Potential for Co-Infection of a Mosquito-Specific Flavivirus, Nhumirim Virus, to Block West Nile Virus Transmission in Mosquitoes

Fil: Goenaga, Silvina. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Virales Humanas; Argentina.Fil: Kenney, Joan L. Centers for Disease Control and Prevention. Division of Vector-Borne Diseases, Fort Collins, Colorado; Estados Unidos.Fil: Duggal, Nisha K. Centers for Disease Control and Prevention. Division of Vector-Borne Diseases, Fort Collins, Colorado; Estados Unidos.Fil: Delorey, Mark. Centers for Disease Control and Prevention. Division of Vector-Borne Diseases, Fort Collins, Colorado; Estados Unidos.Fil: Ebel, Gregory D. Colorado State University. Immunology and Pathology. Department of Microbiology, Fort Collins, Colorado; Estados Unidos.Fil: Zhang, Bo. Chinese Academy of Sciences. Wuhan Institute of Virology, Wuhan, Hubei; China.Fil: Levis, Silvana C. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Virales Humanas; Argentina.Fil: Enria, Delia A. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Virales Humanas; Argentina. Chinese Academy of Sciences. Wuhan Institute of Virology, Wuhan, Hubei; China.Fil: Brault, Aaron C. Centers for Disease Control and Prevention. Division of Vector-Borne Diseases, Fort Collins, Colorado; Estados Unidos.Nhumirim virus (NHUV) is an insect-specific virus that phylogenetically affiliates with dual-host mosquito-borne flaviviruses. Previous in vitro co-infection experiments demonstrated prior or concurrent infection of Aedes albopictus C6/36 mosquito cells with NHUV resulted in a 10,000-fold reduction in viral production of West Nile virus (WNV). This interference between WNV and NHUV was observed herein in an additional Ae. albopictus mosquito cell line, C7-10. A WNV 2K peptide (V9M) mutant capable of superinfection with a pre-established WNV infection demonstrated a comparable level of interference from NHUV as the parental WNV strain in C6/36 and C7-10 cells. Culex quinquefasciatus and Culex pipiens mosquitoes intrathoracically inoculated with NHUVandWNV, or solely withWNVas a control, were allowed to extrinsically incubate the viruses up to nine and 14 days, respectively, and transmissibility and replication of WNV was determined. The proportion of Cx. quinquefasciatus mosquitoes capable of transmitting WNV was significantly lower for the WNV/NHUV group than the WNV control at seven and nine days post inoculation (dpi), while no differences were observed in the Cx. pipiens inoculation group. By dpi nine, a 40% reduction in transmissibility in mosquitoes from the dual inoculation group was observed compared to the WNV-only control. These data indicate the potential that infection of some Culex spp. vectors with NHUV could serve as a barrier for efficient transmissibility of flaviviruses associated with human disease