兔抗条纹斑竹鲨IgNAR多克隆抗体的制备和应用

目的 制备条纹斑竹鲨IgNAR的多克隆抗体,为条纹斑竹鲨单域抗体的开发提供工具。方法 合成条纹斑竹鲨IgNAR恒定区的一段多肽作为抗原,免疫新西兰大白兔,制备多克隆抗体血清,采用间接ELISA法测定抗体的效价,并通过Western blotting检测多克隆抗体的特异性。此外,利用制备的多克隆抗体对条纹斑竹鲨外周血淋巴细胞进行免疫荧光和流式分析。结果 制备的抗血清效价高达1000万,该多克隆抗体不仅能识别条纹斑竹鲨的IgNAR,还能识别护士鲨的IgNAR,但对条纹斑竹鲨的灵敏度更高。通过免疫荧光和流式细胞术确定了该多克隆抗体还可以识别条纹斑竹鲨外周血淋巴细胞跨膜型IgNAR。结论 成功制备了条纹斑竹鲨IgNAR的多克隆抗体,该抗体可用于Western blotting、免疫荧光和流式细胞术等实验,为条纹斑竹鲨单域抗体的开发提供了有力工具。     

Description of an elasmobranch TCR coreceptor: CD8α from Rhinobatos productus

Cell-mediated immunity plays an essential role for the control and eradication of intracellular pathogens. To learn more about the evolutionary origins of the first signal (Signal 1) for T-cell activation, we cloned CD8α from an elasmobranch, Rhinobatos productus. Similar to full-length CD8α cDNAs from other vertebrates, Rhpr-CD8α (1800 bp) encodes a 219 amino acid open reading frame composed of a signal peptide, an extracellular IgSF V domain and a stalk/hinge region followed by a well-conserved transmembrane domain and cytoplasmic tail. Overall, the mature Rhpr-CD8α protein (201 aa) displays ∼30% amino acid identity with mammalian CD8α including absolute conservation of cysteine residues involved in the IgSf V domain fold and dimerization of CD8αα and CD8αβ. One prominent feature is the absence of the LCK association motif (CXC) that is needed for achieving signal 1 in tetrapods. Both elasmobranch and teleost CD8α protein sequences possess a similar but distinctly different motif (CXH) in the cytoplasmic tail. The overall genomic structure of CD8α has been conserved during the course of vertebrate evolution both for the number of exons and phase of splicing. Finally, quantitative RTPCR demonstrated that elasmobranch CD8α is expressed in lymphoid-rich tissues similar to CD8 in other vertebrates. The results from this study indicate the existence of CD8 prior to the emergence of the gnathostomes (>450 MYA) while providing evidence that the canonical LCK association motif in mammals is likely a derived characteristic of tetrapod CD8α, suggesting potential differences for T-cell education and activation in the various gnathostomes.     

Single-domain antibodies for biomedical applications

Abstract

Single-domain antibodies are the smallest antigen-binding units of antibodies, consisting either only of one variable domain or one engineered constant domain that solely facilitates target binding. This class of antibody derivatives comprises naturally occurring variable domains derived from camelids and sharks as well as engineered human variable or constant antibody domains of the heavy or light chain. Because of their high affinity and specificity as well as stability, small size and benefit of multiple re-formatting opportunities, those molecules emerged as promising candidates for biomedical applications and some of these entities have already proven to be successful in clinical development.     

天然小分子抗体研究进展

与传统意义上的由两条重链和两条轻链组成的单体抗体不同,天然小分子抗体是指在自然界中存在的一些奇特的小分子抗体,它们分子量比较小,有的仅由重链组成,有的仅由轻链组成。在骆驼体内发现的仅由重链组成的抗体可以发挥正常的生物学功能,克隆其可变区即获得具有抗原结合能力的纳米抗体(Nanobody)。鲨鱼体内也存在一种由重链同源二聚体组成的非典型抗体IgNAR。另外,在人体内也存在游离的轻链抗体(FLC),在疾病的发生诊断中具有重要意义。本文综述了Nanobody、IgNAR及FLC的结构特点与作用机制。