Bites from mosquitoes that spread viruses trigger a distinct immune response in the skin after they bite, which increases the severity of infection caused by the transmitted virus.
Clive McKimmie at the University of Leeds, UK, and his colleagues injected mice with one of two mosquito-borne viruses. Mice that were bitten by virus-free mosquitoes and then injected with the microbe showed an immune response that retained more virus at infection sites than did infected mice that had not been bitten. Immune cells called neutrophils were drawn to the bite, where they enhanced the virus's ability to infect and multiply, causing more-severe disease.
Blocking certain immune cells from reaching the site of an insect bite reduces viral replication and could be a way to diminish disease after a bite, the authors say.