Chikungunya virus (CHIKV), Semliki Forest virus (SFV), and Ross Rivers virus (RRV) are arthropod-borne alphaviruses transmitted by the Aedes mosquitoes. CHIKV has especially become a health burden in South America, with more than 1 million cases reported (PAHO, 2017), and Asia where it is prevalent. Due to its proximity with Asia, CHIKV is now threating to settle in Australia. Currently, no effective vaccine or antiviral treatment are available, however control strategies such as superinfection exclusion are among the methods considered to limit and prevent transmission of arboviruses. Superinfection exclusion is the cellular phenomenon whereby a primary viral infection can prevent replication of a second similar or closely related virus. This phenomenon has been observed for many years in plants, insects, and mammalian cells, but little is still known about the mechanism.
In this study, we characterise superinfection exclusion using alphaviruses with reporter genes in vitro in Aedes Albopictus U4.4 and C6/36 cell lines and in vivo in Aedes aegypti mosquitoes. Our initial results suggested that a primary alphavirus infection in mosquito cell lines, as well as in mosquitoes can dramatically reduce the viral expression of a secondary alphavirus. Our results also suggest that superinfection exclusion relies on virus phylogeny and viral replication to occur. Furthermore, we observed that the mosquito’s immune system plays an important role in this process, however other cellular and viral factors may be involved.
Understanding the underlying mechanism of superinfection will improve our current mosquito viral control strategies. This will enable future development of new arbovirus control strategies to help reduce the burden of mosquito-transmitted diseases in human and livestock populations.