A Plant‐Produced Candidate Subunit Vaccine Reduces Shedding of Enterohemorrhagic Escherichia coli in Ruminants

Abstract

Enterohemorrhagic Escherichia coli (EHEC) are commonly present in the gastrointestinal tract of cattle and cause serious infectious disease in humans. Immunizing cattle against EHEC is a promising strategy to decrease the risk of food contamination; however, veterinary vaccines against EHEC such as Econiche have not been widely adopted by the agricultural industry, and have been discontinued, prompting the need for more cost-effective EHEC vaccines. The objective of this project is to develop a platform to produce plant-made antigens for oral vaccination of ruminants against EHEC. Five recombinant proteins were designed as vaccine candidates and expressed transiently in Nicotiana benthamiana and transplastomically in Nicotiana tabacum. Three of these EHEC proteins, NleA, Stx2b, and a fusion of EspA accumulated when transiently expressed. Transient protein accumulation was the highest when EHEC proteins were fused to an elastin-like polypeptide (ELP) tag. In the transplastomic lines, EspA accumulated up to 479 mg kg in lyophilized leaf material. Sheep that were administered leaf tissue containing recombinant EspA shed less E. coli O157:H7 when challenged, as compared to control animals. These results suggest that plant-made, transgenic EspA has the potential to reduce EHEC shedding in ruminants.

Transient Expression of Dengue Virus NS1 Antigen in Nicotiana benthamiana for Use as a Diagnostic Antigen

“…It has been shown that hydrophobins also increase protein accumulation when coupled to recombinant proteins through a similar protein body-inducing mechanism (Joensuu et al, 2010;Saberianfar et al, 2015). Although a previous study has demonstrated that the fusion to HFBI or ELP had similar effects over the accumulation level of the EspA protein from enterohemorrhagic E. coli (Miletic et al, 2017), the same effect could not be seen for the ER targeted DENV NS1. Our results corroborate the findings from Phan and colleagues (2014), which have shown that ELP, but not HFBI, fusion to hemagglutinin increases accumulation levels of the produced protein.…”