Transcriptomic Analysis Of The Gills,heart,and Hepatopancreas Of Pacific White Shrimp;Litopenaeus Vannamei After Vibrio Harveyi Infection

Shrimp aquaculture is a significant food-producing sector globally.Notwithstanding,it is being challenged with many problems,which include the outbreak of diseases,over-use of antibiotics,and changes in the environment.The level of the effects of these challenges on the immune system of the shrimp at the molecular level is yet to be fully apprehended.The Pacific white shrimp(Litopenaeus vannamei)is an essential aquaculture species globally.Nonetheless,Vibrio spp.infections have posed a tremendous economic loss in the sector.The immune responses of Litopenaeus vannamei to the Vibrio species infection is not fully studied.Hence it is of utmost importance to know the genes involved in immune response in L.vannamei.This study sought to provide useful information that will contribute to the understanding of L.vannamei immunity after Vibrio challenged.Below summarizes the main findings of the study: 1 Transcriptomic profile of L.Vannamei after Vibrio harveyi infection The current study revealed the transcriptomic data of L.vannamei gills,hepatopancreas,and heart which were injected with or without Vibrio harveyi.A total of 33,353 high-quality unigenes were obtained from RNAseq data.Comparative transcriptome analysis revealed 9,752 differentially expressed genes(DEGs)following the Vibrio harveyi infection,including 5,067 up-regulated and 4,687 down-regulated genes.Seven DEGs were randomly chosen for further confirmation by real-time RT-PCR,and the results revealed that their expression patterns are coherent with the obtained transcriptomic data.2 Gene expression pattern and tissue distribution As a result of the lack of a specific adaptive immunity,shrimp depend on an innate immune system to fight infections and diseases by identifying and destroying the invading disease-causing organisms through humoral and cellular immune responses.The current study focused on humoral immunity.Four genes believed to be involved in shrimp immune response including: the Single von Willebrand factor C-domain proteins(SVWC),C-Type lectins(CTLs),Chitin Binding protein(CBP),and Peneidin were selected for gene expression pattern and tissue distribution studies(Three up-regulating and one down-regulating).The results of the gene expression revealed that Single von Willebrand factor C-domain protein upregulated in the hepatopancreas,heart and intestine;the C-type lectins upregulated in the gills and intestines,the Chitin binding protein was upregulated in the hepatopancreas and heart and the penaeidin was downregulated in the hepatopancreas and heart following Vibrio harveyi infection.The results of tissue distribution showed that Single von Willebrand factor C-domain protein was expressed in the gills,heart,stomach,intestine,brain,and muscles with the highest expression in the gills.The C-Type lectin was expressed in the hemocytes,gills,stomach,intestine,nerves,brain,and muscle with the highest expression in the hemocytes and stomach.The Chitin Binding Protein was expressed in the hemocytes,eyestalk ganglion,gills,hepatopancreas,heart,stomach,intestine,nerve,brain,and muscle with the highest expression in the gills.The Peneidin was expressed in the hemocytes,gill,heart,stomach,intestine,and nerve with the highest expression in the hemocytes.3 RNAi and bacterial clearance assay To further extend our studies,RNAi experiments were performed.Double-stranded RNAs for the three up-regulating genes were prepared and injected into healthy shrimp to knock down expression of the genes and to also ascertain the functions of specific genes against V.harveyi by bacterial clearance analysis.The study found that the ability of L.vannamei to fight infections was significantly decreased when SVWC and C-Type Lectin were knocked-down,but the ability of L.vannamei to fight infections was increased when CBP was knocked down.The obtained results denoted that the three genes played critical roles in antibacterial immunity and have perculiar roles in fighting against invading pathogens.4 Conclusion In conclusion,the selected genes in this study were seen to participate in the L.vannamei immune response.The results will shed light on the immunity of L.vannamei and may facilitate the creation of a new technique to fight against the Vibrio infections in L.vannamei.