Thursday February 21, 2019
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An Experimental Vaccine to Treat Malaria

Scientists hope to get a better grasp on the system these vaccines employ, known as cellular immunity. Harnessing this system could help tackle hepatitis and HIV infection.

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Vaccines
A doctor assists people looking for treatment for malaria at a health center in San Felix, Venezuela. VOA

After decades of disappointment in efforts to develop a malaria vaccine, researchers are starting to see promise in a new approach.

While most vaccines trigger the body’s defenses to produce antibodies against a disease-causing germ, the new approach recruits an entirely different branch of the immune system.

If it works, it could open up a new route to attack other diseases, including hepatitis and possibly HIV, the virus that causes AIDS.

Nearly 450,000 people die of malaria each year, according to the World Health Organization. The parasites that cause the disease are increasingly becoming drug-resistant.

One successful vaccine has been developed so far, but it prevented only about a third of cases in a clinical study.

Experts have decided that’s better than nothing. The vaccine is being piloted in Ghana, Kenya and Malawi.

Vaccine
Defensive cells killed liver cells that were infected with malaria parasites. (VOA)

New angle

Other scientists are trying a different angle of attack.

There are basically two ways to prevent germs from causing infections. “You either prevent them from getting into cells with antibodies, or you kill them inside the cells with T-cells,” said Stephen Hoffman, chief executive officer of Sanaria, a company working on one vaccine.

Most vaccines target the infection by building up antibodies. “If you need to kill them inside the cells with T-cells, we haven’t been overwhelmingly successful,” Hoffman said.

But Sanaria is one group seeing success by targeting malaria parasites inside infected liver cells, the first stop in the complex life cycle of the disease.

One key difference is how the vaccine is delivered. Hoffman’s group tried a typical route: injecting radiation-weakened parasites into patients’ skin or muscle. That didn’t work.

But it did work when injected directly into veins.

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A public health worker takes a blood sample from a woman to be tested for malaria in Bo Rai district, Trat province, Thailand. VOA

The weakened parasites traveled to the liver, where they set off an immune reaction. Defensive cells killed liver cells that were infected with malaria parasites.

And the liver’s defenses were ready when faced with the real thing months later.

Most of that early work has been done in mice and macaques. When Hoffman and colleagues did something similar with a handful of human patients, most were protected against infection.

No waiting

Recruiting immune cells in the liver is especially effective because “we don’t need to wait until the immune system figures out that the parasite is in the liver and starts mounting an immune response, which can take days and sometimes weeks,” said Adrian Hill, director of the Jenner Institute at Oxford University.

“By then, the malaria’s gone. It only spends a week in the liver, and then it’s out in your blood causing disease.”

Vaccine
FILE – A worker of the Ministry of Public Health and Population fumigates in the street against mosquito breeding to prevent diseases such as malaria, dengue and Zika in Port-au-Prince, Haiti, Feb. 15, 2016. VOA

Hill’s group just published a study in the journal Science Translational Medicinein which immune cells in the liver were triggered by using a protein from the parasite, rather than the entire organism.

Scientists hope to get a better grasp on the system these vaccines employ, known as cellular immunity. Harnessing this system could help tackle hepatitis and HIV infection.

Also Read: Alcohol Kills More People Than AIDS, Violence Combines: WHO

Drugs can control HIV infection but can’t eliminate it from the body.

“If somebody could get cellular immunity to work really well for vaccination, that would be transformative for a whole range of diseases,” Hill said. “Not just for infectious diseases that we want to prevent, but ones that we want to treat and we can’t treat today.” (VOA)

Next Story

Know How Higher Intake of Sodium Can Treat Lightheadedness

Greater sodium intake is widely viewed as an intervention for preventing lightheadedness when moving from seated to standing positions.

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sodium
"Health practitioners initiating sodium interventions for orthostatic symptoms now have some evidence that sodium might actually worsen symptoms," Juraschek said. Pixabay

Higher sodium intake should not be used as a treatment for lightheadedness, say researchers challenging current guidelines for sodium consumption.

Lightheadedness while standing, known as postural lightheadedness, results from gravitational drop in blood pressure and is common among adults.

Greater sodium intake is widely viewed as an intervention for preventing lightheadedness when moving from seated to standing positions.

However, contrary to this recommendation, researchers at Beth Israel Deaconess Medical Centre (BIDMC) found that higher sodium intake, actually increases dizziness.

“Our study has clinical and research implications,” said Stephen Juraschek, researcher from BIDMC in Boston.

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Greater sodium intake is widely viewed as an intervention for preventing lightheadedness when moving from seated to standing positions. Pixabay

“Our results serve to caution health practitioners against recommending increased sodium intake as a universal treatment for lightheadedness. Additionally, our results demonstrate the need for additional research to understand the role of sodium, and more broadly of diet, on lightheadedness,” Juraschek said.

For the study, reported in The Journal of Clinical Hypertension, the team used data from the completed DASH-Sodium trial, a randomised crossover study that looked at the effects of three different sodium levels (1500, 2300, and 3300 mg/d) on participants’ blood pressure for four weeks.

While the trial showed that lower sodium led to decrease in blood pressure, it also suggested that concerns about lower level of sodium causing dizziness may not be scientifically correct.

Also Read: ‘It Has Been A Very Long Process, But Ultimately A Very Successful Process’: South Korea Agrees to Pay More for U.S. Troops

The study also questioned recommendations to use sodium to treat lightheadedness, an intervention that could have negative effects on cardiovascular health.

“Health practitioners initiating sodium interventions for orthostatic symptoms now have some evidence that sodium might actually worsen symptoms,” Juraschek said.

“Clinicians should check on symptoms after initiation and even question the utility of this approach. More importantly, research is needed to understand the effects of sodium on physical function, particularly in older adults.” (IANS)