Surprising Update About Mosquito Saliva: Study Suggests It Can Actually Inhibit Transmission Of Dengue Virus

Months after a study suggested that mosquito saliva can enhance disease severity, another one revealed the opposite. It was previously claimed that the insect's spit can make virus spread faster due to its factors that dampen the immune response of a mammal host; but just recently, it was found that a protein family present in mosquito saliva can actually hinder virus transmission to human cells.

According to Medical News Today, PLOS Neglected Tropical Diseases published a study regarding D7, a protein family contained by Aedes aegypti saliva. The findings show that D7 can bind to Dengue Virus (DENV) and control it. And surprisingly, it is the antibodies against the proteins that may facilitate the transmission of virus and make infections worse. These antibodies are present in humans who are exposed to mosquito bites.

In the recent study, researchers focused on proteins that could possibly inhibit DENV. Batches of proteins were tested to find out if they could enhance or block the transmission of virus to human cells.

Upon analyzing the proteins containing inhibitory function, high levels of D7 were found. Mosquito saliva contains D7 family members, which are thought to assist the process of blood feeding. Moreover, it was found that the levels of D7 were higher in the salivary glands of DENV-infected Aedes mosquitoes compared with those of the uninfected ones.

Further tests suggested that D7 proteins may have the ability to modulate the host cell and at the same time act on the virus to prevent multiplication and infection. It was likewise found that the presence of D7 considerably reduced DENV levels.

Meanwhile, it is important to take note that while D7 proteins have the ability to provoke strong immune responses, humans exposed to mosquitoes have anti-D7 antibodies in high levels. They inhibit the function of D7; hence these antibodies may enhance transmission of the disease despite their ability to hinder a mosquito's efficient blood feeding. Such findings call for the development of more strategies to limit or hinder disease transmission as well as promotion of the development of more therapeutics and vaccines that can block transmission.

In June this year, Science News reported that a mosquito's spit might be worse than its bite. This is due to the claim that mosquito saliva can weaken blood vessels, which make them more permeable. These findings are the opposite of the aforementioned results of a more recent study.