Screening and Identification of the First Non-CRISPR/Cas9-Treated Chinese Miniature Pig With Defective Porcine Endogenous Retrovirus pol Genes

International Xenotransplantation Association (IXA) Position Paper on Infectious Disease Considerations in Xenotransplantation

Clinical xenotransplantation has the potential to address shortages of human organs for patients with end-stage organ failure. Advances in genetic engineering, immunosuppressive regimens, and infectious disease diagnostics have improved prospects for clinical xenotransplantation. Management of the infectious risks posed by clinical xenotransplantation requires biosecure breeding and validated methods for microbiological surveillance of source animals and recipients. Novel infection control protocols may complement biosafety requirements. Infectious risks in xenotransplantation include both known human pathogens common to immunosuppressed organ recipients and from porcine organisms or xenozoonoses for which the clinical manifestations are less well defined and for which microbial assays and therapies are more limited. Some pig-specific organisms do not infect human cells but have systemic manifestations when active within the xenograft. The human risk posed by porcine endogenous retroviruses (PERV) is uncertain. There are no documented transmissions of PERV in humans and swine are available with inactivated genomic PERV loci. Metagenomic sequencing will complement more traditional diagnostic tools in the detection of any unknown pathogens in xenotransplantation recipients. Such data are required for the development of protocols for donor and recipient microbiological surveillance, infection control, and antimicrobial therapies that will enhance the safety of clinical xenotransplantation.

Leveraging Whole-Genome Resequencing to Uncover Genetic Diversity and Promote Conservation Strategies for Ruminants in Asia

Whole-genome resequencing (WGRS) is a critical branch of whole-genome sequencing (WGS), primarily targeting species with existing reference genomes. By aligning sequencing data to the reference genome, WGRS enables precise detection of genetic variations in individuals or populations. As a core technology in genomic research, WGS holds profound significance in ruminant studies. It not only reveals the intricate structure of ruminant genomes but also provides essential data for deciphering gene function, variation patterns, and evolutionary processes, thereby advancing the exploration of ruminant genetic mechanisms. However, WGS still faces several challenges, such as incomplete and inaccurate genome assembly, as well as the incomplete annotation of numerous unknown genes or gene functions. Although WGS can identify a vast number of genomic variations, the specific relationships between these variations and phenotypes often remain unclear, which limits its potential in functional studies and breeding applications. By performing WGRS on multiple samples, these assembly challenges can be effectively addressed, particularly in regions with high repeat content or complex structural variations. WGRS can accurately identify subtle variations among different individuals or populations and further elucidate their associations with specific traits, thereby overcoming the limitations of WGS and providing more precise genetic information for functional research and breeding applications. This review systematically summarizes the latest applications of WGRS in the analysis of ruminant genetic structures, genetic diversity, economic traits, and adaptive traits, while also discussing the challenges faced by this technology. It aims to provide a scientific foundation for the improvement and conservation of ruminant genetic resources.

Xenotransplantation in China: Past, Present, and Future

Organ failure poses a substantial global health challenge, and xenotransplantation emerges as one of the most promising avenues to mitigate the critical shortage of donor organs. In recent years, numerous research institutions have undertaken clinical and preclinical xenotransplantation in humans, instilling hope for notable progress. Nevertheless, formidable obstacles persist before success can be fully achieved. Chinese researchers have been at the forefront of xenotransplantation studies, actively contributing to several pivotal areas: the identification of critical genes essential for xenotransplantation and the creation of genetically modified pigs; preclinical studies on pig-to-nonhuman primate organ and tissue xenotransplantation, as well as the utilization of genetically engineered pig-derived biomaterials; contributions to both preclinical and clinical xenotransplantation research; and the formulation and refinement of xenotransplantation policies and ethical guidelines in China. In conclusion, this review seeks to not only acknowledge the contributions of Chinese researchers but also to encourage further collaboration between Chinese scholars and their international counterparts in advancing the field of xenotransplantation.

International Xenotransplantation Association (IXA) Position Paper on Infectious Disease Considerations in Xenotransplantation

Clinical xenotransplantation has the potential to address shortages of human organs for patients with end-stage organ failure. Advances in genetic engineering, immunosuppressive regimens, and infectious disease diagnostics have improved prospects for clinical xenotransplantation. Management of the infectious risks posed by clinical xenotransplantation requires biosecure breeding and validated methods for microbiological surveillance of source animals and recipients. Novel infection control protocols may complement biosafety requirements. Infectious risks in xenotransplantation include both known human pathogens common to immunosuppressed organ recipients and from porcine organisms or xenozoonoses for which the clinical manifestations are less well defined and for which microbial assays and therapies are more limited. Some pig-specific organisms do not infect human cells but have systemic manifestations when active within the xenograft. The human risk posed by porcine endogenous retroviruses (PERV) is uncertain. There are no documented transmissions of PERV in humans and swine are available with inactivated genomic PERV loci. Metagenomic sequencing will complement more traditional diagnostic tools in the detection of any unknown pathogens in xenotransplantation recipients. Such data are required for the development of protocols for donor and recipient microbiological surveillance, infection control, and antimicrobial therapies that will enhance the safety of clinical xenotransplantation.

Moving xenotransplantation from bench to bedside: Managing infectious risk

Xenotransplantation of organs from swine in immunosuppressed human recipients poses many of the same challenges of allotransplantation relative to the risk for infection, malignancy, or graft rejection in proportion to the degree of immunosuppression and epidemiologic exposures. The unique features of xenotransplantation from pigs relative to infectious risk center on the potential for unusual organisms derived from swine causing productive infection, "xenosis" or "xenozoonosis," in the host. Based on experience in allotransplantation, the greatest hazard is due to viruses, due to the relative lack of information regarding the behavior of these potential pathogens in humans, the absence of validated serologic and molecular assays for swine-derived pathogens, and uncertainty regarding the efficacy of therapeutic agents for these organisms. Other known, potential pathogens (i.e., bacteria, fungi, parasites) tend to be comparable to those of humans. Concerns remain for unknown organisms in swine that may replicate in immunosuppressed humans. Clinical trials of genetically modified organs sourced from swine in immunosuppressed humans with organ failure are under development. Such trials require informed consent regarding potential infectious risks to the recipient, determination of breeding characteristics of swine, assessments of potential risks to the public and healthcare providers, consideration of ethical issues posed by this novel therapy, and defined strategies to monitor and address infectious episodes that may be encountered by healthcare teams. Clinical trials in xenotransplantation will allow improved definition of potential infectious risks.