Mosquito Spit Molecule a Potential for Novel Vaccination Against Dengue, Yellow Fever, and Zika

Researchers have just been able to identify a molecule in mosquito spit that can potentially be a novel target for vaccines against a variety of diseases that currently have no protection or medicine.

Mosquito Spit Molecule Could be the New Target for Novel Vaccines

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A team of researchers from the University of Leeds Virus Host Interaction has just discovered a molecule known as sialokinin, making it easier for various viruses to pass from mosquitoes to their human hosts, where they take hold, leading to potentially deadly diseases. These viruses include Yellow Fever, known to cause serious illnesses in roughly 15% of people infected with dengue, which can develop into the fatal diseases dengue fever, and Zika, which caused the 2016 global medical emergency, reports EurekAlert.

Previous studies have determined that the molecule sialokinin could alter the function of blood vessel cells grown in vitro, allowing increased blood flow and effective feeding for mosquitos. However, experts at the time were unaware of the molecule's role in helping viruses infect the body.

In a study published in the journal Proceedings of the National Academy of Sciences of the United States of America, titled "Mosquito saliva enhances virus infection through sialokinin-dependent vascular leakage," researchers observed the behavior of the molecule on skin cells harvested from mice models, discovering that sialokinin causes blood vessels to become permeable which allows contents to leak out into the host's skin inadvertently helping viruses infect the host.

Dr. Clive McKimmie, research supervisor and Associate Professor in the School of Medicine of the University of Leeds, says that the team was able to identify sialokinin as a vital component within the mosquito spit that worsen infection in mammal hosts. He adds that the research suggests blocking the molecule, for example, via a vaccine or topical treatment, which may be a novel approach that prevents severe disease following infection with various distinct viruses.

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Mosquito-Borne Viruses

Dr. Daniella Lefteri, lead author and a Ph.D. researcher at the School of Medicine, says that the findings also explain why some mosquitos spread the infection to humans while others cannot. Anopheles mosquitoes are unable to spread most viruses. Crucially, the study shows that the mosquitos' saliva, which cannot cause leaky blood vessels, cannot enhance virus infection in a mammalian host if it does not contain sialokinin.

Arboviruses are viruses spread by mosquitoes. They affect humans and other mammalian species like cattle. In human hosts, symptoms typically occur three to fifteen days after exposure, lasting up to four days or more. The most common symptoms of these diseases include debilitating fever and headaches.

According to the World Health Organisation, roughly 5.2 million people contracted dengue in 2019, with half of the global population at risk of infection. On the other hand, Yellow Fever infects people that visit or live in parts of South America and Africa with symptoms including muscle aches, with 15% of cases developing into serious illnesses that can be fatal.