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Investigation on Natural Infection of Covert Mortality Nodavirus in Farmed Giant Freshwater Prawn (Macrobrachium
Jitao Xia1,2, Chong Wang2, Liang Yao1,2
1College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China.
Abstract:
Covert mortality nodavirus (CMNV), from the Nodaviridae family, is characterized by its unique cross-species transmission and wide epidemic distribution features. In this study, Macrobrachium rosenbergii was proved to be infected naturally by CMNV, which further expand the known host range of CMNV. Here, 61.9% (70/113) of the M. rosenbergii samples collected from Jiangsu Province were CMNV positive in the TaqMan RT-qPCR assay, which indicated the high prevalence of CMNV in M. rosenbergii. Meanwhile, the sequences of CMNV RdRp gene cloned from M. rosenbergii were highly identical to that of the original CMNV isolate from Penaeus vannamei. In situ hybridization (ISH) and histology analysis indicated that the intestine, gill, hepatopancreas and ovary were the targeted organs of CMNV infection in M. rosenbergii, and obvious histopathological damage including vacuolation and karyopyknosis were occurred in the above organs. Notably, the presence of CMNV in gonad alerted its potential risk of vertical transmission in M. rosenbergii. Additionally, numerous CMNV-like particles could be observed in tissues of hepatopancreas and gill under transmission electron microscopy. Collectively, our results call for concern of the potential negative impact of the spread and prevalence of CMNV in M. rosenbergii on its aquaculture, as well as providing a renewed orientation for further investigation and exploration of the diverse pathogenic factors causing M. rosenbergii diseases.
Insights
Covert mortality nodavirus (CMNV) infects the giant freshwater prawn, Macrobrachium rosenbergii, expanding its known host range. High prevalence and tissue damage were observed, raising concerns for aquaculture.
Area of Science:
- Aquatic animal pathology
- Virology
- Infectious diseases
Background:
- Covert mortality nodavirus (CMNV) is known for cross-species transmission and widespread epidemics.
- The known host range of CMNV has not been extensively documented.
Purpose of the Study:
- To investigate the natural infection of Macrobrachium rosenbergii by CMNV.
- To determine the prevalence, target organs, and pathological effects of CMNV in M. rosenbergii.
Main Methods:
- TaqMan RT-qPCR for CMNV detection.
- Sequence analysis of the CMNV RNA-dependent RNA polymerase (RdRp) gene.
- In situ hybridization (ISH) and histology for tissue analysis.
- Transmission electron microscopy (TEM) for visualizing viral particles.
Main Results:
- CMNV was detected in 61.9% of M. rosenbergii samples from Jiangsu Province, indicating high prevalence.
- CMNV infection targeted the intestine, gill, hepatopancreas, and ovary, causing histopathological damage like vacuolation and karyopyknosis.
- CMNV presence in gonads suggests a potential risk of vertical transmission.
Conclusions:
- CMNV poses a significant threat to Macrobrachium rosenbergii aquaculture due to its high prevalence and pathogenicity.
- Further research is needed to understand the full impact of CMNV and identify strategies to mitigate its effects on M. rosenbergii populations.
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