Immune response of rats vaccinated orally with various plant-expressed recombinant cysteine proteinase constructs when challenged with Fasciola hepatica metacercariae

Abstract

BackgroundCysteine proteinases of Fasciola hepatica are important candidates for vaccine antigens because of their role in fluke biology and host-parasite relationships. In our previous experiments, we found that a recombinant cysteine proteinase cloned from adult F. hepatica (CPFhW) can protect rats against liver fluke infections when it is administered intramuscularly or intranasally in the form of cDNA. We also observed considerable protection upon challenge following mucosal vaccination with inclusion bodies containing recombinant CPFhW produced in Escherichia coli.In this study, we explore oral vaccination, which may be the desired method of delivery and is potentially capable of preventing infections at the site of helminth entry. To provide antigen encapsulation and to protect the vaccine antigen from degradation in the intestinal tract, transgenic plant-based systems are used.MethodologyIn the present study, we aimed to evaluate the protective ability of mucosal vaccinations of 12-week-old rats with CPFhW produced in a transgenic-plant-based system. To avoid inducing tolerance and to maximise the immune response induced by oral immunisation, we used the hepatitis B virus (HBV) core protein (HBcAg) as a carrier. Animals were immunised with two doses of the antigen and challenged with 25 or 30 metacercariae of F. hepatica.ConclusionsWe obtained substantial protection after oral administration of the plant-produced hybrids of CPFhW and HBcAg. The highest level of protection (65.4%) was observed in animals immunised with transgenic plants expressing the mature CPFhW enzyme flanked by Gly-rich linkers and inserted into c/e1 epitope of truncated HBcAg. The immunised rats showed clear IgG1 and IgM responses to CPFhW for 4 consecutive weeks after the challenge.

Progress in biopharmaceutical development

“…The use of plants eliminates potential contamination of the therapeutic drug with animal pathogens, as plant cell cultures are not susceptible to mammalian viral pathogens and, conversely, plant viruses do not infect human cells . Another advantage is that orally immunogenic recombinant proteins expressed in an edible plant may be orally administered without processing, including expensive purification steps . Moreover, plant expression systems are able to produce proteins with complex glycosylation patterns; however, the glycan structures produced are significantly different from those produced in humans.…”

A Preliminary Study of a Lettuce-Based Edible Vaccine Expressing the Cysteine Proteinase of Fasciola hepatica for Fasciolosis Control in Livestock

“…Based on its previous successful use against F. hepatica infection in rats ( 11 ), a lettuce-based edible vaccine expressing CPFhW fused to an HBcAg carrier was tested in the natural hosts (sheep and cattle). To the best of our knowledge, this study is the first report of the oral vaccination of ruminants with a plant-produced liver fluke antigen.…”

“…The vaccine construct was obtained as previously described ( 11 ). Briefly, cDNA encoding CPFhW (accession no.…”

“…The Weybridge strain of F. hepatica that was maintained in our laboratory was used for the cattle and sheep infections ( 13 ). Metacercariae were obtained as previously described ( 11 ), and their viability was tested prior to infection. Two-month-old metacercariae were used for the infection experiments.…”

“…Substantial protection has been obtained in rats after oral vaccination with lyophilized transgenic lettuce expressing CPFhW CatL fused to a hepatitis B virus core antigen (HBcAg) carrier (up to a 65.5% reduction in the liver fluke burden) ( 11 ). Here, we investigated the potential of a lettuce-based edible vaccine expressing CPFhW fused to HBcAg against subsequent infection with liver fluke metacercariae in the natural hosts of F. hepatica (sheep and cattle).…”