Twin Cities WRS Seminar

Carp Killing Viruses Reach Minnesota! Could it be a Window of Opportunity?


Isaiah Tolo
Graduate Student, Conservation Sciences

March 15, 2019


Common carp (Cyprinus carpio) is a widely cultivated fish species worldwide and an ecologically destructive invasive species in Minnesota. Koi herpesvirus (KHV), also called Cyprinid herpesvirus 3 (CyHV-3), and Carp edema virus (CEV) are highly specific and virulent pathogens of common and koi carp in wild and farmed populations around the world. During the summers of 2017 and 2018, multiple mass mortalities of common carp were reported in three states in the USA, the majority of which were widely distributed across eight major watersheds in MN. Additional mortality events in Wisconsin, Pennsylvania, and in occurred during this time period. Samples from these events and from five apparently healthy carp populations were screened for KHV, CEV, and SVCV using polymerase chain reaction (PCR) and real time polymerase chain
reaction (qPCR). KHV was detected in 13 events, CEV in two events and coinfections in four events. Sequence analysis revealed that KHV and CEV are closely related to European lineages of these viruses. This represents the first detection of coinfections of KHV and CEV in wild populations in the USA as well as the first detection of KHV in wild fish in MN and PA. These findings are part of a larger project which seeks to identify pathogens that are useful in the management of invasive species.