April 5, 2019
GeoVax Labs says the malaria vaccine it is developing with Leidos could achieve efficacy levels called for by the WHO.
US firms GeoVax and Leidos agreed to develop a P. falciparum vaccine in March, expanding on an R&D partnership they formed last November.
Under the deal, GeoVax will make a vaccine able to deliver DNA coding for parasite proteins. Cells ‘infected’ by the vaccine will express the proteins, provoking an immune response.
Image: iStock/Manjurul
Leidos spokeswoman Erin Tindell told us the DNA sequences will be for ‘liver-stage’ P. falciparum proteins that generate a strong, class I (CD8 T cell) immune response.
“The initial work with GeoVax will be a proof-of-concept study to determine if such an immune response can be elicited at high levels. If this is the case, project expansion is planned,” she said.
GeoVax’s vaccines are live viruses – modified vaccinia Ankara (MVA) – filled with genetic material coding for protein antigens that are detected by the recipient’s immune system.
A spokesperson said, “The GeoVax MVA platform is replication competent in avian cells, which are used for cost effective manufacture, but replication deficient for humans, providing a high margin of safety.”
GeoVax has already developed a smallpox vaccine and is working on vaccines against Zika virus and various haemorrhagic-fever causing filoviruses.
In 2013, the World Health Organisation (WHO) called for the development of better protective jabs in an updated version of its malaria vaccine road map.
It wrote, “The world should aim to have vaccines which reduce malaria cases by 75%, and are capable of eliminating malaria, licensed by 2030.”
So far, development efforts have fallen short of the target.
For example GSK’s Mosquirix (RTS,S/AS01) – the sole malaria vaccine approved by the EMA – only reduces incidence of the disease by 50%.
The problem – GeoVax says – is that many of the candidate vaccines in development aim to induce immunity to single targets, rather than multiple proteins from several stages of the malaria parasite’s life-cycle.
The spokesman told us, “Given that the single antigen malaria vaccines tested thus far have not met the aims of the Roadmap, development of multi-antigen malaria vaccines using platforms that can accommodate multiple transgenes from various stages of malaria parasite, is a key strategy in malaria vaccine innovation.”
“The GeoVax MVA platform can stably carry and deliver multiple transgenes and/or multimeric proteins. Moreover, MVA-based malaria vaccines can be used in combination with other malaria vaccines/platforms to increase efficacy overall.”
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