Nupur Pal, Sudeshna Sengupta, Rojina Khatun and Malavika Bhattacharya

Vertebrates exhibit a diverse array of highly sophisticated defense strategies that offers immediate as well as long-term protection against pathogens. Fundamental defence mechanisms such as phagocytosis, pattern recognition and related strategies of innate immune system are well conserved across all the metazoan species. While the adaptive immunity was discovered only after the rise of vertebrates. Among these vertebrates are Agnatha, represented by Lampreys and Hagfish－the only surviving vertebrates without jaw (jawless vertebrates). These jawless fish occupy a pivotal position in vertebrate immune system evolution. Despite lacking jaw, traditional lymphoid organs, and T or B lymphocytes found in higher vertebrates, agnathans possess a well-developed immune system that bridges innate and adaptive components of immune system. They use Variable Lymphocyte Receptors (VLRs) generated by gene-conversion like mechanism for selectively eliminating pathogens and have a unique complement system. This review paper explores specific components of immune system in Agnathans, highlighting their functional and structural role in the survival of these jawless vertebrates. By tracing the origins and complexity of immunity in vertebrates, the chapter presents a coherent overview of immune system evolution and sheds light on key features that actively withstood the evolutionary selection pressure.

Pages: 90-101  |  131 Views  86 Downloads