How Close Are Scientists To A New Anti-Tick Vaccine In Uganda?

In Uganda, researchers are working towards field trials of a vaccine that aims to use proteins from disease-bearing ticks to protect cattle and reduce pesticide use.

Uganda is estimated to suffer an direct and indirect costs of over$1 billion a year from the impacts of ticks and tick-borne diseases, according to a 2021 review, threatening the country’s dairy sector, the second biggest foreign exchange earner after coffee.

Margaret Saimo-Kahwa, senior Lecturer at the College of Veterinary Medicine, Animal Resources and Biosecurity at Uganda’s Makerere University says that diseases from ticks, such as East Coast Fever, Babesiosis, Anaplasmosis and Heartwater cause of high death rates in cattle, leading to higher food insecurity in Africa.

“I’m researching the use of recombinant tick gut proteins identified from local ticks in Uganda, as a way of creating an anti-tick vaccine,” she says adding that the hope is to protect cattle while reducing the use of acaricides (pesticides).

“The vaccine couldn’t have come at a better time, when Uganda is grappling with acaricide resistant ticks, exacerbating tick-borne diseases,” Saimo-Kahwa says, adding that today, the only practical preventative solution to East Coast Fever, has been the unconventional “infection and treatment method” developed in the 1970s.

Although anti-tick vaccines have been produced at scale in Australia, Cuba, Mexico, and Latin America for the past two decades, roll-out in sub-Saharan Africa has been hindered by their lack of efficacy against tick strains native to the region.

She explains that the genetic sequences of the tick gut protein variants (Ra92A and Ra85A) were synthesized into a yeast host: Pichia pastoris — and the team has already built the technological capacity to produce these proteins and formulate them into a patent-pending candidate vaccine at a newly upgraded production facility.

“Once we mass produce these batches from our specialized vaccine line, we aim to test them in the field to access their immunogenicity, safety and efficacy in large numbers of cattle against all important tick species from the different geographical regions of Uganda,” Saimo-Kahwa says, “Once we have achieved this, we will have developed locally in Uganda a conventional anti-tick vaccine ready not just for commercial up-scaling, but one which has cross-species protection against other tick infestations, on top of developing cGMP compliant vaccine production capacity, a first in Uganda and Africa.”

Ugandan Solutions

Saimo-Kahwa grew up in the small Budaka district in eastern Uganda,

After going through the Ugandan school system, she graduated with a bachelor of Veterinary Medicine at Makerere University in Kampala, Uganda and a master’s degree in Applied Immunology at Brunel University in London, UK.

“It wasn’t until 2005 when I received funding for a sandwich program at Makerere University and Wageningen University, the Netherlands, that I embarked on a PhD at Makerere University with interest in tick proteins with potential for candidate vaccines took shape,” Saimo-Kahwa says, adding that during her PhD work, she investigated the potential of tick gut and salivary gland proteins for use in an anti-tick vaccine; and realized that Uganda might be in urgent need of an anti-tick vaccine.

Saimo-Kahwa explains that scientists from the Global South bring knowledge of the local conditions, problems, and solutions to solving a problem inherent to sub-Saharan African landscapes.

“I believe the need for Global South scientists who can solve the region’s own health issues has never been more pressing, a fact never more evident than during the COVID-19 pandemic,” she says, “I believe many African countries, including Uganda learnt the lessons from that period; Uganda is for instance doubling down on building domestic capacity not just in vaccine development and production, but in science-led national transformation.”

Searching For A Vaccine To A Devastating Parasite

Meanwhile, the hunt for vaccines to a different disease spread by beasts of burden in the Global South is underway.

Amanda Elyssa Ruiz, a PhD student at Brown University in the United States and a Howard Hughes Medical Institute (HHMI) Gilliam Fellow, is looking for potential vaccines to protect against schistosomiasis, a disease that impacts over 250 million people every year, making it the second most socio-economically devastating parasitic disease after malaria.

In countries where schistosomiasis is found, water buffalo are the key labor force for wetland rice agriculture, as well as the main way that humans get infected, so finding a vaccine that protects both would be a big step forward.

“My main project is to identify novel vaccine candidates for schistosomiasis using epidemiologic data alongside immunologic and biochemical approaches,” she says, “The Kurtis lab has developed a screening strategy for vaccine candidates which identifies the antigens on the parasite, Schistosoma japonicum.”