Experimental Malaria Vaccine Found Effective Against Different Strains

Highlights:

A research team from the University of Maryland tested the recently developed malaria vaccine to identify the versatility of the vaccine
64% of the study participants were protected against the parasite used in the vaccine
83% of the study participants were protected against another strain of the parasite, not used in the vaccine

A malaria vaccine which is still in the experimental stage has been found to offer protection against a strain of malaria that is not contained in the vaccine, according to the research team from The University of Maryland School of Medicine (UM SOM) and the National Institutes of Health (NIH)'s National Institute of Allergy and Infectious Diseases (NIAID). This study was published recently in the journal Proceedings of the National Academy of Sciences (PNAS).

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Malaria
Malaria is caused by a parasite that enters blood through the bite of an infected mosquito. It is characterized by fever, vomiting, shivering, sweating and other symptoms.

‘Malaria vaccine effective against multiple strains will help limit spread of the disease’

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This aspect of the study is of great clinical significance as there are bound to be varied strains of malaria in a region that is prone to this disease. A vaccine should not be protective for only one particular strain of a disease but, in order to be useful, it should offer protection against more than one strain. Associate professor of medicine at the UM SOM Center for Vaccine Development, Dr. Kirsten E. Lyke, who is the lead author of the study, said that the versatility shown by the vaccine held promise. The study aided in showing that the vaccine was effective against two strains of malaria. The associate professor who has been working on malaria for more than 10 years says that there is a need for continued research but the results have been fantastic thus far.

PfSPZ Vaccine

This vaccine, developed by Sanaria Inc consists of P. falciparum sporozoites that are lowered in virulence and which do not give rise to the disease. Previous studies conducted on the effectiveness and safety of the vaccine showed that this vaccine was safe to be used. It provided more than a year of protective cover against an African strain of malaria.

Malaria vectors in India
Anopheles philipenensis, Anopheles minimums, Anopheles sundaicus, Anopheles stephenis are key malarial vectors which breed mostly in stagnant water, saline lakes, shallow wells, tea gardens and marshy areas.

Clinical trial

Thirty-one1 healthy adults who were aged between 18 to 45 years were enrolled in the study and they received three doses of the vaccine intravenously spread over a few months. The study was led by Dr. Lyke and Dr. Robert A. Seder, NIAID's Vaccine Research Center (VRC)'s chief of the Cellular Immunology Section.

After a period of 19 weeks from the time of the last dose of the vaccine, the volunteers along with participants who were not vaccinated were exposed to bites from mosquitoes that were infected with the strain of P. falciparum parasites which were used to develop the PfSPZ Vaccine.

The findings of the study showed that

Nine of the 14 participants (64%) who were administered with the PfSPZ Vaccine did not show the presence of the malarial parasite
All six of participants who were not vaccinated had malaria parasites found in their blood.
Among the nine vaccinated participants who did not show the presence of the malarial parasite, six participants were exposed to mosquito bites infected with another P. falciparum strain which was carried out 33 weeks after the last immunization.
Five of the 6 participants (83%) were protected against malarial infection
Participants who were not vaccinated were not protected against the infection.

During the course of the study, the participants who developed malaria were provided with immediate treatment and care. The molecular study of the protection received from the malaria vaccine revealed that the PfSPZ vaccine activated T lymphocytes, which are essential components of the body's defense against an infection.

Further research is aimed at identifying if there are changes that need to be incorporated into the vaccine which will help in improving the protection offered by the vaccine. The next step in the vaccine trial is already underway, with the vaccine being trialed at three different doses among 5 to 12 month old infants in Kenya.

Certain forms of malaria can be treated, however, certain forms like cerebral malaria can lead to damages to the brain which can result in learning disabilities, speech problem and even fatality. A safe and reliable vaccine would aid in protection against this infection, safeguarding people from harm.

Malaria

The malarial parasite is transmitted to humans by the bite of the female mosquito that inject the immature sporozoite. After the initial entry, the parasites travel to the liver where they grow and multiply. After they have multiplied into large numbers, they leave the liver and may break out of blood vessels or block them, preventing blood flow to essential organs.

The symptoms of malaria include fever, chills, vomiting, fatigue and headache. According to statistics provided by the World Health Organization,

In 2015, 212 million people suffered from malaria globally
429,000 people died due to malaria and this included mostly young African children

The most common species of the malarial parasite is Plasmodium falciparum that leads to morbidity and mortality in Africa. In countries like the United States, where malaria is not endemic, tourists who travel to malaria prone areas, especially newly settled immigrants who might go to their home nation and then travel back with the disease, lead to incidences of malaria.

References :

Malaria - (https://www.cdc.gov/malaria/)

Source: Medindia

Quiz on Malaria
Malaria is a common parasitic disease of the tropics, resulting in a million deaths every year. Early detection and adequate treatment at the right time can reduce deaths due to malaria. Test your knowledge on this condition by taking this quiz.