Arboviruses (e.g. WNV, DENV, JEV, YFV, etc.) and the diseases they cause are major public health problems in regions of the world where they occur. The two most used methods to control these diseases are vaccination and application of pesticides. Vaccines, if available, are effective in controlling human disease, but do not eliminate the pathogenic arboviruses because most arboviruses are maintained in zoonotic cycles independent of humans. The application of pesticides is designed to reduce the density of a vector population, diminishing the level of virus transmission and indirectly reducing the incidence of infection and illness. But like vaccines, pesticides must be applied indefinitely, or the vectors and their associated diseases will reemerge. Heavy application of pesticides can be beneficial during epidemics but is not sustainable long-term because of the cost, public opposition, environmental toxicity and the development of resistance by the target vectors.
Recently, a third control option has been considered; manipulation of the insect microbiome to reduce the vector competence of mosquitoes for selected arbovirus pathogens. During the past 4 years the laboratory has identified and characterized two new taxa of mosquito specific viruses (MSVs), as well as several others within established taxa that include arboviruses, including flaviviruses. Mosquito-specific flaviviruses (MSFs) belong in two distinct clades within the genus flavivirus. One is phylogenetically distinct from the main flavivirus group that includes vertebrate arboviral pathogens (tick- and mosquito-borne). This clade includes MSFs such as cell fusing agent (CFAV), Culex flavivirus (CxFV), Aedes flavivirus (AeFV), Kamiti River (KRV), Quang Binh (QBV), and Nakiwogo (NAKV) virus. The second clade falls within the mosquito-borne clade of flavivirus pathogens and is closely related to medically important viruses such as WNV, DENV and YFV. This MSV clade includes Aripo (ARPV), Nounane (NANV), Nhumirim (NHUV), Donggang (DGV), Long Pine Key (LPKV), marisma (MMV) and other viruses.
Using LPKV and MMV as models the laboratory is currently exploring methods to create a population of mosquitoes that is infected with LKPV with reduced capacity to transmit human pathogenic arboviruses. The factors that determine the narrow host range of mosquito-specific viruses (using LKPV and MMV as models) are poorly understood and mechanisms such as attachment and entry, incompatibility with host cell factors, or temperature sensitivity have been suggested. Gaining insights into the elements that determine this host range will improve our understanding of MSF-vector interactions and evolution, and this knowledge can be leveraged to manipulate specific natural viral symbionts in mosquitoes, such as LPKV, to reduce their ability to transmit arboviral pathogens of public health importance.