to prevent transmission of the malaria parasite from infected humans to mosquitoes. This approach is similar to that of the current measles vaccine, which is such a hot topic of discussion these days, because the goal is to generate herd immunity in a population. We think that this approach is key to global malaria elimination too.”
Dr Vinetz and his colleagues wanted to produce a large quantity of properly folded Pfs25, a protein found on the surface of the malaria parasite’s reproductive cells, which are only present within the mosquito’s gut after it feeds on a malaria-infected blood meal.
Since antibodies against Pfs25 can halt the parasite’s lifecycle in the mosquito, they might also block transmission of the parasite to the next host. However, properly folded Pfs25 that induces transmission-blocking antibodies has been difficult to produce in the lab.
To overcome this problem, the researchers turned to Chlamydomonas reinhardtii. They introduced the Pfs25 gene into the algae by shooting the DNA into the plant cell’s nucleus.
After they let the algae do the work of replicating, building, and folding the protein, the team was able to purify enough functional Pfs25 for testing.
They also tested different adjuvants, which help stimulate the immune system’s response to Pfs25. They tested alum alone, GLA plus alum, squalene oil-in-water emulsion, and GLA plus squalene oil-in-water emulsion.
The best Pfs25/adjuvant combination—GLA plus squalene oil-in-water emulsion—elicited a uniquely robust antibody response in mice with high affinity and avidity—antibodies that specifically and strongly reacted with the malaria parasite’s reproductive cells.
The researchers then fed mosquitoes malaria parasites in the presence of control serum or immune serum collected from mice vaccinated with algae-produced Pfs25 in the presence of the adjuvants.
Eight days later, the team examined the mosquitoes’ guts for the presence of the malaria parasite. And they found that 4.2% (1/24) of mosquitoes that consumed the Pfs25/adjuvant-treated mouse serum were positive for the malaria parasite, compared to 70% (28/40) of control mosquitoes.
“We are really excited to see that Pfs25 produced by algae can effectively prevent malaria parasites from developing within the mosquito,” said study author Stephen Mayfield, PhD, of the University of California, San Diego.
“With the low cost of algal production, this may be the only system that can make an economic malaria vaccine. Now, we’re looking forward to comparing algae-produced Pfs25 and adjuvant head-to-head against other approaches to malaria vaccine production and administration.” 
Image from Bielefeld University
A vaccine candidate generated using algae may be able to prevent the transmission of malaria from infected hosts to mosquitoes, preclinical research suggests.
Researchers used Chlamydomonas reinhardtii microalgae to produce recombinant Pfs25 protein.
When paired with human-compatible adjuvants—glucopyranosal lipid A (GLA) plus squalene oil-in-water emulsion—the protein generated antibodies that nearly eliminated malaria infection in mosquitoes.
The researchers reported these results in Infection and Immunity.
“Most malaria vaccine approaches are aimed at preventing humans from becoming infected when bitten by mosquitoes that carry the parasite,” said study author Joseph Vinetz, MD, of the University of California, San Diego.
“Our approach is to prevent transmission of the malaria parasite from infected humans to mosquitoes. This approach is similar to that of the current measles vaccine, which is such a hot topic of discussion these days, because the goal is to generate herd immunity in a population. We think that this approach is key to global malaria elimination too.”
Dr Vinetz and his colleagues wanted to produce a large quantity of properly folded Pfs25, a protein found on the surface of the malaria parasite’s reproductive cells, which are only present within the mosquito’s gut after it feeds on a malaria-infected blood meal.
Since antibodies against Pfs25 can halt the parasite’s lifecycle in the mosquito, they might also block transmission of the parasite to the next host. However, properly folded Pfs25 that induces transmission-blocking antibodies has been difficult to produce in the lab.
To overcome this problem, the researchers turned to Chlamydomonas reinhardtii. They introduced the Pfs25 gene into the algae by shooting the DNA into the plant cell’s nucleus.
After they let the algae do the work of replicating, building, and folding the protein, the team was able to purify enough functional Pfs25 for testing.
They also tested different adjuvants, which help stimulate the immune system’s response to Pfs25. They tested alum alone, GLA plus alum, squalene oil-in-water emulsion, and GLA plus squalene oil-in-water emulsion.
The best Pfs25/adjuvant combination—GLA plus squalene oil-in-water emulsion—elicited a uniquely robust antibody response in mice with high affinity and avidity—antibodies that specifically and strongly reacted with the malaria parasite’s reproductive cells.
The researchers then fed mosquitoes malaria parasites in the presence of control serum or immune serum collected from mice vaccinated with algae-produced Pfs25 in the presence of the adjuvants.
Eight days later, the team examined the mosquitoes’ guts for the presence of the malaria parasite. And they found that 4.2% (1/24) of mosquitoes that consumed the Pfs25/adjuvant-treated mouse serum were positive for the malaria parasite, compared to 70% (28/40) of control mosquitoes.
“We are really excited to see that Pfs25 produced by algae can effectively prevent malaria parasites from developing within the mosquito,” said study author Stephen Mayfield, PhD, of the University of California, San Diego.
“With the low cost of algal production, this may be the only system that can make an economic malaria vaccine. Now, we’re looking forward to comparing algae-produced Pfs25 and adjuvant head-to-head against other approaches to malaria vaccine production and administration.”
Image from Bielefeld University
A vaccine candidate generated using algae may be able to prevent the transmission of malaria from infected hosts to mosquitoes, preclinical research suggests.
Researchers used Chlamydomonas reinhardtii microalgae to produce recombinant Pfs25 protein.
When paired with human-compatible adjuvants—glucopyranosal lipid A (GLA) plus squalene oil-in-water emulsion—the protein generated antibodies that nearly eliminated malaria infection in mosquitoes.
The researchers reported these results in Infection and Immunity.
“Most malaria vaccine approaches are aimed at preventing humans from becoming infected when bitten by mosquitoes that carry the parasite,” said study author Joseph Vinetz, MD, of the University of California, San Diego.
“Our approach is to prevent transmission of the malaria parasite from infected humans to mosquitoes. This approach is similar to that of the current measles vaccine, which is such a hot topic of discussion these days, because the goal is to generate herd immunity in a population. We think that this approach is key to global malaria elimination too.”
Dr Vinetz and his colleagues wanted to produce a large quantity of properly folded Pfs25, a protein found on the surface of the malaria parasite’s reproductive cells, which are only present within the mosquito’s gut after it feeds on a malaria-infected blood meal.
Since antibodies against Pfs25 can halt the parasite’s lifecycle in the mosquito, they might also block transmission of the parasite to the next host. However, properly folded Pfs25 that induces transmission-blocking antibodies has been difficult to produce in the lab.
To overcome this problem, the researchers turned to Chlamydomonas reinhardtii. They introduced the Pfs25 gene into the algae by shooting the DNA into the plant cell’s nucleus.
After they let the algae do the work of replicating, building, and folding the protein, the team was able to purify enough functional Pfs25 for testing.
They also tested different adjuvants, which help stimulate the immune system’s response to Pfs25. They tested alum alone, GLA plus alum, squalene oil-in-water emulsion, and GLA plus squalene oil-in-water emulsion.
The best Pfs25/adjuvant combination—GLA plus squalene oil-in-water emulsion—elicited a uniquely robust antibody response in mice with high affinity and avidity—antibodies that specifically and strongly reacted with the malaria parasite’s reproductive cells.
The researchers then fed mosquitoes malaria parasites in the presence of control serum or immune serum collected from mice vaccinated with algae-produced Pfs25 in the presence of the adjuvants.
Eight days later, the team examined the mosquitoes’ guts for the presence of the malaria parasite. And they found that 4.2% (1/24) of mosquitoes that consumed the Pfs25/adjuvant-treated mouse serum were positive for the malaria parasite, compared to 70% (28/40) of control mosquitoes.
“We are really excited to see that Pfs25 produced by algae can effectively prevent malaria parasites from developing within the mosquito,” said study author Stephen Mayfield, PhD, of the University of California, San Diego.
“With the low cost of algal production, this may be the only system that can make an economic malaria vaccine. Now, we’re looking forward to comparing algae-produced Pfs25 and adjuvant head-to-head against other approaches to malaria vaccine production and administration.”