The First Isolation of Insect-Specific Alphavirus (Agua Salud alphavirus) in Culex (Melanoconion) Mosquitoes in the Brazilian Amazon

Abstract

Advances in diagnostic techniques coupled with ongoing environmental changes have resulted in intensified surveillance and monitoring of arbovirus circulation in the Amazon. This increased effort has resulted in increased detection of insect-specific viruses among hematophagous arthropods collected in the field. This study aimed to document the first isolation of Agua Salud alphavirus in mosquitoes collected within the Brazilian Amazon. Arthropods belonging to the family Culicidae were collected within a forest fragment located in the Environmental Protection Area of the metropolitan region of Belem. Subsequently, these specimens were meticulously identified to the species level. Afterward, the collected batches were macerated, and the resulting supernatant was then inoculated into C6/36 and Vero cell cultures to facilitate viral isolation. The presence of arboviruses within the inoculated cell cultures was determined through indirect immunofluorescence analysis. Furthermore, positive supernatant samples underwent nucleotide sequencing to precisely identify the viral strains present. Notably, a batch containing Culex (Melanoconion) mosquitoes was identified to be positive for the genus Alphavirus via indirect immunofluorescence. This study is the first report on insect-specific alphavirus isolation in Brazil and the first-ever description of Agua Salud alphavirus isolation within Amazon Forest remnants.