As 'flesh-eating' Leishmania come closer, a vaccine against them does, too

September 13, 2017
The life cycle of Leishmania parasites in flies and humans. If passes through promastigote and amastigote phases as it spreads. Credit: Centers for Disease Control and Prevention / press and educational handout

Parasites that ulcerate the skin, can disfigure the face, and may fatally mutilate its victim's internal organs are creeping closer to the southern edges of the United States.

No vaccine is available against Leishmania yet, but researchers have now come closer to changing that. A new experimental vaccine, made with a proprietary biological particle developed at the Georgia Institute of Technology, has immunized laboratory mice that were genetically altered to mimic the human immune system.

The vaccine exploits a weakness in Leishmania's tricky chemical camouflage, which normally hides it from the victim's disease-fighting cells, to trigger a forceful immune response against the parasite, according to a new study.

Second-deadliest parasite

Leishmania are the second-deadliest in the world, topped only by malaria, according to the World Health Organization. There are some 30 strains of Leishmania.

They are transmitted mainly through the bite of a phlebotomine sand fly, which feeds on blood, and global warming is expanding the insect's potential habitat northward from Latin America. The outbreak regions closest to the United States of leishmaniasis, the disease caused by the parasite, have come within roughly 300 miles of the border.

Some species of phlebotomine sand fly transmit Leishmania parasites. Credit: Parasitology department of the Universidade Federal de Minas Gerais in collaboration with Georgia Tech.

As with many diseases, many people who contract Leishmania, the parasite, may develop leishmaniasis, the disease, with varying symptoms, or perhaps even show outward signs of the disease. But when it breaks out, one form can cause large skin boils, and some infections severely eat away at the nose and lips, even removing parts of them.

If another form of the parasite gets into the bloodstream, it can damage the liver and spleen in a deadly form of the disease called visceral leishmaniasis, also known as black fever.

"If you don't treat it, within 20 to 40 days very often kills the victim," said Alexandre Marques, a professor in the parasitology department of the Universidade Federal de Minas Gerais in Brazil, and one of the lead researchers on the new experimental vaccine. Conventional treatment, though mostly effective, can leave behind small numbers of the parasite, which can lead the patient to relapse or act as a carrier, in a similar manner as malaria.

A vaccine could be better at halting or averting outbreaks.

Long-awaited vaccine

Leishmania, which are single-cell organisms about the size of large bacteria, have been a scourge in about 90 countries in South America, Africa, the Middle East, Asia and southern Europe. For decades, researchers have worked to find a vaccine against them and similar parasites without success.

A typical boil caused by leishmaniasis. These can spread across the body if left untreated. A form of the disease called mucosal leishmaniasis can viciously infect tissues in the lips and nose, even partially removing them. Credit: Parasitology department of the Universidade Federal de Minas Gerais in collaboration with Georgia Tech

"In comparison to viruses and bacteria, these are much more complex organisms and more difficult to crack," said M. G. Finn, who also led work on the new vaccine. Finn is a professor in Georgia Tech's School of Biological Sciences and in the School of Chemistry and Biochemistry, which he also chairs.

The new vaccine leverages intimate knowledge that Marques's team has gained living and working on the edge of leishmaniasis outbreak regions. "Alex's (Marques's) students collect the sand flies, then they extract the parasites in the lab and do complex mass spectrometry and other tests to study their molecular makeup in impressive detail," Finn said.

The team has uncovered minute details on the outer surface of Leishmania that make it vulnerable to a human immune reaction. The potential new , invented at Georgia Tech, employs a fake virus as bait to attract major immune system forces to these weaknesses to attack them.

The fake virus, or virus-like particle, is not infectious, and the body destroys it after use. Finn's lab has developed many variations of such particles in recent years, and other products containing it have already been through phase II human clinical trials.

Marques and Finn published the results of their vaccination development and testing on September 13, 2017, in the journal ACS Central Science. The research was funded by the National Institutes of Health, Children's Healthcare of Atlanta, and Brazil's National Council for Scientific and Technological Development.

Explore further: Scientists reveal structure of potential leishmaniasis vaccine

More information: ACS Central Science (2017). DOI: 10.1021/acscentsci.7b00311

Related Stories

Scientists reveal structure of potential leishmaniasis vaccine

March 9, 2017
Leishmaniasis, caused by the bite of a sand fly carrying a Leishmania parasite, infects around a million people a year around the world. Now, making progress toward a vaccine against the parasitic disease, researchers reporting ...

How the leishmania parasite sabotages the immune response

October 12, 2016
An international collaborative of researchers has identified a mechanism that allows the leishmania parasite, which causes leishmaniasis, to evade the immune system and thereby produce infection. The study, published in Immunity, ...

Meeting a microbe in the morning or in the evening: Is it all the same?

September 8, 2017
Does the time of day matter when our body is infected by a parasite? According to new research from McGill University, it matters a great deal.

Study reveals the role of sex in spread of deadly disease

January 16, 2014
Research involving scientists at the University of York has provided important new information about transmission of human leishmaniasis, a group of infectious diseases which kills more than 100,000 people a year.

The human parasite Leishmania is a probiotic for the fly that carries it

July 22, 2014
The Leishmania parasite, which causes the human disease leishmaniasis, acts as a probiotic in the insect that transmits it to humans, protecting them from bacterial disease. Findings published in the open access journal Parasites ...

Skin plays significant role in spread of leishmaniasis

July 5, 2017
Scientists at the University of York have discovered that parasites responsible for leishmaniasis - a globally occurring neglected tropical disease spread by sand flies - are mainly acquired from the skin rather than a person's ...

Recommended for you

Anti-malaria drug shows promise as Zika virus treatment

November 17, 2017
A new collaborative study led by researchers at Sanford Burnham Prebys Medical Discovery Institute (SBP) and UC San Diego School of Medicine has found that a medication used to prevent and treat malaria may also be effective ...

Decrease in sunshine, increase in Rickets

November 17, 2017
A University of Toronto student and professor have teamed up to discover that Britain's increasing cloudiness during the summer could be an important reason for the mysterious increase in Rickets among British children over ...

Scientists identify biomarkers that indicate likelihood of survival in infected patients

November 17, 2017
Scientists have identified a set of biomarkers that indicate which patients infected with the Ebola virus are most at risk of dying from the disease.

Research team unlocks secrets of Ebola

November 16, 2017
In a comprehensive and complex molecular study of blood samples from Ebola patients in Sierra Leone, published today (Nov. 16, 2017) in Cell Host and Microbe, a scientific team led by the University of Wisconsin-Madison has ...

Study raises possibility of naturally acquired immunity against Zika virus

November 16, 2017
Birth defects in babies born infected with Zika virus remain a major health concern. Now, scientists suggest the possibility that some women in high-risk Zika regions may already be protected and not know it.

A structural clue to attacking malaria's 'Achilles heel'

November 16, 2017
Researchers from The Scripps Research Institute (TSRI) and PATH's Malaria Vaccine Initiative (MVI) have shed light on how the human immune system recognizes the malaria parasite though investigation of antibodies generated ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.