Shrimp aquaculture is the most promising food production sector providing protein-rich supplements for human consumption. It has changed from extensive, traditional, small-scale practices to an intensive, scientific, large scale global industry in the last three decades. The intensive shrimp aquaculture is associated with serious disease outbreaks that are responsible for the production loss either due to the reduction of growth rate or mortality caused by various pathogenic microorganisms.
Pathogen control in aqua animals is highly challenging as they are transmitted rapidly through water unlike pathogens of terrestrial animals. High stocking density is one of the major factors aiding the easy transmission of pathogens.
Out of the various infectious diseases that have caused devastating collapses of the shrimp industry, Hepatopancreac Microsporidiosis (HPM) caused by Enterocytozoon hepatopanaei (EHP) is the most difficult to control as there is no effective treatment available with the shrimp farmers and very difficult to eradicate once the spores get settled in the ponds.
The main clinical sign of EHP is growth retardation, which leads to increased variability in size. In a more advanced stage, EHPinfected shrimp typically display so shells, lethargy, reduced feed intake, and empty midgut. EHP is currently diagnosed through histological examination, in situ hybridization, and PCR. EHP is an intracellular microsporidian that replicates within the cytoplasm of the affected tubule epithelial cells in the hepatopancreas.
Histology of infected issues reveals several developmental stages, including basophilic inclusion bodies within the cytoplasm of the hepatopancreas EHP primarily infects the tubule epithelial cells of hepatopancreas via a highly specialized polar tube which it extends from its cell wall into the epithelial cell forming a pore in the host cell. Through this pore via the specialized polar tube, it injects its sporoplasm into the host cells. The sporoplasm now differentiates into meronts inside the host cytoplasm then sporonts and lastly mature spores that are finally released ready to infect other healthy cells.
Host cell Rupture of the host cell and release of spores Sporogon differentiation/maturation Parasitophorous vacuole full of spores Merogony proliferation Exospore Nucleus Endospore Proliferative forms Spore Anchoring disc Polar tube coil Posterior vacuole Mode of Transmission Shed in ponds Ingestion Co-habitation DNA Host cell
Primary sites of infection: Hepatopancreas Spore Germination Sporoplasm polar filament extrusion REHPAIRO is a safe biotechnological innovation for controlling the EHP infection and increasing the efficiency of high-quality protein in aquafeeds.
It not only enhances productivity but also helps to improve the quality which positively influences processing characteristics. It also addresses the environmental concerns of eutrophication and pollution associated with excess nutrient waste.
REHPAIRO also optimizes the utilization of protein depending on the optimal dietary amino acid profile of a species for protein synthesis. If the amino acid profile is poorly correlated to the requirement of the shrimp, then it leads to lower retention of synthesized protein. REHPAIRO improves the retention of the synthesized protein from the feed leading to higher growth rates and low protein turnover.
Mechanism for EHP Reduction
- The Phyto-active components of REHPAIRO prevent adhesion of EHP spore wall and the tubule epithelial cells of shrimp hepatopancreas
- Checks virulence of EHP spores by killing them outside the cell or in the gut lumen
- Interrupts the polar tube extension to the host cell by digesting the polar tube components, thereby blocking the infection procedure
- Enhances the recovery of shrimp digestive system and improves the health condition
EHP – Host Cell Mechanism
- Assists in activating the function of hepatopancreas
- Aids in control of EHP/ HPM / WFS in shrimps
- Helps in achieving faster growth and body weight gain