Genetically Engineered Banana Plants Vaccinate Swine

NTU researchers have genetically engineered banana plants to feed to hogs as an oral vaccine against a costly swine virus. This plant-based oral vaccine, which the researchers have proven prevents pigs from being infected by the porcine reproductive and respiratory syndrome virus (PRRSV), has attracted attention both here in Taiwan and abroad.

On July 17, the National Science Council held a press conference to spotlight this breakthrough as well as the interdisciplinary team of researchers behind it, which included investigators from the Department of Horticulture and Landscape Architecture and the School of Veterinary Medicine. Moreover, the team’s article introducing their research breakthrough attracted international recognition by being featured as the cover story for the April issue of the Plant Biotechnology Journal .

In the article, the authors pointed out that in future developments of recombinant subunit vaccines, adapting plants will become the main trend in developing a new generation of vaccines. Oral delivery activates the immune response of the mucous membrane and thereby induces the immune response of body fluids and cells, helping the host resist the invasion of external pathogens. Such a vaccine has the advantages of being mass producible, inexpensive, easily preserved, and convenient to administer.

PRRSV has been the cause of significant economic losses for pig breeders ever since it first appreared around 1990. To date, no vaccines capable of warding off the virus have been developed.

The research team selected the banana plant as its gene expression system due to the advantages that it can be grown in most tropical and subtropical climates and can be consumed fresh, making it a good bioreactor. The researchers used recombinant DNA technology to engineer banana plants to express the ORF5 gene of PRRSV envelope glycoprotein (GP5).

The plant vaccine is administered by feeding hogs the leaves of the transgenic banana plants three times at two week intervals. Just three weeks after the initial feeding, the oral vaccine spurs an exclusive immune response to PRRSV in the cells and body fluids of the hogs. The immune response can reach stable levels four weeks after the first feeding. PRRS is effectively repressed in the vaccinated hogs and the hogs’ lungs do not produce indirect pneumonia lesions.

This is the first research demonstrating that banana plant oral vaccines can be used to vaccinate mammals, and that plant-based oral vaccines can prevent many animal diseases, and even human diseases, that are resisted by the immunological system of the mucus membrane.

The research project was promoted by the Office for Industrial Promotion of Agricultural Biotechnology. It received funding from the National Science Council, Council of Agriculture, as well as Reber Genetic Co. and FlySun Development Co., which participated as industry-academia partners.