Differential Nervous Necrosis Virus (NNV) Replication in Five Putative Susceptible Cell Lines

Area of Science:

• Aquatic Animal Health
• Virology
• Fish Cell Culture

Background:

• Nervous necrosis virus (NNV) causes viral encephalopathy and retinopathy, a major threat to marine fish globally.
• Effective control strategies for NNV rely on successful in vitro propagation of viral strains.
• Assessing fish cell line susceptibility and permissiveness is crucial for optimizing NNV culture.

Purpose of the Study:

• To evaluate the susceptibility and permissiveness of five fish cell lines (E-11, GF-1, SAF-1, DLB-1, SaB-1) to three NNV strains.
• To identify the most suitable cell line for in vitro propagation of NNV.
• To inform the development of NNV diagnostic and control methods.

Main Methods:

• Inoculation of five fish cell lines (E-11, GF-1, SAF-1, DLB-1, SaB-1) with three NNV strains (RGNNV, SJNNV, reassortant).
• Measurement of average adsorption efficiency (AE) to determine susceptibility.
• Quantification of viral production rates (intracellular and extracellular) to assess permissiveness.

Main Results:

• E-11 and DLB-1 exhibited high NNV susceptibility (AE >90%), followed by SAF-1 (AE 88%) and GF-1 (AE ~50%). SaB-1 showed low susceptibility (AE <20%).
• E-11 and GF-1 demonstrated the highest permissiveness for RGNNV and reassortant NNV strains, with production rates around 10^3.
• E-11 was identified as the most appropriate cell line for in vitro culture of all tested NNV strains, showing high susceptibility and permissiveness.

Conclusions:

• The E-11 cell line is highly recommended for the in vitro propagation of various NNV strains, including RGNNV, SJNNV, and reassortants.
• Understanding cell line permissiveness is key to successful NNV research and the development of disease management strategies.
• This study provides a critical foundation for advancing NNV research and improving marine fish health.