The Pacific whiteleg shrimp (Penaeus vannamei) is a highly significant species in shrimp aquaculture. In the production of shrimp larvae, noticeable variations in the reproductive capacity among female individuals have been observed. Some females experience slow gonadal development, resulting in the inability to spawn, while others undergo multiple maturations and contribute to the majority of larval supply. Despite numerous studies that have been conducted on the regulatory mechanisms of ovarian development in shrimp, the factors contributing to the differences in reproductive capacity among females remain unclear. To elucidate the underlying mechanisms, this study examined the differences in the ovarian characteristics between high and low reproductive bulks at different maturity stages, focusing on the cellular and molecular levels. Transmission electron microscopy analysis revealed that the abundance of the endoplasmic reticulum, ribosomes, mitochondria, and mitochondrial cristae in oocytes of high reproductive bulk was significantly higher than that of the low reproductive bulk in the early stages of ovarian maturation (stages I and II). As the ovaries progressed to late-stage maturation (stages III and IV), differences in the internal structures of oocytes between females with different reproductive capacities gradually diminished. Transcriptome analysis identified differentially expressed genes (DEGs) related to the mitochondria between two groups, suggesting that energy production processes might play a crucial role in the observed variations in ovary development. The expression levels of the ETS homology factor (EHF) and PRDI-BF1 and RIZ homology domain containing 9 (PRDM9), which were significantly different between the two groups, were compared using qRT-PCR in individuals at different stages of ovarian maturation. The results showed a significantly higher expression of the EHF gene in the ovaries of high reproductive bulk at the II and IV maturity stages compared to the low reproductive bulk, while almost no expression was detected in the eyestalk tissue of the high reproductive bulk. The PRDM9 gene was exclusively expressed in ovarian tissue, with significantly higher expression in the ovaries of the high reproductive bulk at the four maturity stages compared to the low reproductive bulk. Fluorescence in situ hybridization further compared the expression patterns of EHF and PRDM9 in the ovaries of individuals with different fertility levels, with both genes showing stronger positive signals in the high reproductive bulk at the four ovarian stages. These findings not only contribute to our understanding of the regulatory mechanisms involved in shrimp ovarian development, but also provide valuable insights for the cultivation of new varieties aimed at improving shrimp fecundity.

The current study aimed to provide a precise assessment of the genetic parameters associated with growth and white spot syndrome virus (WSSV) resistance traits in Pacific white shrimp (Litopenaeus vannamei). This was achieved through a controlled WSSV challenge assay and the analysis of phenotypic values of five traits: body weight (BW), overall length (OL), body length (BL), tail length (TL), and survival hour post-infection (HPI). The analysis included test data from a total of 1017 individuals belonging to 20 families, of which 293 individuals underwent whole-genome resequencing, resulting in 18,137,179 high-quality SNP loci being obtained. Three methods, including pedigree-based best linear unbiased prediction (pBLUP), genomic best linear unbiased prediction (GBLUP), and single-step genomic BLUP (ssGBLUP) were utilized. Compared to the pBLUP model, the heritability of growth-related traits obtained from GBLUP and ssGBLUP was lower, whereas the heritability of WSSV resistance was higher. Both the GBLUP and ssGBLUP models significantly enhanced prediction accuracy. Specifically, the GBLUP model improved the prediction accuracy of BW, OL, BL, TL, and HPI by 4.77%, 21.93%, 19.73%, 19.34%, and 63.44%, respectively. Similarly, the ssGBLUP model improved prediction accuracy by 10.07%, 25.44%, 25.72%, 19.34%, and 122.58%, respectively. The WSSV resistance trait demonstrated the most substantial enhancement using both genomic prediction models, followed by body size traits (e.g., OL, BL, and TL), with BW showing the least improvement. Furthermore, the choice of models minimally impacted the assessment of genetic and phenotypic correlations. Genetic correlations among growth traits ranged from 0.767 to 0.999 across models, indicating high levels of positive correlations. Genetic correlations between growth and WSSV resistance traits ranged from (−0.198) to (−0.019), indicating low levels of negative correlations. This study assured significant advantages of the GBLUP and ssGBLUP models over the pBLUP model in the genetic parameter estimation of growth and WSSV resistance in L. vannamei, providing a foundation for further breeding programs.

C-type lectins are known for agglutination activity and play crucial roles in regulating the prophenoloxidase (proPO) activation system, enhancing phagocytosis and encapsulation, synthesizing antimicrobial peptides, and mediating antiviral immune responses. This work cloned a C-type lectin, ladderlectin (LvLL), from Litopenaeus vannamei. LvLL comprised a 531 bp open reading frame (ORF) that encoded 176 amino acids. The predicted LvLL protein included a signal peptide and a CLECT domain. LvLL was predicted to feature a transmembrane region, suggesting it may be a transmembrane protein. LvLL was predominantly expressed in the shrimp’s hepatopancreas. After WSSV infection, LvLL expression in the hepatopancreas increased significantly by 11.35-fold after 228 h, indicating a general upregulation. Knockdown of LvLL resulted in a significant decrease in WSSV viral load and a notable increase in shrimp survival rates. Additionally, knockdown of LvLL led to a significant downregulation of apoptosis-related genes Bcl-2 and caspase 8 and a significant upregulation of p53 and proPO in WSSV-infected shrimp. This study showed that LvLL played a vital role in the interaction between L. vannamei and WSSV.

Penaeus vannamei aquaculture production accounts for the majority of total shrimp aquaculture output, but it has suffered a severe decline in production and economic losses due to WSSV disease. Therefore, elucidating the relationship between the host immune system and pathogens is crucial for shrimp disease prevention and control. Integrins, as receptor-related molecules, have been shown to participate in various physiological functions, including cell migration, organismal development, and the pathogenesis of multiple diseases. However, the regulatory mechanisms of integrin genes in the shrimp immune system remain unclear. This study reports that integrins may regulate the Toll, IMD, and STAT signaling pathways in P. vannamei by influencing Spätzle, TLR, and Domeless, thereby affecting the shrimp’s innate immune system against diseases. Additionally, integrins can inhibit viral entry and replication. Through RNA interference (RNAi) experiments, it was found that knocking down Pv-Integrin β increases the viral load of white spot syndrome virus (WSSV), making shrimp more susceptible to WSSV and giving rise to increasing mortality. Further research indicates that Pv-Integrin β acts as an upstream recognition receptor in the disease resistance immune pathway, influencing other signaling pathway receptors to regulate the innate immune system. Importantly, knocking down Pv-Integrin β upregulates the expression of antimicrobial peptides such as ALF1 and ALF2, but reduces the expression of Crustin1, Crustin2 and prophenoloxidase. In conclusion, this study reveals that Pv-Integrin β regulates the disease resistance immune signaling pathways by affecting the related receptors.

This study evaluated the genetic parameters for growth and Vibrio parahaemolyticus (Vp_AHPND) resistance in both the introduced MK strain and the self-constructed GK strain of Penaeus vannamei, investigating the impact of genotyped female parents on trait estimates under a single-parent nested mating design. A total of 32 families from the MK strain and 44 families from the GK strain were analyzed. Fifty-four female parents from both strains were genotyped using the “Yellow Sea Chip No. 1” containing 10.0 K SNPs. In the MK strain, heritability estimates ranged from 0.439 to 0.458 for body weight (Bw) and from 0.308 to 0.489 for survival time (ST) and survival rates at 36 h (36 SR), 50% mortality (SS₅₀), and 60 h (60 SR). In the GK strain, heritability for Bw ranged from 0.724 to 0.726, while ST, 36 SR, SS₅₀, and 60 SR had heritability estimates between 0.370 and 0.593. Genetic correlations between Bw and ST were 0.601 to 0.622 in the MK strain and 0.742 to 0.744 in the GK strain. For Bw and survival rates, correlations ranged from 0.120 to 0.547 in the MK strain and from 0.426 to 0.906 in the GK strain. The genetic correlation between ST and survival rates was not significantly different from 1 (p > 0.05) in both strains. High Pearson correlations (0.853 to 0.997, p < 0.01) were observed among survival rates at different points. Predictive accuracies for Bw, ST, and survival rates using single-step genomic best linear unbiased prediction (ssGBLUP) were comparable to pedigree-based best linear unbiased prediction (pBLUP) in the MK strain, while in the GK strain, ssGBLUP improved predictive accuracies for Bw, ST, and SS₅₀ by 0.20%, 0.32%, and 0.38%, respectively. The results indicate that both growth and Vp_AHPND resistance have significant breeding potential. Although the genetic correlation between weight and resistance varies across different populations, there is a positive genetic correlation between these traits, supporting the feasibility of multi-trait selection. To enhance genetic accuracy, breeding programs should include more genotyped progeny. These findings also suggest that infection frequency and observation time influence resistance performance and breeding selection, emphasizing the need for a tailored resistance evaluation program to improve breeding efficiency and reduce costs.

Reproductive inefficiency remains a major constraint in Penaeus vannamei hatcheries due to high rates of non-spawning females. This study presents the first two-generational quantitative genetic analysis of female reproductive performance under standardized SPF (Specific Pathogen-Free) conditions. A total of 986 females across two generations (2021–2022) from 198 full-sib and 68 half-sib families were evaluated. Traits analyzed included spawning frequency (SF), mean spawning interval (MSI), number of eggs laid for the first time (NE1), average spawning (AS), total spawning (TS), and spawning success (SS). Heritability estimates for SF, SS, and TS were moderate (0.30 ± 0.06, 0.23 ± 0.06 and 0.28 ± 0.07, respectively), while MSI, NE1, and AS showed low heritability (0.10–0.16). When analyzed separately by year, heritability estimates declined substantially for most traits in the second generation. Strong positive genetic correlations were observed between SF, MSI, NE1, AS, and TS, with pairwise estimates ranging from 0.82 to 0.99, indicating that these traits are under shared genetic control. Despite not being direct selection objects, all reproductive traits exhibited relative genetic progress (246–488% per generation), which is attributable to the high selection intensity applied to the parental generation. Our findings provide a robust foundation for integrating reproductive performance into breeding programs for P. vannamei, particularly under biosecurity and commercial feed-dominated conditions.