Dr. Bart Gorgoglione

Program overview

Detecting CyHV-3 and CEV in invasive Asian carp species from the Illinois River

Santosh Lamichhane 1, Puntanat Tattiyapong 1,2, Justin Widloe 3, Cahya K. Fusianto 1, Bartolomeo Gorgoglione 1

1 Fish Pathobiology and Immunology Laboratory, Dept. Pathobiology and Diagnostic Investigation / Dept. Fisheries and Wildlife, Michigan State University, East Lansing, MI; 2 Department of Veterinary Microbiology and Immunology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand; 3 Illinois Department of Natural Resources, Yorkville, IL

Invasive Asian carp species, such as Silver (Hypophthalmichthys molitrix), Bighead (H. nobilis), Grass (Ctenopharyngodon idella), and Black Carp (Mylopharyngodon piceus), present substantial ecological and economic risks to the Great Lakes region. These species can serve as reservoirs of pathogens, posing a threat to the health of native fish populations. Notably, Cyprinid herpesvirus 3 (CyHV-3, also known as Koi herpesvirus) and Carp edema virus (CEV) have caused seasonal disease outbreaks and mortality in wild and farmed Common carp (Cyprinus carpio) and Koi (Cyprinus rubrofuscus) worldwide. Despite their virulence in other regions, the effects of these pathogens on invasive and native fish species in the Great Lakes remain largely unknown. To investigate the occurrence of CyHV-3 and CEV, opportunistically sampling was conducted during the invasive Asian carp mass removal campaigns in the Illinois River in summers of 2021 and 2023. A panel of organs (including gills, head kidney, spleen, and liver) were collected and was used for molecular detection, virology (excluding liver), and histology. Both pathogens were detected in native species such as Freshwater Drum (Aplodinotus grunniens), Smallmouth Buffalo (Ictiobus bubalus), and Bigmouth Buffalo (Ictiobus cyprinellus), as well as in invasive Bighead and Silver Carp. Three Smallmouth Buffalo and one Freshwater Drum were found co-infected with both CEV and CyHV-3. Positive samples underwent amplicon sequencing for detection confirmation and genotyping. Sequence analysis classified the CEV strains into Genogroup II and the CyHV-3 strain into the European genotype. Supernatants from pooled homogenized tissues (including gills, kidney, and spleen) were filtered and inoculated onto conventional cell lines such as Common Carp Brain (CCB) and Koi Fin (KF-1), as well as into our newly established Grass Carp fin (GRC-F) cell line. Virus isolation was unsuccessful after 14 days of incubation at 25°C and subculturing. This study represents the first report of CyHV-3 and CEV detection in invasive Asian carp species in the Great Lakes region. Additionally, it is the first detection of these viruses in Freshwater Drum, Smallmouth Buffalo, and Bigmouth Buffalo, and provides preliminary evidence of viral co-infection. Given that the sampled fish were asymptomatic and there was a lack of cytopathic effect in cell culture, along with the unsuccessful amplification of CyHV-3 mRNA, these findings suggest that the viruses may be in a latent or inactive stage.