Université Paris-Saclay, INRAE, UVSQ, Virologie et Immunologie Moléculaires, Jouy-en-Josas, France.
Immunology Laboratory, Biomedical Research Center (CINBIO), University of Vigo, Campus Lagoas Marcosende, Vigo, Pontevedra, Spain.
J Immunol. 2022 Jun 1;208(11):2573-2582. doi: 10.4049/jimmunol.2200088. Epub 2022 May 16.
Upon infection, B lymphocytes develop clonal responses. In teleost fish, which lack lymph nodes, the kinetics and location of B cell responses remain poorly characterized. Fish pronephros is the site of B cell differentiation and the main niche for persistence of plasma cells. In this study, we undertook the analysis of the rainbow trout IgHμ repertoire in this critical tissue for humoral adaptive immunity after primary immunization and boost with a rhabdovirus, the viral hemorrhagic septicemia virus (VHSV). We used a barcoded 5' RACE-cDNA sequencing approach to characterize modifications of the IgHμ repertoire, including VH usage in expressed V(D)J rearrangements, clonal diversity, and clonotype sharing between individual fish and treatments. In the pronephros, our approach quantified the clonotype frequency across the whole IgH repertoire (i.e., with all VH), measuring the frequency of Ag-responding clonotypes. Viral infection led to extensive modifications of the pronephros B cell repertoire, implicating several VH subgroups after primary infection. In contrast, only modest changes in repertoire persisted 5 mo later, including VHSV-specific public expansions. The IgM public response implicating IgHV1-18 and JH5, previously described in spleen, was confirmed in pronephros in all infected fish, strongly correlated to the response. However, the distribution of top clonotypes showed that pronephros and spleen B cells constitute distinct compartments with different IgH repertoires. Unexpectedly, after boost, the frequency of anti-VHSV clonotypes decreased both in pronephros and spleen, raising questions about B cell circulation. A better monitoring of B cell response kinetics in lymphoid tissues will be an essential step to understand B memory and plasmocyte formation mechanisms in fish.
在感染后，B 淋巴细胞会产生克隆反应。在没有淋巴结的硬骨鱼类中，B 细胞反应的动力学和位置仍未得到很好的描述。鱼类的前肾是 B 细胞分化的部位，也是浆细胞持续存在的主要场所。在这项研究中，我们在前肾中分析了虹鳟鱼 IgHμ 库，这是体液适应性免疫的关键组织，在原发性免疫和用弹状病毒——病毒性出血性败血症病毒（VHSV）进行加强免疫后。我们使用了带有条形码的 5' RACE-cDNA 测序方法来描述 IgHμ 库的修饰，包括表达的 V(D)J 重排中 VH 的使用、克隆多样性以及个体鱼和处理之间的克隆型共享。在前肾中，我们的方法通过定量整个 IgH 库（即使用所有 VH）中的克隆型频率，测量了抗原反应性克隆型的频率，来对 B 细胞库进行定量。病毒感染导致前肾 B 细胞库发生广泛修饰，涉及到原发性感染后的几个 VH 亚群。相比之下，5 个月后，只有适度的库变化持续存在，包括 VHSV 特异性的公共扩展。在所有感染的鱼中，以前在脾脏中描述的 IgM 公共反应（涉及 IgHV1-18 和 JH5）在前肾中得到了证实，与反应强烈相关。然而，顶级克隆型的分布表明，前肾和脾脏 B 细胞构成了具有不同 IgH 库的不同隔室。出乎意料的是，在加强免疫后，抗 VHSV 克隆型在前肾和脾脏中的频率都降低了，这引发了关于 B 细胞循环的问题。更好地监测淋巴组织中 B 细胞反应的动力学将是理解鱼类 B 细胞记忆和浆细胞形成机制的重要步骤。
