Transmission of hepatitis B virus through allotransplantation

Infectious Disease Transmission in Solid Organ Transplantation: Donor Evaluation, Recipient Risk, and Outcomes of Transmission

In 2016, the Transplantation Society of Australia and New Zealand, with the support of the Australian Government Organ and Tissue authority, commissioned a literature review on the topic of infectious disease transmission from deceased donors to recipients of solid organ transplants. The purpose of this review was to synthesize evidence on transmission risks, diagnostic test characteristics, and recipient management to inform best-practice clinical guidelines. The final review, presented as a special supplement in Transplantation Direct, collates case reports of transmission events and other peer-reviewed literature, and summarizes current (as of June 2017) international guidelines on donor screening and recipient management. Of particular interest at the time of writing was how to maximize utilization of donors at increased risk for transmission of human immunodeficiency virus, hepatitis C virus, and hepatitis B virus, given the recent developments, including the availability of direct-acting antivirals for hepatitis C virus and improvements in donor screening technologies. The review also covers emerging risks associated with recent epidemics (eg, Zika virus) and the risk of transmission of nonendemic pathogens related to donor travel history or country of origin. Lastly, the implications for recipient consent of expanded utilization of donors at increased risk of blood-borne viral disease transmission are considered.

Liver transplantation in the 21st century: expanding the donor options

Over the past decade, use of ECD organs for OLT has allowed many transplant programs to afford patients access to an otherwise scarce resource and to maintain center volume. Although overall posttransplant outcomes are inferior to results with optimal, whole-liver grafts, aggressive utilization of ECD and DCD organs significantly lowers median wait-times for OLT, MELD score at OLT, and death while awaiting transplantation. It is incumbent on the transplant community to provide continued scrutiny of the many factors involved in ECD organ utilization, evaluate the degree of risk and benefit such allografts may impart on particular recipients, and thereby provide suitable “matching” to maximize favorable outcomes. Transplant caregivers need to provide patients with evidence-based care decisions, be good stewards of a scarce resource, and maintain threshold survival results for their programs. This requires balancing the urgency with which a transplant is needed and the utility of such a transplant. There is a clear necessity to pursue additional donor research to improve use of these marginal grafts and assess interventions that enhance the safety of ECD livers.

Optimal utilization of extended hepatic grafts

Orthotopic liver transplantation has emerged as the standard treatment for end-stage liver disease. In the United States, the number of listed patients has tripled in the last two decades. Organ availability during the same period has plateaued at approximately 6000 grafts annually, resulting in a fivefold increase in wait-list mortality. The problem is not specific to the United States; European and Asian registries report similar shortages. Donor pool expansion strategies such as the use of living donors, cadaveric split livers, and "extended criteria donors"; (ECD) are being pursued. Used judiciously, ECD grafts provide an opportunity for addressing the shortage. Although there is no universally accepted definition of ECD, the term generally refers to donor factors predisposing recipients to poor initial graft function and/or increased long-term risk. These factors include advanced donor age, hypernatremia, prolonged warm ischemic time, pressor requirement, and donation after cardiac death. The transplant community is scrutinizing all factors to evaluate the degree of risk they impart on the recipient and the extent to which grafts can be "matched"; to maintain acceptable outcomes. We review the importance of selected factors and the impact of a "matching"; strategy to minimize recipient risk while optimizing graft use.

The power and the limitations of cross-species protein identification by mass spectrometry-driven sequence similarity searches

Mass spectrometry-driven BLAST (MS BLAST) is a database search protocol for identifying unknown proteins by sequence similarity to homologous proteins available in a database. MS BLAST utilizes redundant, degenerate, and partially inaccurate peptide sequence data obtained by de novo interpretation of tandem mass spectra and has become a powerful tool in functional proteomic research. Using computational modeling, we evaluated the potential of MS BLAST for proteome-wide identification of unknown proteins. We determined how the success rate of protein identification depends on the full-length sequence identity between the queried protein and its closest homologue in a database. We also estimated phylogenetic distances between organisms under study and related reference organisms with completely sequenced genomes that allow substantial coverage of unknown proteomes.

The use of direct cDNA selection to rapidly and effectively identify genes in the fungus Aspergillus fumigatus

Aspergillus fumigatus is one of the causes of invasive lung disease in immunocompromised individuals. To rapidly identify genes in this fungus, including potential targets for chemotherapy, diagnostics, and vaccine development, we constructed cDNA libraries. We began with non-normalized libraries, then to improve this approach we constructed a normalized cDNA library using direct cDNA selection. Normalization resulted in a reduction of the frequency of clones with highly expressed genes and an enrichment of underrepresented cDNAs. Expressed sequence tags generated from both the original and the normalized libraries were compared with the genomes of Saccharomyces cerevisiae, Schizosaccharomyces pombe, and Candida albicans, indicating that a large proportion of A. fumigatus genes do not have orthologs in these fungal species. This method allowed the expeditious identification of genes in a fungal pathogen. The same approach can be applied to other human or plant pathogens to rapidly identify genes without the need for genomic sequence information.

Isolation of a mouse brain cDNA expressed in developing neuroblasts and mature neurons

A previously uncharacterized 4.5-kb mouse cDNA clone, designated mc7, was isolated and found to be predominantly expressed in brain. This cDNA predicts a 1035-bp open reading frame that encodes for a 345-amino acid polypeptide especially rich in glutamic acid residues located in the region from residues 80 to 174. Computational analysis revealed among other features, putative zinc-finger motifs and coiled-coil regions. The corresponding mc7 gene is detected in mouse, rat, pig and human genomes. In mouse the mc7 mRNA is expressed predominantly in brain and to a much lesser extent in kidney, lung and spleen. In brain it is detectable as early as embryonic day 14 while it is retained in the adult. In situ hybridization studies revealed that mc7 mRNA is widely, albeit unevenly, expressed in neurons throughout the adult brain. Developmental in situ hybridization studies in the cerebellar cortex demonstrated that at postnatal day 5 mc7 mRNA is mainly expressed in neuroblasts of the external granular layer and in developing neurons of the internal granular layer. Some staining is also present in purkinje cells becoming particularly pronounced at postnatal day 10, the time of arborarization of their dendritic tree. In the adult cerebellar cortex expression is mainly confined in purkinje cells and to a lesser extent in granule neurons. The early expression of mc7 in neuroblasts and developing neurons as well as its retention in a wide variety of mature neurons suggest that it may play a role in the process of differentiation and maturation of these cells in the brain.