Carbohydrate Capped Viral Proteins May Help Develop Malarial Vaccines

Malarial parasites have ability to tag proteins with carbohydrates in order to infect human and mosquito hosts, reveals a study.

Highlights:

Carbohydrate tags attached to viral proteins that help in disease transmission.
These tags are key to successful liver infection and transmission of parasite from host to another secondary vector (mosquito)
The new discovery is of great interest for its implications on improving malarial vaccine design and efficacy.

Although 200 million people are affected with malaria every year and 6,50,000 die as a result, there is no treatment or prevention measure that has higher odds. The first malarial vaccine RTS,S was approved in 2015 and does not offer required protection. The reason being that the malarial parasites are shape-changers and evade immune detection. A research team at the Walter and Eliza Hall Institute has shown for the first time that carbohydrates on the surface of malarial parasites play a vital role in its ability to infect mosquitoes and humans. The study was published in Nature Communications.

Africa to Get World's First Malaria Vaccine
Three African countries will receive the world's first malarial vaccine that has the potential to save thousands of lives from the malarial parasite.

‘Interfering with the parasites ability to add carbohydrate tags, hinders liver infection and transmission to another vector.’

Role of Carbohydrate Tags in Malarial Infection

Two steps in the malaria parasites life cycle are crucial. One is the early stage of human infection, where the parasite invades the liver of the host. The other is the later stage, where the parasite is transferred to another mosquito from the human.

Study shows that the parasite tags its proteins with carbohydrates to stabilize them and evade detection by the host immune system.

Malaria - Overview
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.

How does the New Finding Help Vaccine Design?

Despite decades of intensive research, there is no commercially available vaccine against malaria. The only existing vaccine is the RTS,S that was approved in 2015 against the most deadliest malarial parasite, P.falciparum.

Currently vaccines are made by targeting the viral coat proteins of the parasite. Upon vaccination, our body develops antibodies against the viral proteins. If the vaccinated person is infected with the same virus at a later point, the antibodies kill the parasite stopping infection.

The currently available malarial vaccine, RTS,S is only marginally efficient. One reason could be the fact that the until now the carbohydrate tags over the viral proteins weren’t taken into consideration during vaccine design.

"Now that we know how important these carbohydrates are to the parasite, we can be confident that the malaria parasite cannot ’escape’ vaccination pressure by doing away with its carbohydrates." Dr Goddard-Borger, coauthor of the study, said.

"Interfering with the parasite’s ability to attach these carbohydrates to its proteins hinders liver infection and transmission to the mosquito, and weakens the parasite to the point that it cannot survive in the host." Dr Boddey, lead author of the study, said.

Malaria - Protection Strategies
Malaria is a dangerous disease with lethal consequences that requires protective measures for prevention and control of malaria in endemic regions of the world.

What Causes Malaria?

Malaria is caused by Plasmodium parasites. These accumulate and spread to people through an infected female mosquitoes. These mosquitoes are called the malarial vectors since they carry the parasite and transmit it to people through bites. Out of the 5 malarial species that cause malaria in humans, P. falciparum and P. Vivax pose the greatest risk.

P. falciparum: most prevalent on the African continent, responsible for most malaria-related deaths globally.
P. vivax: dominant malaria parasite in most countries outside of the sub-Saharan Africa.

Reference:

Malaria - (http://www.who.int/mediacentre/factsheets/fs094/en/)

Source-Medindia

Quiz on Malaria
Malaria is a common parasitic disease of the tropics, resulting in a million deaths every year. It is most commonly found in tropical countries. The symptoms of malaria include fever with chills, headache, muscle aches, tiredness, nausea, vomiting, and diarrhea. Malaria fatalities can be reduced if they are detected early and treated appropriately