Polymeric immunoglobulin receptor (pIgR) is a protein that transports Immunoglobulins (Igs) from epithelial cells into the external secretion system of the animal. In the present study, we characterized the partial pIgR gene from Labeo rohita and analyzed its expression in response to the pDNA (pGPD-IFN) vaccine, and studied its correlation with the expression of IgM, in the mucosal-associated lymphoid tissues (MALT). The significant (p < 0.05) up-regulation of pIgR mRNA was observed in the mucosal tissues of vaccinated fish by qRT-PCR. The highest expression of the gene was detected in gill tissue at 15 days post-vaccination (dpv) followed by skin and gut at 30 dpv. The expression of IgM also showed a similar pattern and indicated a direct correlation of pIgR expression in all the tested tissues. The protective immune response of the DNA vaccine was measured as the relative percentage of survival (RPS) by challenging vaccinated fish with live Edwardsiella tarda (1 × 10⁵ CFU/Fish). The result showed a significantly high relative percentage survival (RPS) in the vaccinated group (47.05%) compared to the control group. Many factors contributing to the immune response of the vaccine. One of the most critical aspects is the rise in IgM level in local tissues. In other higher vertebrates, pIgR is reported to act as the transporter of IgM. The positive correlation in the expression of pIgR and IgM observed in the present study demonstrated the possible role of pIgR as the transporter of IgM in L. rohita. The study suggests the possibility of the secretory nature of IgM in fish.

聚合免疫球蛋白受体（pIgR）是一种将免疫球蛋白（Igs）从上皮细胞转运到动物外部分泌系统的蛋白。在本研究中，我们表征了Labeo rohita的部分pIgR基因，并分析了其对pDNA（pGPD-IFN）疫苗的反应，并研究了其与粘膜相关淋巴组织（MALT）中IgM表达的相关性。 。该显著（p ≤0.05）通过qRT-PCR在接种鱼的粘膜组织中观察到pIgR mRNA的上调。接种后15天（dpv）在g组织中检测到该基因的最高表达，然后在30 dpv时在皮肤和肠道中检测到该基因的最高表达。IgM的表达也显示出相似的模式，并表明在所有测试组织中pIgR的表达具有直接相关性。DNA疫苗的保护性免疫反应通过用活的爱德华氏菌（Edwardsiella tarda）（1×10 ⁵CFU /鱼）。结果显示，与对照组相比，接种组的相对存活率（RPS）显着较高（47.05％）。造成疫苗免疫反应的因素很多。最关键的方面之一是局部组织中IgM水平的升高。在其他高等脊椎动物中，据报道pIgR充当IgM的转运蛋白。本研究中观察到的pIgR和IgM表达呈正相关，证明了pIgR作为L. rohita中IgM转运蛋白的可能作用。该研究表明鱼中IgM具有分泌性质的可能性。