Vibriosis is an infectious disease caused by the bacteria Vibrio that causes huge financial losses to shrimp farmers. To solve this problem, scientists have found a way to breed broodstock that are stable resistant to genetic diseases.
Genetic research in shrimp is still in its early stages.
A new study has revealed the mechanisms behind drug resistance in this disease. A team of scientists from the institute analyzed the mechanism of resistance to vibriosis in the gut microbiota of shrimp, based on disease-resistant and susceptible Penaeus vannamei strains obtained through selective breeding.
1. Breeding methods for disease resistance
Selection and breeding of disease-resistant varieties is an effective and sustainable strategy for vibriosis control. Several strains of disease-resistant broodstock have been established. Based on these strains, previous studies have focused on identifying genetic variants and differentially expressed genes (DEGs) between disease-resistant and susceptible shrimp families in search of targets that lead to disease resistance. In previous studies, polymorphisms in immune genes such as LvALF and TRAF6 were thought to be associated with disease resistance in shrimp. However, despite the abundance of genetic data available, the main mechanisms of disease resistance remain unclear.
2. Epigenetics in aquaculture
In addition to the genetic basis, the process of genetic remodeling also plays a functional role in the formation of aquaculture traits. Epigenetic research in shrimp is still in its infancy, and environmental factors, including pathogens and artificial selection, can influence epigenetic changes and produce new genes that can be passed on to future generations.
DNA methylation is one of the most studied genetic mechanisms, mainly related to the negative regulation of gene expression. However, to date, the functional role of methylation and other genetic regulators in the formation of shrimp aquaculture traits has not been reported.
3. Gut microbiota and disease resistance
A dense and diverse microbiota lives in the gut and co-evolves with the host. The gut microbiota is a major regulator of physiology, immunity, and physical health. The main function of the gut microbiota is to help the host resist the invasion of pathogens and the overgrowth of local pathogenic bacteria, which is known as the invasion defense mechanism. Researchers report that in some families of disease-resistant animals, probiotics are added to the gut that can effectively inhibit the growth of pathogens.
Through four generations of artificial selection, the researchers created resistant and infected-prone strains of Penaeus vannamei.
Therefore, the formation of disease-resistant bacterial communities will have a profound impact on the improvement of host disease resistance. However, the composition of the gut microbiota is influenced by many factors, and it is unclear whether the host is able to establish a disease-resistant bacterial community during artificial selection, and what may contribute to its formation.
4. Research on the resistance of V. vannamei shrimp
In this study, the researchers analyzed the mechanisms of resistance of host and commensal microorganisms to Vibrio based on artificially selected Vibrio-resistant and infestation-prone broodstock strains. The role of genetic regulation and gut microbiota in Vibrio resistance has been determined by sequencing colonies, transcriptomes, and microbiota and treatment with methyltransferase inhibitors. According to the study authors, this study is the first to comprehensively investigate DNA methylation patterns across the genome, as well as changes in the microbiota between drug-resistant and susceptible families.
5. Bacteriological protective cover
Researchers have created resistant and susceptible strains of Penaeus vannamei through four generations of artificial selection. Surprisingly, the authors found that the shrimps had developed resistance to the invasion of Vibrio. The key to this antimicrobial ability lies in the composition of their gut microbiota. Antimicrobial shrimp exhibit specific reproduction of a single probiotic species, Cheyvanella. This beneficial bacteria play an important role in reducing the vibrio load.
6. Genetic memory of antimicrobial resistance
What is even more surprising is that this antimicrobial ability is hereditary and influenced by epigenetic changes in shrimp. These changes, which affect gene expression without altering the DNA sequence, appear to be fundamental to the development of antimicrobial abilities. Scientists have identified a set of genes that are specifically activated in antimicrobial shrimp due to a decrease in DNA methylation. These genes are involved in the production of lactate and the balance of iron, creating a favorable environment for the growth of Cheyverne. In turn, the increase in lactic acid favors shrimp to survive infectious diseases caused by Vibrio.
The composition of the gut microbiota is influenced by a variety of factors.
7. What does the shrimp industry mean?
The results of this study have important implications for the aquaculture industry. Understanding the mechanisms of resistance to vibriosis will allow us to develop more effective strategies for the prevention and control of the disease, and in addition, the selection of shrimp strains with stable genetic resistance can significantly improve the sustainability and profitability of the industry.
Overall, this study is based on the interaction between gut microbiota, shrimp genetics, and genetic factors, revealing complex defense mechanisms for shrimp vibriosis. These findings open new doors for the development of healthier and more sustainable farming strategies.