Isolation and identification of a reovirus strain from Gibel carp

Objective  To discover a new pathogen of Gibel carp (Carassius auratus gibelio), and to provide a theoretical basis for the disease prevention and control.

Method  Gibel carps suspected having hemorrhagic disease were collected from a farm in Jilin Province. Tissues were observed for bacterial infection and parasite contamination. PCR was used to detect Cyprinid herpes virus-2. Artificial infection was conducted, the infection filtrate was vaccinated to the carp epithelial tumor cells (EPC), and the EPC were observed by an electron microscope. The virus genome was analyzed by SDS-PAGE and identified by RT-PCR and sequencing.

Result  Neither bacterial nor parasitic infection was detected. Cyprinid herpes virus-2 specific bands were not detected by PCR. After healthy Gibel carps were infected with tissue filtrate of sick fish, the mortality rate reached 86.7% within seven days. Clear cytopathy was detected after four generations via blind passage. The virus particles were observed by an electron microscope after negative staining, the particle was spherical with around 70 nm in diameter and with no envelope. The virus was initially determined as a reovirus strain (temporarily named JL-4). The SDS-PAGE results showed that JL-4 possessed 11 segments of dsRNA, which was the typical characteristic of Aquareovirus genome. Cluster analysis for the sequences of the RT-PCR amplification product showed that S6 sequences from JL-4 and reovirus HZ08 had 99% similarity, confirming that JL-4 was reovirus.

Conclusion  One reovirus strain was isolated and identified from Gibel carp.