Ecytonucleospora hepatopenaei causes lipid droplet depletion and imbalanced lipid metabolism in Penaeus vannamei

EHP Infection: Starving the Shrimp from the Inside

Topic Overview

        Whiteleg shrimp (Penaeus vannamei) is a cornerstone of global aquaculture, but a tiny parasite called Ecytonucleospora hepatopenaei (EHP) poses a major threat. EHP doesn’t usually kill the shrimp, but it causes severe growth retardation, leading to significant economic losses for farmers worldwide. Because EHP is an obligate parasite, it must steal all its energy from the host shrimp to survive.

Paper Findings
        Our study investigated how EHP damages shrimp by focusing on lipid metabolism, as fat is the most energy-dense resource for any organism. We found that EHP infection progressively impairs two key systems:

1. Impaired Digestion: EHP causes a progressive drop in the activity and production of vital digestive enzymes (like trypsin, amylase, and lipase). This means the shrimp cannot effectively digest and absorb nutrients from the food they eat.
2. Lipid Reservoir Depletion: Crucially, we found that EHP causes a chronic, severe depletion of the shrimp’s internal fat reserves (called lipid droplets) from the very beginning of the infection. This depletion happens because the parasite triggers the shrimp’s system to break down fat faster than it can synthesize new fat. The effect is essentially draining the shrimp’s primary energy battery.

Key Takeaways
        The growth retardation seen in EHP-infected shrimp is a direct result of this double blow: poor nutrient intake from impaired digestion, coupled with the forced starvation of their internal fat stores. This imbalance drains the host’s energy and impairs its health over the long term.

        These findings suggest that a practical management strategy could involve supplementing the shrimp’s diet with high-quality lipids, which might help the shrimp counteract the metabolic disruption caused by EHP and ultimately lessen the growth stunting.