Software M code for exploring virus dynamics in multi-species systems

In recent decades, the global expansion of Pacific oyster (Crassostrea gigas) aquaculture, driven by its adaptability and rapid growth, has coincided with the emergence of novel microvariants (vars) of the virulent Ostreid herpesvirus 1 (OsHV-1), causing significant industry losses. As a potential alternative, the American oyster (Crassostrea virginica) demonstrates lower susceptibility to 4OsHV-1. This study developed a transmission model for OsHV-1 in mixed oyster aquaculture systems, focusing on the impact of C. virginica introductions on transmission dynamics within established C. gigas systems. The model considers oyster growth, mortality, filtration, viral particle release, and environmental decay. Simulations, including monoculture and co-culture scenarios (10/90, 40/60, 50/50 proportions), were validated against experimental data. Results indicated that introducing C. virginica did not impede OsHV-1 progression; even in the 90/10 system, C. gigas mortality reached its maximum, albeit delayed by approximately 10 days. Co-culture scenarios did not provide a significant advantage for C. gigas, likely due to viral particle saturation in the water column. The model’s performance across diverse scenarios positions it as a valuable tool for understanding waterborne pathogen dynamics in mixed host-species systems, supporting investigations into aquaculture species introductions and their influence on disease dynamics.