Microgravity and low muon radiation affect viral pathogenesis and physiology in Caenorhabditis elegans

Spaceflight exposes organisms to unprecedented environmental stresses, including microgravity and reduced muon radiation. These conditions are known to impact immune functions, potentially influencing the severity of viral infections. This study investigates the effects of microgravity and below-background radiation ( i.e ., reduced muon radiation flux) on Orsay virus infections in Caenorhabditis elegans . We assessed C. elegans fitness-related and developmental traits under a fully factorial combination of standard or microgravity with standard or below-background radiation conditions. Our findings reveal that microgravity and below-background radiation affect fecundity, with significant negative impacts on reproductive success and developmental abnormalities in infected animals. Additionally, the interaction between these environmental factors and viral infection led to complex effects on viral accumulation, which were increased under below-background radiation but reduced in microgravity. These results provide new insights into the interplay between abiotic stresses and viral infections in space, emphasizing the need for further research on the long-term impacts of spaceflight on immune function and pathogen-host interactions.