Chikungunya is a disease caused by a virus that is transmitted to humans through the bite of infected mosquitoes, and the continents most affected are Africa, Asia and America. At the moment there are no vaccines on the market, nor specific treatments for the treatment of this disease, which mainly causes fever and severe joint pain. However, what could become the first vaccine against this virus is being studied, and which has shown promising results during one phase two clinical trial: Participants who received two doses of vaccine 28 days apart developed good levels of antigen-specific antibodies, which remained in circulation for up to six months.
Chikungunya, maybe we’re close to a vaccine
by Valentina Guglielmo
What we know about chikungunya
This disease was first recognized in 1952 during an epidemic in Tanzania. It is caused by an RNA virus belonging to the genus of alphavirus and to the family of togaviridae. Symptoms related to chikungunya can easily be mistaken for those caused by other viruses such as Zika and Dengue virus. The World Health Organization (WHO) reports officially over 2 million cases since 2005, but points out that the number of people affected worldwide is probably underreported.
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The word “chikungunya” means “writhe” in Kimakonde (the language spoken by an ethnic group in southern Tanzania), and derives from the fact that those affected tend to assume a stooped position due to the joint pains that the disease causes. Other symptoms are fever, body aches, headache, chronic fatigue, nausea and skin rashes, which usually appear within 4-7 days following the bite of an infected mosquito. Usually, the disease resolves itself within a few days, but in rare cases, joint pain can persist for several months or even years. Chikungunya rarely causes serious or fatal complications, but it can be a cause of death in older people.
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Positive (preliminary) results
The formulation currently under study has been called PXVX0317: it is a vaccine based on viral-like particles that mimic the external protein structure of the virus. According to preliminary results, the vaccine (administered in two doses 28 days apart) was able to generate high levels of specific antibodies in the 20 participants involved. The antibodies remained in circulation up to 6 months after vaccination.
The research team that conducted the study also generated monoclonal antibodies from B lymphocytes taken from the blood of three of the vaccinated people. B lymphocytes are among the main protagonists of our immune system, given that they are capable of producing antibodies against specific antigens, such as a specific protein present on the external surface of a virus or bacterium. Some of the monoclonal antibodies thus obtained were effective in protecting laboratory mice from chikungunya, as well as from some related viruses, such as Mayaro and Ross River, also transmitted through the bite of infected mosquitoes and belonging to the same family.
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