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By Matt Goss
MELBOURNE, Sept. 28 (Xinhua) -- A cell type native to the liver that could hold the key to defeating malaria in its earliest stage has been discovered, an Australian scientist told Xinhua on Wednesday.
The research, undertaken by the University of Melbourne, found a new type of immune memory T cell that protects the liver from malaria, preventing the infection from reaching the bloodstream.
Daniel Fernandez-Ruiz, a member of the research team from the Peter Doherty Institute for Infection and Immunity, said a vaccine the team had developed to boost the numbers of the memory cell had been successful in trials.
"So what happens is the (malaria) parasites go straight to the liver when they first infect people and it's just very hard to get protection against that infection because the parasites stay there for a short period of time," Fernandez-Ruiz told Xinhua.
"But we have found that there is an immune cell type that is able to kill those parasites in the liver," said Fernandez-Ruiz.
"Once we knew that those cells were able to protect against malaria, we decided to design a vaccination strategy to produce very high numbers of those memory cells," he added.
What happened was that vaccination strategy was trialed in mice against an infection. It was very effective, it protected all the mice that we challenged, he told Xinhua.
Fernandez-Ruiz said that while the immune cells that have been known to researchers for a long time circulate around the body the new cell remains in the liver, making it ideal to fight liver-stage malaria, the earliest stage of the lethal disease.
"Traditionally, memory T cells circulate so they're always patrolling in the gland, circulating around the body and patrolling looking for pathogens," he said.
"Our liver resident memory cells are different in that they don't circulate. They form in organs, in this case in the liver, and they stay there.
"Because malaria parasites only stay in the liver for a short period of time, these cells that are already there are in the right place to fight the parasites straight away whereas the traditionally known circulating memory cells need to be recruited to the liver and that takes time and that's why they're inefficient at protecting against malaria and that's why our vaccination works better."
While the trials with mice have been promising the real test of the new vaccination will be if it proves effective in people in an endemic area.
"Vaccines that seem to work in westerners don't work that well in people living in endemic areas because there are other things that are involved such as other infections," Ruiz-Fernandez said.
"It's much easier to get a good immune response in westerners."
The ramifications of the Melbourne research are potentially enormous. Malaria, a mosquito-borne virus prevalent in the tropics, killed approximately 438,000 people in 2015, down from 839,000 in 2000, a vast majority of which were in the poorest regions of Africa.
