Scientists launch bid to save cattle herds in Africa

Source:Xinhua Published: 2014-1-31 17:53:51

A team of scientists from the Nairobi-based research institution has formed a global consortium to help save millions of domestic cows from a killer parasite that plagues some 11 sub-Saharan Africa countries by developing a vaccine.

The International Livestock Research Institute (ILRI) said on Friday the consortium funded by the Bill & Melinda Gates Foundation will develop the highly advanced cattle vaccine to battle East Coast fever.

"We need to get better control of East Coast fever because there are millions of people in East and Central Africa whose existence depends on healthy cattle, and right now they are losing about one animal every 30 seconds to this disease," said Vish Nene, who leads ILRI's Vaccine Biosciences Program and heads up this "improved vaccines for the control of East Coast fever" initiative.

Nene said initial discussions are already underway with malaria vaccine experts, who are eager to see their livestock-oriented colleagues test these novel vaccine approaches in the fight against a similar protozoan disease.

East Coast fever is a devastating cancer-like disease of cattle that often kills the animals within three weeks of infection. The vaccine can also help malaria and cancer research in humans.

It is caused by the single-celled parasite Theileria parva, which is transmitted by the brown ear tick (Rhipicephalus appendiculatus) as it feeds on cattle.

The disease was first recognized in southern Africa when it was introduced at the beginning of the twentieth century with cattle imported from eastern Africa, where the disease had been endemic for centuries, DFID said.

The disease is spreading rapidly and currently threatens some 28 million cattle in East and Central Africa.

It killed more than one million cattle in 11 countries -- Burundi, the Democratic Republic of Congo, Kenya, Malawi, Mozambique, Rwanda, Sudan, Tanzania, Uganda, Zambia and Zimbabwe -- and caused 300 million US dollars in losses in 2013.

ILRI said the researchers will focus on recent breakthroughs that have isolated proteins in the parasite, called antigens, likely to be crucial in protecting cattle from East Coast fever to develop the vaccine. Some of the antigens appear capable of stimulating production of protective antibodies.

Other parasite antigens could help endow the vaccine with the capacity to stimulate the cow's production of a type of lymphocyte known as cytotoxic or "killer" T cells that are able to target and destroy the cow's white blood cells infected with the parasite.

Statistics indicated that about 70 percent of the human population of sub-Saharan Africa depend on livestock for their livelihoods, with farming and herding families relying on cattle for vital sources of food, income, traction, transportation and manure to fertilize croplands.

The East Coast fever team will ensure that the vaccine is made available, accessible and affordable to livestock keepers who need it most and to scale up its production for the future.

Many of the animals threatened by the disease -- which typically kills cows within three to four weeks of infection -- belong to poor pastoralist herders and smallholder farmers for whom the loss of even one cow can be disastrous.

ILRI said the drug is too costly for most African livestock- keepers. And treated animals, while they might recover from severe disease, are often weaker and less productive.

"However, like the drug, the vaccine's cost, 8 dollars to 12 dollars per animal--is too high for many pastoralists and smallholder farmers," ILRI said.

"Also limiting its wider adoption are its strict refrigeration requirements, its production difficulties -- it takes 18 months to make a single batch of vaccine -- and the fact that inoculated animals still carry and transmit the East Cost fever parasite."

The current vaccine, developed by the Kenya Agricultural Research Institute (KARI) with several decades of support from ILRI and many of its partners in the current project, is made essentially by grinding up ticks infected with the parasite that causes East Coast fever.

This "first-generation" vaccine is credited with saving 620,000 cows and a formulation released in 2012 has been in high demand by livestock keepers.

According to ILRI, currently available are both a drug to treat East Coast fever and a vaccine to prevent it and while both are essential in controlling the disease currently, major shortcomings limit their use.

"Working with this first-generation vaccine has taught us a lot about how animals develop immunity to East Coast fever and we hope to translate this knowledge into a more practical and affordable vaccine capable of protecting cattle and preventing them from spreading the parasite," said Ivan Morrison, an expert in cattle immunology at the Roslin Institute.

The Nairobi-based ILRI has become a hub for development of livestock vaccines against diseases that threaten farm animals in the developing world.

ILRI and its partners are also marshalling efforts to develop novel vaccines for African swine fever, peste des petits ruminants (goat plague), contagious bovine pleuropneumonia (lung plague) and Rift Valley fever.

The team will devote part of its work to improving the existing vaccine so that it can serve as a more effective interim solution while the new vaccine is in development--a process which could take about 10 years.

"It's exciting to work on a project that offers enormous benefits for poor livestock-keepers while also providing insights for burdensome human diseases," said Jimmy Smith, director general of ILRI

"It's a sort of back to the future benefit," he added, "because it's only been in the last century that human and veterinary medicine have diverged, when in fact, they have a lot to offer one another."

East Coast fever and malaria are both caused by single-celled parasites, which have proven extremely tough to control.

Like the researchers working on East Coast fever, malaria vaccine scientists are interested in developing formulations that deliver a similar one-two punch to the malaria parasite by simultaneously prompting the production of antibodies and killer T cells.

Posted in: Biology

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