East Coast fever (ECF) is one of the major diseases affecting cattle and among the major livestock diseases that the Biotech team at ILRI is researching on to develop and improve vaccines for. ECF is caused by a tick-borne parasite called Theileria parva and has been affecting cattle in 11 countries in Eastern, Central and Southern Africa since the early 1900s. The disease is estimated to be causing 1million deaths annually with losses amounting to 300 million US dollars, about 28 million cattle are at risk.
The current control methods to ECF are:
- Tick control by dipping/spraying
- Treatment of sick animals
- Live vaccine: Infection and Treatment and Method (ITM) vaccine also known as Muguga Cocktail
In his seminar presentation yesterday 11 October, titled ‘Understanding the antigenic basis of strain-restricted immunity to T.parva (CIDLID project)’ Roger Pelle, one of the ILRI scientists working on this project gave an update of where the research team was in the study of the various types of T. parva parasites that are in the live vaccine (Muguga Cocktail) and comparing them to what is there in the regions where ECF is endemic. The study regions include Kenya, Uganda, Tanzania, Zambia and Zimbabwe.
Muguga Cocktail, as the name suggests is a ‘cocktail vaccine’ from 3 seed stocks (stabilates):
- T. parva Muguga stabilate
- T. parva Kiambu 5 stabilate
- T. parva Serengeti transformed stabilate
The first batch of the Muguga Cocktail vaccine, FAO1, was produced by ILRI in 1996 and the second and current batch, ILRI08, was produced by ILRI in 2008. The vaccine so far has been very successful and is in high demand especially in Tanzania. The vaccine gives between 95-100% protection against ECF but has some limitations that are driving further research that can lead to the development of an improved vaccine, some of these limitations include;
- Risk of disease if drug fails; carrier state; new strains
- Difficult to administer the vaccine requiring well trained manpower
- Cold chain, vaccine needs to be stored in liquid nitrogen
- Expensive: immunisation costing about USD 9-17/animal
The recent study updates as shared during the presentation is that, there are more different parasites in the study field populations than in the Muguga Cocktail vaccine and by further studying these parasites and comparing them with the current vaccine the team aims to understand the antigenic basis of strain-restricted immunity to T. parva and hopefully identify responsible parasite components that will help develop improved vaccine easier to administer, more affordable to farmers and overcome the above limitations.
This study is a collaborative effort of Universities of Edinburgh and Glasgow and ILRI. For more information about the project visit: http://www.theileria.org/cidlid/
Content Credit: With input from Dr. Roger Pelle, a molecular biologist and scientist in the Vaccines and Diagnostics research programme (BT01) at ILRI. Dr. Pelle has worked on Theileria parva since 2001, and has played a leading role in the studies that led to the identification of CD8 T cell antigens from Theileria parva.
Photo credit: ILRI flickr account (http://www.flickr.com/photos/ilri)