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Could leishmaniasis vaccine be used to thwart COVID-19?

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Nearly three decades ago, a young surgical intern found himself trying to save the life of a young boy who was brought to his clinic in Mumbai. The boy had been rushed to the emergency room, his body in shock.

“At the time we didn’t know what had happened,” said Abhay Satoskar, MD, PhD, now the vice chair of research for The Ohio State University Wexner Medical Center’s Department of Pathology. “He was just playing at home and bumped against the table or something.”

An autopsy later revealed that the child, no older than 10, had a hugely enlarged spleen. A small bump had been enough to rupture the organ.

“This,” Satoskar said, “was preventable.”

The cause of the boy’s death was a form of leishmaniasis, one of the world’s deadliest parasitic diseases. Since that encounter, Satoskar has dedicated his career to finding a cure.

“With that kind of experience, if I could focus in the area that would not only benefit folks back home, but people worldwide, that makes more sense to me,” he said.

While the advent of climate change and large-scale population displacement are only making the situation more pressing, several positive strides have been made in recent years toward curbing the deadly disease. Satoskar and his team have received several large grants toward developing a human vaccine, which he says is invaluable in curbing the threat of the disease.

“The drugs available right now are not ideal — they are long treatments with a lot of side effects, and we don’t yet have a vaccine,” Satoskar said. “And the sand fly (its carrier) is becoming resistant to DDT. Without a vaccine, you can’t eliminate the disease, no matter how hard you try — that’s the missing component.”

What is leishmaniasis?

A parasitic disease transmitted by the bites of infected phlebotomine sand flies, leishmaniasis is primarily found in some parts of Asia, the tropical region of North Africa, southern Europe and in some parts of the Americas. Worldwide, about 12 million people are infected with some form of the disease.

Its most common form, cutaneous leishmaniasis, leaves festering ulcers and scarring; its visceral form (VL) causes fever, weight loss, enlargement of the liver and spleen, and anemia, according to the World Health Organization. Between 50,000 and 90,000 new cases of VL present each year; when untreated, it is fatal in more than 95% of cases, according to the WHO.

The disease is associated with malnutrition, the movement of large populations of people, changes in regional climate and poverty.

“There have been few resources to develop new drugs, therapies, diagnostics or vaccines, because leishmaniasis is a disease of the poor,” Satoskar said. “There’s not a lot of big pharmas interested; there are not a lot of ways to make money. But about 10% of the world population is at risk of getting infected, which is a huge number.”

Indigenous cases of leishmaniasis have been reported in Texas, according to the Journal of the American Medical Association. In Columbus in 2018, the Wexner Medical Center treated several cases in people who had traveled abroad.

“Especially in America, there are a lot of dogs now infected with leishmaniasis, as dogs are reservoirs for the disease — it’s starting,” Satoskar said. “With climate and ecological changes, vectors (disease carriers) can move up and the environment can be more conducive for their growth. You’ve seen that with Zika; the same thing can happen.”

A vaccine that could attack two problems?

Thanks to his team’s work, however, a usable human vaccine for leishmaniasis is on the horizon — and also could be an important tool in preventing the spread of COVID-19 in the developing world.

Satoskar and his team are developing a single vaccine that could work against the SARS-CoV-2 virus, which causes COVID-19, and leishmaniasis. The approach would lower costs by distributing two vaccines for the price of one and overcome barriers global health leaders have identified as the pandemic moves into developing nations.

“A multi-pathogen vaccine will be more affordable and more easily deployed with a better community acceptance in resource-poor countries,” Satoskar said. 

This new research will engineer the live, weakened leishmaniasis vaccine the team has developed to produce a SARS-CoV-2 protein that triggers the body’s immune system against the virus. Phase 1 clinical trials for the leishmaniasis vaccine begin in 2021-22.

“We could genetically engineer weakened leishmania parasites to make the (SARS-CoV-2) protein,” Satoskar said. “And since these parasites survive in the host for eight to nine months without causing any disease, they will be a long-term and persistent source of viral proteins to immune cells to elicit a strong immune response (against COVID-19). A similar approach can be used for developing vaccines against co-endemic infections.”

How to help

Satoskar said that anyone interested in supporting that progress can make donations to the Global Health Initiatives in Pathology & Microbiology Fund, established through The Ohio State University Foundation. Donations help support all aspects of the mission along with research, he said, including travel, training, supplies and medical outreach.