Lymphoproliferative Syndromes Associated with Human Herpesvirus-6A and Human Herpesvirus-6B

Bis-tridentate Iridium(III) Complex with the N-Heterocyclic Carbene Ligand as a Novel Efficient Electrochemiluminescence Emitter for the Sandwich Immunoassay of the HHV-6A Virus

Human herpesvirus type 6A (HHV-6A) can cause a series of immune and neurological diseases, and the establishment of a sensitive biosensor for the rapid detection of HHV-6A is of great significance for public health and safety. Herein, a bis-tridentate iridium complex (BisLT-Ir-NHC) comprising the N-heterocyclic carbene (NHC) ligand as a novel kind of efficient ECL luminophore has been unprecedently reported. Based on its excellent ECL properties, a new sensitive ECL-based sandwich immunosensor to detect the HHV-6A virus was successfully constructed by encapsulating BisLT-Ir-NHC into silica nanoparticles and embellishing ECL sensing interface with MXene@Au-CS. Notably, the immunosensor illustrated in this work not only had a wide linear range of 102 to 107 cps/μL but also showed outstanding recoveries (98.33-105.11%) in real human serum with an RSD of 0.85-3.56%. Undoubtedly, these results demonstrated the significant potential of the bis-tridentate iridium(III) complex containing an NHC ligand in developing ECL-based sensitive analytical methods for virus detection and exploring novel kinds of efficient iridium-based ECL luminophores in the future.

The Telomeric Repeats of HHV-6A Do Not Determine the Chromosome into Which the Virus Is Integrated

Human herpes virus 6A (HHV-6A) is able to integrate into the telomeric and subtelomeric regions of human chromosomes representing chromosomally integrated HHV-6A (ciHHV-6A). The integration starts from the right direct repeat (DRR) region. It has been shown experimentally that perfect telomeric repeats (pTMR) in the DRR region are required for the integration, while the absence of the imperfect telomeric repeats (impTMR) only slightly reduces the frequency of HHV-6 integration cases. The aim of this study was to determine whether telomeric repeats within DRR may define the chromosome into which the HHV-6A integrates. We analysed 66 HHV-6A genomes obtained from public databases. Insertion and deletion patterns of DRR regions were examined. We also compared TMR within the herpes virus DRR and human chromosome sequences retrieved from the Telomere-to-Telomere consortium. Our results show that telomeric repeats in DRR in circulating and ciHHV-6A have an affinity for all human chromosomes studied and thus do not define a chromosome for integration.

Disseminated Juvenile Xanthogranuloma and Hemophagocytic Lymphohistiocytosis Developed During Treatment of Acute Lymphoblastic Leukemia: Case Report

The association between acute lymphoblastic leukemia (ALL), non-Langerhans cell histiocytosis (non-LCH), and hemophagocytic lymphohistiocytosis (HLH), to the best of our knowledge, has not been published to date. Juvenile xanthogranuloma (JXG), as a type of non-LCH, is usually a benign disease limited to the skin. Systemic involvement is rarely reported. The present case report describes a 15-year-old boy diagnosed with disseminated JXG involving skin and bone marrow concurrent with severe symptoms of HLH during ALL therapy. Examination of immunoglobulin heavy chain genes in B-cell precursor leukemic blasts and histiocytes in the skin and bone marrow revealed identical rearrangements, confirming clonal relationship between both diseases. Implementation of corticosteroids, vinblastine, etoposide, cyclosporine, and tocilizumab resulted in partial skin lesion resolution with no improvement of bone marrow function; therefore, hematopoietic stem cell transplantation (HSCT) was eventually performed. The patient's hematological and general status has improved gradually; however, remarkable recovery of skin lesions was observed after empirical antitubercular therapy. Mycobacterium spp. infection should be considered as a possible secondary HLH trigger. Triple association of ALL, non-LCH, and HLH highlights heterogeneity of histiocytic disorders and possible common origin of dendritic and lymphoid cells.

Humanization of Murine Neutralizing Antibodies against Human Herpesvirus 6B

Exanthem subitum is a common childhood illness caused by primary infection with human herpesvirus 6B (HHV-6B). It is occasionally complicated by febrile seizures and even encephalitis. HHV-6B reactivation also causes encephalitis, especially after allogeneic hematopoietic stem cell transplantation. However, no adequate antiviral treatment for HHV-6B has yet been established. Mouse-derived monoclonal antibodies (MAbs) against the HHV-6B envelope glycoprotein complex gH/gL/gQ1/gQ2 have been shown to neutralize the viral infection. These antibodies have the potential to become antiviral agents against HHV-6B despite their inherent immunogenicity to the human immune system. Humanization of MAbs derived from other species is one of the proven solutions to such a dilemma. In this study, we constructed chimeric forms of two neutralizing MAbs against HHV-6B to make humanized antibodies. Both showed neutralizing activities equivalent to those of their original forms. This is the first report of humanized antibodies against HHV-6B and provides a basis for the further development of HHV-6B-specific antivirals.IMPORTANCE Human herpesvirus 6B (HHV-6B) establishes lifelong latent infection in most individuals after the primary infection. Encephalitis is the most severe complication caused by both the primary infection and the reactivation of HHV-6B and is the cause of considerable mortality in patients, without any established treatments to date. The humanization of the murine neutralizing antibodies described in this research provided a feasible way to reduce the inherent immunogenicity of the antibodies without changing their neutralizing activities. These newly designed chimeric antibodies against HHV-6B have the potential to be candidates for antivirals for future use.

The Importance of the Autopsy in Medicine: Perspectives of Pathology Colleagues

This article presents a perspective on the importance of the autopsy in medical practice and science based on experiences of the authors as physician-scientists involved in autopsy practice. Our perspectives are presented on the seminal contributions of the autopsy in the areas of cardiovascular disease, including congenital heart disease, atherosclerosis, coronary artery disease, and myocardial infarction, and infectious disease, including tuberculosis and viral infections. On the positive side of the future of the autopsy, we discuss the tremendous opportunities for important research to be done by application of advanced molecular biological techniques to formalin-fixed, paraffin-embedded tissue blocks obtained at autopsy. We also note with concern the countervailing forces impacting the influence of pathology in education and clinical practice at our academic medical centers, which also present impediments to increasing autopsy rates. Our challenge as academic pathologists, whose careers have been molded by involvement in the autopsy, is to counter these trends. The challenges are great but the benefits for medicine and society are enormous.

Human Herpesvirus 6 and Malignancy: A Review

In order to determine the role of human herpesvirus 6 (HHV-6) in human disease, several confounding factors, including methods of detection, types of controls, and the ubiquitous nature of the virus, must be considered. This is particularly problematic in the case of cancer, in which rates of detection vary greatly among studies. To determine what part, if any, HHV-6 plays in oncogenesis, a review of the literature was performed. There is evidence that HHV-6 is present in certain types of cancer; however, detection of the virus within tumor cells is insufficient for assigning a direct role of HHV-6 in tumorigenesis. Findings supportive of a causal role for a virus in cancer include presence of the virus in a large proportion of cases, presence of the virus in most tumor cells, and virus-induced in-vitro cell transformation. HHV-6, if not directly oncogenic, may act as a contributory factor that indirectly enhances tumor cell growth, in some cases by cooperation with other viruses. Another possibility is that HHV-6 may merely be an opportunistic virus that thrives in the immunodeficient tumor microenvironment. Although many studies have been carried out, it is still premature to definitively implicate HHV-6 in several human cancers. In some instances, evidence suggests that HHV-6 may cooperate with other viruses, including EBV, HPV, and HHV-8, in the development of cancer, and HHV-6 may have a role in such conditions as nodular sclerosis Hodgkin lymphoma, gastrointestinal cancer, glial tumors, and oral cancers. However, further studies will be required to determine the exact contributions of HHV-6 to tumorigenesis.