The VTT Technical Research Centre of Finland has developed a water-administered vaccine to treat diarrhea in piglets being weaned.

The VTT-developed vaccine is a new type of product that can replace antimicrobials, such as zinc oxide, used in pig production.

“The vaccine’s production method has proved to be very effective, and it can also be used in the development of other animal vaccines. The method may be available commercially already in the next few years,” said principal scientist Jussi Joensuu of VTT.

The background for this development lies in Joensuu’s 2006 dissertation in which he proved the effectiveness of the vaccine molecule. At that time, the idea was to produce the vaccine molecules in transgenic plants, but the method was not commercially viable, VTT said.

The expression system chosen by VTT was the filamentous fungus Trichoderma reesei. The vaccine is produced by means of a fermentation process in a closed bioreactor.

Before commercial availability, however, the vaccine must be shown in practice to be safe and effective. The first animal test was carried out this summer in Belgium, and the results in terms of efficiency are promising, VTT said.

“When administered in drinking water, the vaccine offers protection exactly where it is needed, namely in the intestine. If the vaccine was injected, most of the antibodies would remain in the bloodstream,” Joensuu said.

While nursing, piglets get protection from the sow’s milk. However, diarrhea can emerge when piglets go from a predominately liquid diet to solid feed, enabling harmful bacteria — usually Escherichia coli — to attach to the intestines, VTT explained. At this stage, the piglet’s own antibody production is only just starting, and pathogenic bacteria can get a foothold in the small intestine, leading to diarrhea.

The affected piglet suffers, its growth slows down and, in extreme cases, the diarrhea can cause death.

The vaccine is administered to piglets in drinking water after weaning. The piglet’s immune system will recognize the vaccine molecule and start creating antibodies against the bacteria. The antibodies will prevent bacteria from attaching to the receptors in the small intestine, thereby preventing diarrhea.

Currently, porcine postweaning diarrhea is prevented by means of diet, hygienic rearing conditions and antibiotics.