Surveillance for arthropod-associated viruses in northwestern and southwestern Mexico using traditional virus detection techniques and metagenomics

Abstract

The objectives of this study are to increase our understanding of the arthropod-associated viruses circulating in Mexico by serologically assaying domestic animals for evidence of flavivirus infection and testing mosquitoes and ticks for novel and recognized viruses by virus isolation in cell culture and metagenomics. Sera and arthropods were collected in 2018 and 2019 in the states of Chihuahua and Michoacan in northwestern and southwestern Mexico, respectively. Sera were collected from 648 domestic animals (horses, poultry, sheep, cows, dogs, cats, pigs, and rabbits). A total of 1337 mosquitoes of three genera (Aedes, Culex, and Mansonia) were also collected by manual aspiration. To date, sera from 194 horses have been tested by plaque reduction neutralization test (PRNT) using West Nile virus (WNV) and St. Louis encephalitis virus (SLEV). Of these, 113 (56.7%) horses were seropositive for WNV, three (15.3%) horse was seropositive for SLEV, 11 (5.6%) horses had antibodies to an undetermined flavivirus and 64 (32.6%) horses were negative for antibodies to flaviviruses. The mosquitoes were sorted in 35 pools, homogenized and inoculated onto monolayers of Aedes albopictus (C6/36) and/or Culex tarsalis (CT) cells. A second blind passage was performed then total RNA was extracted and analyzed by RNA-seq. Our metagenomics data are currently being analyzed for viral sequences. However, because 16 homogenates caused cytopathic effect, we consider it likely that viruses have been recovered. Ticks are currently being processed. Taken together, our ongoing serological investigation and virus discovery experiments will increase our understanding of the arthropod-borne viruses present in northwestern and southwestern Mexico.