A novel Dicistro-like virus discovered in Procambarus clarkii with "Black May" disease
Pengdan Huang1, Guoqing Shen1, Jie Gong1
1Wuxi Fisheries College, Nanjing Agricultural University, Nanjing, China.
Abstract:
The peak period of morbidity and death in cultured Procambarus clarkii is around May each year and is called the "Black May" disease. The pathogen causing "Black May" disease is believed to be a white spot syndrome virus (WSSV). In 2018, a significant number of P. clarkii died in the pond culture of Xinglong Township, Xuyi County. Two sampling tests on the affected pond showed that, in addition to WSSV, a novel Dicistro-like virus (PcDV) was present. Genomic sequence analysis indicated that this new virus belongs to the Dicistroviridae family, Picornaviridaes order. A high number of spherical particles were detected in gill tissues of P. clarkii with "Black May" disease by electron microscopy, a finding consistent with viruses from the Picornaviridaes order. From October 2018 to September 2019, we took monthly samples from Hubei, Jiangsu and Anhui provinces, and tested for the presence of PcDV and WSSV in P. clarkii. The detection rates of PcDV in P. clarkii peaked from April to June, consistent with the onset of the "Black May" disease. In conclusion, we believe that the discovery of PcDV will provide new research directions for investigating the pathogens causing "Black May" disease in P. clarkii.
Insights
A novel Dicistro-like virus (PcDV) was identified in Procambarus clarkii suffering from "Black May" disease. This discovery offers new insights into the viral pathogens responsible for this significant crayfish mortality event.
Area of Science:
- Aquatic animal health
- Virology
- Crustacean aquaculture
Background:
- The "Black May" disease causes significant mortality in cultured Procambarus clarkii annually.
- White spot syndrome virus (WSSV) was previously suspected as the primary pathogen.
- A severe outbreak in 2018 prompted further investigation into causative agents.
Purpose of the Study:
- To identify novel viral pathogens associated with "Black May" disease in Procambarus clarkii.
- To characterize the newly discovered virus and determine its prevalence.
- To explore the role of the new virus in "Black May" disease outbreaks.
Main Methods:
- Virus isolation and genomic sequencing.
- Electron microscopy of infected tissues.
- Monthly sampling and molecular detection (PCR) for viruses in crayfish populations across multiple provinces.
Main Results:
- A novel Dicistro-like virus (PcDV), belonging to the Dicistroviridae family, was identified alongside WSSV in affected crayfish.
- Electron microscopy revealed spherical particles consistent with Picornaviridaes in infected gill tissues.
- PcDV detection rates peaked from April to June, coinciding with the "Black May" disease season.
Conclusions:
- The discovery of PcDV provides a new potential pathogen for "Black May" disease.
- PcDV prevalence correlates with the seasonal onset of the disease.
- Further research into PcDV is crucial for understanding and managing "Black May" disease in Procambarus clarkii.
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