International Journal of Molecular Veterinary Research, 2025, Vol.15, No.1, 1-12 http://animalscipublisher.com/index.php/ijmvr 2 2 Structure and Function of Immune System Genes in Mammals 2.1 Key immune system components and pathways Mammalian immune responses are made up of two major components: innate and adaptive immunity. Innate immunity is the first line of defense against pathogens and employs pattern recognition receptors (PRRs) such as toll-like receptors (TLRs) to recognize pathogen-associated molecular patterns (PAMPs) and endogenous damage-associated molecular patterns (DAMPs) (Nie et al., 2018). TLRs are some of the most conserved and oldest of the PRRs and play a crucial role in initiating immune responses across a wide variety of species, from invertebrates to mammals (Nie et al., 2018). The adaptive immune system is distinguished by its ability to generate a clonally diverse population of lymphocytes, each having unique antigen receptors. This mechanism was evolved in vertebrate ancestors and provides an advantage of survival by enabling the identification and rejection of pathogen intruders through recombinatorial shuffling of immunoglobulin or T cell receptor gene segments (Cooper and Alder, 2006). 2.2 Classification of immune genes: innate vs. adaptive Immune genes may be broadly classified into those that operate in the innate and the adaptive immune systems. The innate immune genes are those that code for PRRs like TLRs to directly cause pathogen recognition and downstream signaling cascades (Nie et al., 2018). The genes are conserved among species, indicative of their critical role in immune defense. Adaptive immune genes do create diverse antigen receptors, though, by processes such as V(D)J recombination in jawed vertebrates or leucine-rich-repeat genetic module assembly in jawless vertebrates like lampreys and hagfish (Cooper and Alder, 2006). The dualism highlights the innovation that has developed in order to allow vertebrates to construct sophisticated pathogen recognition and response mechanisms. 2.3 Comparison of immune gene function across mammals The function of immune genes is varied across different mammalian species and reflects both conserved processes as well as species-specific evolution. TLRs, for instance, have similar domain structure and signaling pathways in organisms as varied as mammals (Nie et al., 2018). However, functional diversification and evolution of new signaling pathways and adaptors has occurred, leading to variations in immune response across different species (Nie et al., 2018). In the adaptive immune system, jawed vertebrates have conserved mechanisms for creating diversity of antigen receptors, but they could be different with regard to distinct genetic changes and pathways. For example, even though all jawed vertebrates use recombinatorial rearrangement of T cell receptor or immunoglobulin gene segments, jawless vertebrates like lampreys and hagfish possess a different system using leucine-rich-repeat genetic modules (Cooper and Alder, 2006). These differences unveil the evolutionary diversity and imagination in immune gene function across mammals. 3 Genomic Advances in Studying Canid Immunity 3.1 Sequencing and annotation of canid genomes Evolution of next-generation sequencing (NGS) technologies has revolutionized canid genome studies with the ability to perform high-throughput sequencing and detailed annotation of genetic information. The technologies enabled sequencing a number of species of canids and provide immense amounts of genomic data that may be used to examine the genetic basis of immune response. For instance, NGS has been central in annotating and identifying immune genes in different species so that scientists can compare and gain insights on the evolutionary dynamics of the immune genes (Clark and Greenwood, 2016). The application of NGS in model organisms, such as canids, has also hinted at the challenges in gene annotation, particularly for rapidly evolving immune genes that may not be well captured in available databases. 3.2 Identification and cataloging of immune genes Canid immune gene characterization and classification have also been significantly facilitated by comparative transcriptomics and genomics. Comparative approaches have enabled immune gene repertoires in various species to be revealed with hints of conserved and divergent immune aspects. For clarification, it has already been shown in studies that genes that are involved in the recognition of pathogens and direct pathogen inhibition are under
RkJQdWJsaXNoZXIy MjQ4ODYzNA==