Secretion of Anti-Plasmodium Effector Proteins from a Natural Pantoea agglomerans Isolate by Using PelB and HlyA Secretion Signals

Abstract

The insect-vectored disease malaria is a major world health problem. New control strategies are needed to supplement the current use of insecticides and medications. A genetic approach can be used to inhibit development of malaria parasites (Plasmodium spp.) in the mosquito host. We hypothesized that Pantoea agglomerans, a bacterial symbiont of Anopheles mosquitoes, could be engineered to express and secrete antiPlasmodium effector proteins, a strategy termed paratransgenesis. To this end, plasmids that include the pelB or hlyA secretion signals from the genes of related species (pectate lyase from Erwinia carotovora and hemolysin A from Escherichia coli, respectively) were created and tested for their efficacy in secreting known antiPlasmodium effector proteins (SM1, anti-Pbs21, and PLA2) in P. agglomerans and E. coli. P. agglomerans successfully secreted HlyA fusions of anti-Pbs21 and PLA2, and these strains are under evaluation for anti-Plasmodium activity in infected mosquitoes. Varied expression and/or secretion of the effector proteins was observed, suggesting that the individual characteristics of a particular effector may require empirical testing of several secretion signals. Importantly, those strains that secreted efficiently grew as well as wild-type strains under laboratory conditions and, thus, may be expected to be competitive with the native microbiota in the environment of the mosquito midgut.

Mosquito/microbiota interactions: from complex relationships to biotechnological perspectives

“…Recently, Pantoea agglomerans, another bacterial symbiont of Anopheles mosquitoes has been engineered to express and secrete anti-Plasmodium effector proteins, such as pelB or hlyA, from related species [67]. These strains are now under evaluation for anti-Plasmodium activity in infected mosquitoes.…”

Symbiotic control of mosquito borne disease

“…More recently, Pantoea agglomerans, a bacterial symbiont of Anopheles mosquitoes, has been engineered to express and secrete anti-Plasmodium effector proteins. 13 The successful expression and secretion of anti-malaria molecules indicates P. agglomerans as a potentially useful tool for malaria paratransgenic control. This has been demonstrated by a study that used engineered P. agglomerans strains expressing some anti-Plasmodium effector molecules that inhibited development of the human malaria parasite Plasmodium falciparum and rodent malaria parasite P. berghei by up to 98% in vivo.…”

Expression and extracellular release of a functional anti-trypanosome Nanobody® in Sodalis glossinidius, a bacterial symbiont of the tsetse fly

“…The feasibility of expressing ScFvs in bacterial symbionts that retain their functional activities has been demonstrated in Rhodococcus [13] and Pantoea agglomerans [7]. However, due to their bulky size (30 kDa range) and complex architecture mAbs are often prone to aggregation and reduced affinity [14,15].…”