Arboviruses – viruses transmitted by insects such as mosquitoes – pose a considerable threat to both human and animal health. Despite that, not enough is known about the complex interactions between the virus and the host, particularly in the early stages of infection.

Now, research led by the University of Glasgow has discovered how arboviruses are able to suppress the immune system responses in the initial stages of infection. The findings are published today in Proceedings of the National Academy of Sciences (PNAS).

The team used the Bluetongue Virus (BTV) – a disease which, though not a threat to humans can be devastating in sheep and other ruminants – to reveal how an arbovirus first interacts with its host after initial infection. The research found that BTV subverted the host's immune system by inducing a temporary immunosuppression (suppression of the immune system's natural response) resulting in a delayed antibody production.

The study reveals that BTV enters the animal's system through the skin via a midge bite, and then travels to the lymph nodes where it begins to suppress the natural immune system response. Researchers found that the virus disrupts key cells, known as follicular dendritic cells, that play a vital role in triggering the immune response of the host.

Data from the study also indicated that the severity of the virus's suppression of the immune system was correlated with the clinical outcome from infection.
The first author, said: "This is the first time that we have learned about the novel methods that Bluetongue virus employs to evade the immune system of its host. Significantly, this knowledge can help to understand how other arboviruses of humans induce disease."

http://www.gla.ac.uk/news/headline_486785_en.html