A National Taiwan University (NUT) team developed transgenic bananas to orally vaccinate swine against porcine reproductive and respiratory syndrome (PRRS), which they consider a major breakthrough with great economic potential.

This was according to the Republic of China National Science Council (NSC) on July 17.

The team was led by Huang Pung-ling of the NTU Department of Horticulture and Landscape Architecture and Jeng Chian-ren, director of the NTU Graduate Institute of Molecular and Comparative Pathobiology. Its research made the front cover of the April issue of the prestigious Plant Biotechnology Journal.

After PRRS first emerged at the end of the 1980s, it caused serious damage to the hog industry in Europe and the US, and spread to Taiwan in 1991. The disease causes miscarriages, weak newborns and a low litter survival rate, creating serious economic losses, with Taiwan virus strains even more virulent than those found abroad, the NSC said.

NSC said that neither inactivated nor attenuated vaccine forms are effective in activating the pig's immune system. Moreover, vaccines effective against one strain of the disease have limited efficacy against other strains.

The NTU team used genetic engineering technology to transfer some of the virus' genetic material to the banana chromosome. The banana effectively functions as a bioreactor, producing a vegetable oral vaccine. As the time-consuming and costly injection process is avoided, the biovaccine has high economic value, the NSC said.

"Pigs can eat the vaccine as raw food," Huang said. "It is extremely convenient and there is no risk of secondary infection or attenuation of vaccine proteins in the cooking process." He added that the vaccine would be safe and readily prepared.

"Patents have already been secured in Taiwan, the US and mainland China. In the future, the technique could be used to produce vaccines for cattle, sheep and poultry diseases, and possibly even against human illnesses such as hepatitis and influenza."