Changes in the intestinal microbiota of Pacific white shrimp (Litopenaeus vannamei) with different severities of Enterocytozoon hepatopenaei infection

Correlation between variations in promoter region of LvITGβ gene and anti-infection trait of shrimp, Litopenaeus vannamei, against a microsporidium, Ecytonucleospora hepatopenaei

The growth and survival of shrimp Litopenaeus vannamei is significantly impacted by Ecytonucleospora hepatopenaei (EHP) infection, which has become one of the major threats to shrimp farming. Integrins (ITGs), functioning as cell adhesion receptors, play a critical role in the immune response of shrimps to EHP invasion. In this study, correlation between genetic variations in the promoter region of LvITGβ coding integrin β subunit and EHP-resistant trait of L. vannamei were deeply analyzed. Four experimental groups (ZJ01, ZJ02, ZJ03, and ZJ04) containing individuals with extreme EHP-resistant performances were selected to screen candidate genetic markers associated with EHP resistance, and subsequently the candidate genetic markers were further verified through using a VAL group. The relative expression of LvITGβ was significantly up-regulated in EHP-susceptible individuals reflected by higher EHP load. Chi-square (χ2) tests of individuals with extreme EHP-resistant performances revealed significant differences in allele distribution at loci, g.-722, g.-711, g.-294, and g.-268. Linkage disequilibrium analysis showed significant linkage between g.-294 and g.-268 (R2 = 0.33). A combined TT/AA genotype at the two loci considerably strongly associated with EHP resistance in four experimental groups, which was further verified in the VAL group. Therefore, this combined genotype was determined as a prominent SNP marker, and it has a huge application potential in genetic breeding of shrimp L. vannamei aiming at enhancing EHP resistance. These findings provide valuable insights for selecting shrimp individuals and breeding populations for enhanced resistance.

Microsporidian infection of mosquito larvae changes the host-associated microbiome towards the synthesis of antimicrobial factors

BACKGROUND

Microsporidians (Microsporidia) are a group of obligate intracellular parasites that commonly infect mosquitoes. Recently, it has been shown that infection by these parasites can alter the composition and functionality of the mosquito-associated microbiome. The host-associated microbiome of the mosquito can play a pivotal role in various physiological processes of this host, including its vector competence for pathogens. Thus, understanding how microsporidians shape the mosquito microbiome may be crucial for elucidating interactions between these parasites and their mosquito hosts, which are also vectors for other parasites and pathogens.

METHODS

The effects of microsporidian infection on the microbiome structure and functionality of Culex pipiens and Culex torrentium larvae under semi-natural conditions were examined. The host-associated microbiome of Cx. pipiens (n = 498) and Cx. torrentium (n = 465) larvae, including that of the 97 infected individuals of these samples, was analysed using 16S DNA profiling and functional prediction analysis.

RESULTS

Microbiome network analysis revealed that, in the microsporidian-positive larvae, host microbial communities consistently grouped within a common bacterial module that included Aerococcaceae, Lactobacillaceae, Microbacteriaceae, Myxococcaceae, and Polyangiaceae. Indicator species analysis revealed two strong positive correlations between microsporidian infection and the presence of Weissella cf. viridescens and Wolbachia pipientis. Functional predictions of microbiome content showed enrichment in biosynthetic pathways for ansamycin and vancomycin antibiotic groups in infected larvae. Furthermore, the MexJK-OprM multidrug-resistance module was exclusively present in the infected larvae, while carbapenem- and vancomycin-resistance modules were specific to the microsporidian-free larvae.

CONCLUSIONS

Our results demonstrate that microsporidian infection alters the microbial community composition in mosquito larvae. Moreover, they show that microsporidian infection can increase the antimicrobial capabilities of the host-associated microbiome. These results provide novel insights into host microbiome-parasite interactions and have potential implications for the vector competencies of mosquitoes.

Host-Parasite Interactions and Integrated Management Strategies for Ecytonucleospora Hepatopenaei Infection in Shrimp

BACKGROUND

Ecytonucleospora hepatopenaei (EHP) is a major parasitic pathogen in shrimp causing hepatopancreatic microsporidiosis, which leads to significant growth retardation and global economic losses. This pathogen employs various immune evasion strategies that complicate treatment and management.

PURPOSE

This review examines the complex host-parasite interactions, focusing on the immune evasion mechanisms used by EHP. The study explores how EHP manipulates host immune pathways, including NF-κB, JAK/STAT, Toll, and IMD, to suppress immune responses, inhibit antimicrobial peptide production, and avoid detection, thus ensuring its persistence in the host.

METHODS

The authors reviewed recent research from databases like PubMed, Scopus, and Web of Science, including studies up to 2024. The keywords Ecytonucleospora hepatopenaei, immune evasion, EHP treatment, and associated words with topics were used in this search.

RESULTS

EHP induces oxidative stress, which weakens the host immune system while simultaneously upregulating antioxidant responses to favor its survival. The parasite also alters the gut microbiota and disrupts key cellular processes, such as cell cycle regulation, further enhancing its ability to sustain infection.

CONCLUSION

This review highlights the need for integrated management strategies, including disease-resistant breeding, microbiota modulation, and advanced diagnostics, to combat EHP. By providing an overview of EHP's immune evasion tactics, this study aims to advance knowledge in the field and support efforts to improve shrimp health and aquaculture sustainability.

Therapeutic effects of fumaric acid on proteomic expression and gut microbiota composition in Pacific white shrimp (Penaeus vannamei) infected with Ecytonucleospora hepatopenaei (EHP)

Recently, microsporidiosis caused by a microsporidian [Ecytonucleospora (Enterocytozoon) hepatopenaei, EHP] has been found to seriously impact the global shrimp industry. The aim of this study was to evaluate the therapeutic effects of fumaric acid (FA) in EHP-infected Pacific white shrimp (Penaeus vannamei). In the first 2 groups, non-EHP-infected shrimp were fed FA-supplemented (10 g/kg diet) or normal feed (CM+ and CM-, respectively). The other 2 groups of EHP-infected shrimp were also fed FA-supplemented or normal feed (EM+ and EM-, respectively). All the experimental groups were fed for 7 days, and the hepatopancreas and intestine of the shrimp were sampled at 0, 1, 3 and 7 days after application (DAAs). The copy number of EHP in the hepatopancreas of the EM + shrimp was significantly lower than that in the hepatopancreas of the EM-shrimp at 3 and 7 DAAs (P < 0.01). Histopathological investigation revealed that the hepatopancreas of EM + shrimp began healing from microsporidiosis at 3 DAA and had almost completely recovered at 7 DAA. Proteomic analysis also revealed that the levels of immune-related proteins, such as β-1,3-glucan-binding proteins, the tumor suppressor TP53, and protein disulfide isomerase A3, were elevated in the hepatopancreas of the CM + shrimp compared with those in the control shrimp. Microbiome analyses from both LC‒MS/MS data and next-generation sequencing (NGS) of the shrimp intestine revealed that FA supplementation strongly affected the bacterial community in the shrimp gut. Based on the results from this study in the hepatopancreas of shrimp fed a diet of 10 g/kg FA for 7 days, FA strongly affected EHP proliferation; simultaneously, it increased the levels of several key molecules involved in oxidative stress, cellular stress and pattern recognition without harmful negative side effects; and effectively influenced the gut microbiota. This research is the first to show the effectiveness of FA in promoting shrimp health in the context of microsporidiosis in Pacific white shrimp and could be further applied in the global shrimp aquaculture industry.

Chitinase and proteinase K treatments enhance the DNA yield of microsporidium Ecytonucleospora hepatopenaei spores

Microsporidium Ecytonucleospora hepatopenaei (EHP) spores were purified from the hepatopancreas of Penaeus vannamei infected with EHP by percoll density gradient centrifugation and differential centrifugation. The EHP spores contain a thick chitin wall and might not rupture using the routine DNA extraction protocol. In this study, three enzymes were used, including chitinase, proteinase K, and DNase I. Chitinase or proteinase K digestions caused weakened fluorescence of chitin showing by a blurred edge of EHP spores stained with calcofluor white under a fluorescence microscope. Different combinations of these enzymes followed by DNA extraction with phenol-chloroform from EHP spores showed significant increases in the copy number of the EHP SSU gene per spore. The combination of the chitinase and proteinase K treatments resulted 4.46 ± 1.07 copies/spore detected, which is 31.6 ± 20.7 folds of no treatment groups, accounting to (55.7 ± 13.4)% of the total copies of the gene in the spore. The additional treatment with chitinase to the conventional extraction protocol with a proteinase K digestion step for feces and hepatopancreas samples of P. vannamei resulted in a significant difference in EHP copies in the DNA of (83.8 ± 64.1)% and (55.3 ± 88.0)% increases. The study proved that chitinase and proteinase K treatment enhance the DNA extraction from microsporidian spores resulting in high yield.

Interactions between microsporidia and other members of the microbiome

The microbiome is the collection of microbes that are associated with a host. Microsporidia are intracellular eukaryotic parasites that can infect most types of animals. In the last decade, there has been much progress to define the relationship between microsporidia and the microbiome. In this review, we cover an increasing number of reports suggesting that microsporidia are common components of the microbiome in both invertebrates and vertebrates. These microsporidia infections can range from mutualistic to pathogenic, causing several physiological phenotypes, including death. Infection with microsporidia often causes a disruption in the normal microbiome, with both increases and decreases of bacterial, fungal, viral, and protozoan species being observed. This impact on the microbiome can occur through upregulation and downregulation of innate immunity as well as morphological changes to tissues that impact interactions with these microbes. Other microbes, particularly bacteria, can inhibit microsporidia and have been exploited to control microsporidia infections. These bacteria can function through regulating immunity, secreting anti-microsporidia compounds, and, in engineered versions, expressing double-stranded RNA targeting microsporidia genes. We end this review by discussing potential future directions to further understand the complex interactions between microsporidia and the other members of the microbiome.

Interactions between the gut bacterial community of Exopalaemon carinicauda and infection by Enterocytozoon hepatopenaei

To explore the relationship between the intestinal flora of Exopalaemon Carinicauda and infection by Enterocytozoo Hepatopenaei (EHP), we analyzed the species and richness of gut microbiota in infected individuals in different EHP load groups [i.e., control (C), high load (H), and low load (L)] using gene sequencing after infection. The results showed that the abundance of intestinal flora in the high-load EHP group was significantly lower than that in the healthy group. Based on the UPGMA cluster tree and PCoA analysis, with comparisons to healthy shrimp, the gut microbiota of the EHP high load and low load groups were clustered into one branch, which indicated that EHP infection changed the composition of the gut microbiota of infected shrimps. The heat map analysis of species abundance clustering revealed that the dominant bacteria in the low EHP load group and the control group were beneficial genera such as Lactococcus, Ligilactobacillius, and Bifidobacterium, but the dominant bacteria in the high EHP load group were harmful genera such as Pseudomonas, Photobacterium, and Candidatus hepatincola. The functions of the intestinal flora predicted that most genes related to metabolism were more abundant in healthy shrimp, most genes related to metabolism and the organisms' system were more abundant in the low EHP load group, and most genes related to diseases and environmental information processing were more abundant in the high EHP load group. After separation and purification, the dominant bacteria (Bifidobacterium animalis in healthy shrimp and Lactococcus garvieae in the low EHP load group) and the non-dominant bacteria (Macrococus caseolyticus in the low EHP load group) were obtained. Each of these isolated strains were used together with EHP to infect E. carinicauda, and the results showed that Bifidobacterium animali and Lactococcus garvieae significantly reduced the EHP load in EHP-infected individuals. At the same time, the morphology and structure of the hepatopancreas and intestinal tissue of EHP-infected E. carinicauda were improved. No improvement was seen in tissue that was infected with Macrococus caseolyticus.

Integrated omics analysis reveals a correlation between gut microbiota and egg production in captive African penguins (Spheniscus demersus)

The egg production of captive African penguins differs considerably between individuals. An understanding of the physiological differences in African penguins with relatively greater and lesser egg production is meaningful for the captive breeding program of this endangered species. The objective of this study was to investigate differential microbial composition and metabolites in captive African penguins with different egg production. Fecal samples were collected from captive female African penguins during the breeding season. The results of 16 S rRNA gene sequencing showed that African penguins with different egg production had similar microbial diversities, whereas a significant difference was observed between their microbial community structure. African penguins with relatively greater egg production exhibited a higher relative abundance of Alphaproteobacteria, Rhizobiales, Bradyrhizobiaceae, Bradyrhizobium and Bosea. Meanwhile, penguins with relatively lesser egg production had an increased proportion of Klebsiella and Plesiomonas. We further identified a total of 1858 metabolites in female African penguins by liquid chromatography-mass spectrometry analysis. Among these metabolites, 13 kinds of metabolites were found to be significantly differential between African penguins with different egg production. In addition, the correlation analysis revealed that the egg production had significant correlations with most of the differential microbial bacteria and metabolites. Our findings might aid in understanding the potential mechanism underlying the phenomenon of abnormal egg production in captive African penguins, and provide novel insights into the relationship between gut microbiota and reproduction in penguins.

Investigating the transcriptomic variances in two phases Ecytonucleospora hepatopenaei (EHP) in Litopenaeus vannamei

This study explores the transcriptomic differences in two distinct phases of Ecytonucleospora hepatopenaei (EHP) in Litopenaeus vannamei, a crucial aspect in shrimp health management. We employed high-throughput sequencing to categorize samples into two phases, 'Phase A' and 'Phase B', defined by the differential expression of PTP2 and TPS1 genes. Our analysis identified 2057 genes, with 78 exhibiting significant variances, including 62 upregulated and 16 downregulated genes. Enrichment analyses via GO and KEGG pathways highlighted these genes' roles in cellular metabolism, signal transduction, and immune responses. Notably, genes like IQGAP2, Rhob, Pim1, and PCM1 emerged as potentially crucial in EHP's infection process and lifecycle. We hypothesize that these genes may influence trehalose metabolism and glucose provision, impacting the biological activities within EHP during different phases. Interestingly, a lower transcript count in 'Phase A' EHP suggests a reduction in biological activities, likely preparing for host cell invasion. This research provides a foundational understanding of EHP infection mechanisms, offering vital insights for future studies and therapeutic interventions.

Dynamic Interplay of Metabolic and Transcriptional Responses in Shrimp during Early and Late Infection Stages of Enterocytozoon hepatopenaei (EHP)

Enterocytozoon hepatopenaei (EHP) is a microsporidian parasite that infects Litopenaeus vannamei, causing severe hepatopancreatic microsporidiosis (HPM) and resulting in significant economic losses. This study utilizes a combined analysis of transcriptomics and metabolomics to unveil the dynamic molecular interactions between EHP and its host, the Pacific white shrimp, during the early and late stages of infection. The results indicate distinct immunological, detoxification, and antioxidant responses in the early and late infection phases. During early EHP infection in shrimp, immune activation coincides with suppression of genes like Ftz-F1 and SEPs, potentially aiding parasitic evasion. In contrast, late infection shows a refined immune response with phagocytosis-enhancing down-regulation of Ftz-F1 and a resurgence in SEP expression. This phase is characterized by an up-regulated detoxification and antioxidant response, likely a defense against the accumulated effects of EHP, facilitating a stable host-pathogen relationship. In the later stages of infection, most immune responses return to baseline levels, while some immune genes remain active. The glutathione antioxidant system is suppressed early on but becomes activated in the later stages. This phenomenon could facilitate the early invasion of EHP while assisting the host in mitigating oxidative damage caused by late-stage infection. Notably, there are distinctive events in polyamine metabolism. Sustained up-regulation of spermidine synthase and concurrent reduction in spermine levels suggest a potential role of polyamines in EHP development. Throughout the infection process, significant differences in genes such as ATP synthase and hexokinase highlight the continuous influence on energy metabolism pathways. Additionally, growth-related pathways involving amino acids such as tryptophan, histidine, and taurine are disrupted early on, potentially contributing to the growth inhibition observed during the initial stages of infection. In summary, these findings elucidate the dynamic interplay between the host, Litopenaeus vannamei, and the parasite, EHP, during infection. Specific phase differences in immune responses, energy metabolism, and antioxidant processes underscore the intricate relationship between the host and the parasite. The disruption of polyamine metabolism offers a novel perspective in understanding the proliferation mechanisms of EHP. These discoveries significantly advance our comprehension of the pathogenic mechanisms of EHP and its interactions with the host.

A comparative transcriptome analysis of how shrimp endure and adapt to long-term symbiosis with Enterocytozoon hepatopenaei infection

Enterocytozoon hepatopenaei (EHP) is a prevalent microsporidian pathogen responsible for hepatopancreatic microsporidiosis (HPM) in Litopenaeus vannamei. This infection not only leads to slowed growth in shrimp abut aslo inflicts substantial economic losses in the global aquaculture industry. However, the molecular mechanisms by which EHP influences the host during various infection stages remain unclear. This study employed comparative transcriptomics to examine the effects of EHP infection on Litopenaeus vannamei between early and late stage of infection groups. Utilizing transcriptomic approaches, we identified differentially expressed genes (DEGs) with notable biological significance through the COG, GO, KEGG, GSEA, and Mufzz time-series methodologies. The results reveal that EHP infection considerably influences host gene expression, with marked differences between early and late infection across distinct timeframes. Key processes such as detoxification, cell apoptosis, and lipid metabolism are pivotal during host-parasite interactions. Hexokinase and phosphatidic acid phosphatase emerge as key factors enabling invasion and sustained effects. Cytochrome P450 and glucose-6-phosphate dehydrogenase could facilitate infection progression. EHP significantly impacts growth, especially through ecdysteroids and 17β-estradiol dehydrogenase. By delineating stage-specific effects, we gain insights into interaction between EHP and Litopenaeus vannamei, showing how intracellular pathogens reprogram host defenses into mechanisms enabling long-term persistence. This study provides a deeper understanding of host-pathogen dynamics, emphasizing the interplay between detoxification, metabolism, immunity, apoptosis and growth regulation over the course of long-term symbiosis.

Intestinal Microbiota Differences in Litopenaeus vannamei Shrimp between Greenhouse and Aquaponic Rearing

The sustainability of shrimp aquaculture can be achieved through the development of greenhouse and aquaponic rearing modes, which are classified as heterotrophic and autotrophic bacterial aquaculture systems. However, there have been few investigations into the discrepancies between the intestinal and water microbiota of these two rearing methods. In this study, we collected shrimp samples from greenhouse-rearing (WG) and aquaponic-rearing (YG) ponds, and water samples (WE, YE), and investigated the intestinal and water microbiota between the two rearing modes. The results, through alpha and beta diversity analyses, reveal that there was basically no significant difference between shrimp intestine WG and YG (p > 0.05) or between rearing water WE and YE (p > 0.05). At the phylum and genus levels, the common bacteria between WE and WG differed significantly from those of YE and YG. The analysis of the top six phyla shows that Proteobacteria and Patescibacteria were significantly more abundant in the WG group than those in the YG group (p < 0.05). Conversely, Actinobacteriota, Firmicutes, and Verrucomicrobiota were significantly more abundant in the YG group than those in the WG group (p < 0.05). Venn analysis between WE and WG shows that Amaricoccus, Micrococcales, Flavobacteriaceae, and Paracoccus were the dominant bacteria genera, while Acinetobacter, Demequina, and Rheinheimera were the dominant bacteria genera between YE and YG. Pathways such as the biosynthesis of secondary metabolites, microbial metabolism in different environments, and carbon metabolism were significantly more upregulated in WG than those in YG (p < 0.05). In addition, pathways such as sulfate, chloroplast, phototrophy, and the nitrogen metabolism were significantly different between the WE and YE samples. These findings suggest that the greenhouse mode, a typical heterotrophic bacterial model, contains bacterial flora consisting of Amaricoccus, Micrococcales, Flavobacteriaceae, and other bacteria, which is indicative of the biological sludge process. Conversely, the aquaponic mode, an autotrophic bacterial model, was characterized by Acinetobacter, Demequina, Rheinheimera, and other bacteria, signifying the autotrophic biological process. This research provides an extensive understanding of heterotrophic and autotrophic bacterial aquaculture systems.