Work

Genes expression in Penaeus monodon of Bangladesh; challenged with AHPND-causing Vibrio parahaemolyticus

Year: 2023

Type: article

Abstract: Vibrio parahaemolyticus, the causative agent of Acute hepatopancreatic necrosis disease (AHPND), was discovered in 2013 as unique isolates that produce toxins, kill penaeid shrimps in devasting nature in Bangladesh, and cause severe economic losses. This research aimed to understand the expressions of immune genes in different stages of host species, Penaeusmonodon against virulence and toxin genes upon challenged with V. parahaemolyticus. Healthy post-larvae (PL) samples were collected from southwestern Bangladesh. The tryptic soy agar with 1.5% sodium chloride (NaCl) was used to inoculate the cells of V. parahaemolyticus, and the tryptic soy broth (TSB) with 1.5% NaCl was used to transfer the colonies. The spectrophotometry measured bacteria density. PCR, qPCR, SDS-PAGE, and Western blot measured gene expression and survivability after immersion challenge. The 1×105CFU/mL of V. parahaemolyticus was used for 6 days challenge to six stages of post-larvae (PL) of P. monodon (PL20, PL25, PL30, PL35, PL40, and PL45), PL30 and PL35 showed 100% mortality by day 3 after exposure that indicated most vulnerable to V. parahaemolyticus. The expression of immune and toxic genes was confirmed by qPCR. The immune genes (toll-like receptor toll-like receptors (TLR), prophenoloxidaseProPO, lysozyme lyso, and penaeidin PEN) of PL20 and PL25 of P. monodon were expressed robustly up-trends. PL30 and PL35 showed the lowest gene expression at the end of the 3 days. At the end of the 6 days exposure, the immune genes TLR, ProPO, lyso, and PEN expressed highest in PL45 than other post-larvae stages of P. monodon. The toxic genes (pirA, ToxR, ToxA, ToxB, tlh, tdh, and trh) in PL30 and PL35 of P. monodon after exposure of V. parahaemolyticus were expressed highest at the end of the 3 days. The lowest toxic genes expressions were revealed in PL20 and PL45 at the end of 6 days. The SDS-PAGE analysis of proteins from the bacterium revealed identical protein profiles with toxic genes, and those toxins were further confirmed by Western blot. The 20kDa, 78kDa (ToxR), 20kDa, 25kDa (ToxA), 25kDa (ToxB), 20kDa, 27kDa, 75kDa (tdh), and 20kDa, 27kDa, 75kDa, and 78kDa (trh) proteins were strong responses in Western blot, indicating the crucial involvement of these immune-related genes in the defense and recovery of the first-line defense mechanisms during V. parahaemolyticus infection to shrimp. The all-toxic genes showed the unique homology and those derived from the common ancestor compared with V. parahaemolyticus (NCBI accession no. AP014859.1). All clades were derived with different traits with very low genetic distance, where the overall mean distance was 3.18 and showed a very uniform and homogenous pattern among the lineages. The V. parahaemolyticus infection process in different PL stages in P. Monodon showed novel insights into the immune responses. The responses may lead to the subsequent production of a DNA vaccine, enhancing shrimp health management to minimize the economic losses due to AHPND experiencing an outbreak of early mortality syndrome (EMS) toward sustainable production P. monodon (shrimp).

Source: Fish and Shellfish Immunology Reports

DOI: 10.1016/j.fsirep.2023.100092