Engineering attenuation

By exploiting a malaria parasite's "Achilles heel," researchers in Germany say a transgenic whole-organism vaccine for humans may be possible. A group headed by Stefan H.I. Kappe at Heidelberg University School of Medicine induced complete protection against malaria in mice by infecting them with living Plasmodium berghei lacking a single gene, known as UIS3 (for upregulated in infectious sporozoites gene 3).¹ But safety and production issues could prevent the development of the vaccine for humans, say others.

Kappe's group had previously identified UIS3 as being essential for early liver-stage development of the parasite. Sporozoites lacking the gene were not able to develop fully through the liver cycle and induce blood-stage infection. Repeated injections with the sporozoites never resulted in the animals developing malaria, Kappe says.

X-ray irradiation-attenuated Plasmodium falciparum parasites can protect humans from blood-stage infection and disease, notes Filip Dubovsky of the Malaria Vaccine Initiative (MVI). "[But] this...