Development of vaccines to East Coast Fever

Baker’s yeast has been man’s friend for thousands of years. A faithful microbe that helped in times of hunger, thirst and sickness.  Will yeast help man’s other friend – the cow?  The ECF consortium aims to create a subunit vaccine for an infection caused by the parasite Theileria parva (T. parva) by bringing together different experts in the life sciences. On the surface it appears to be an “everything-but-the-kitchen-sink” approach, but the truth is a carefully assembled team of highly skilled people who lose sleep over details and loopholes (a.k.a scientists).  Researchers from the RVC propose yeast as a possible solution.  But why yeast over other Trojan horse vaccines? Yeast is just the right amount of “bad” – it alerts immune cells to its presence but does not actually harm the host in any way, it is easy and cheap to grow, and most importantly it can still activate immune cells when it is dead so it is incredibly stable – bullheaded even (pun intended).  

In the last 9 years, yeast has been tested as a way to help immune cells see and react to human pathogens such as hepatitis C virus, and cancer. Yeast has also helped chickens survive coccidiosis and pigs survive porcine circovirus infection.  The researchers are now persuading yeast to wear a coat decorated with T. parva trophies and train cattle immune cells to react appropriately (in this case to kill T. parva).

Early experiments using cattle cells grown in vitro indicate yeast is doing just that. T. parva-decorated yeast were presented to CD8 T cells and CD4 T cells so that they are sending signals and multiplying as desired. The second test of capability will be done in mice experiments to see if CD8 and CD4 T cells within the animal will do the same thing. Finally yeast need to be tested in cows to see if it protects against T. parva infection.  However, the cow can be as bullheaded as yeast, and T. parva can be cancerous to the core making it difficult to say how the cow or T. parva will respond to our schemes and trickery. One may remain outsmarted by T. parva and will only take home clues as to what else to try in the future.

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