Excision of Integrated Human Herpesvirus 6A Genomes Using CRISPR/Cas9 Technology.

Human herpesviruses 6A and 6B are betaherpesviruses that can integrate their genomes into the telomeres of latently infected cells. Integration can also occur in germ cells, resulting in individuals who harbor the integrated virus in every cell of their body and can pass it on to their offspring. This condition is termed inherited chromosomally integrated HHV-6 (iciHHV-6) and affects about 1% of the human population.

Visualization of Marek's Disease Virus Genomes in Living Cells during Lytic Replication and Latency.

Visualization of the herpesvirus genomes during lytic replication and latency is mainly achieved by fluorescence in situ hybridization (FISH). Unfortunately, this technique cannot be used for the real-time detection of viral genome in living cells. To facilitate the visualization of the Marek's disease virus (MDV) genome during all stages of the virus lifecycle, we took advantage of the well-established tetracycline operator/repressor (TetO/TetR) system.

Unbiased optical mapping of telomere-integrated endogenous human herpesvirus 6.

Next-generation sequencing technologies allowed sequencing of thousands of genomes. However, there are genomic regions that remain difficult to characterize, including telomeres, centromeres, and other low-complexity regions, as well as transposable elements and endogenous viruses. Human herpesvirus 6A and 6B (HHV-6A and HHV-6B) are closely related viruses that infect most humans and can integrate their genomes into the telomeres of infected cells.

Evolutionary History of Endogenous Human Herpesvirus 6 Reflects Human Migration out of Africa.

Human herpesvirus 6A and 6B (HHV-6) can integrate into the germline, and as a result, ∼70 million people harbor the genome of one of these viruses in every cell of their body. Until now, it has been largely unknown if 1) these integrations are ancient, 2) if they still occur, and 3) whether circulating virus strains differ from integrated ones. Here, we used next-generation sequencing and mining of public human genome data sets to generate the largest and most diverse collection of circulating and integrated HHV-6 genomes studied to date.

Abrogation of Marek's disease virus replication using CRISPR/Cas9.

Marek's disease virus (MDV) is a highly cell-associated alphaherpesvirus that causes deadly lymphomas in chickens. While vaccination protects against clinical symptoms, MDV field strains can still circulate in vaccinated flocks and continuously evolve towards greater virulence. MDV vaccines do not provide sterilizing immunity, allowing the virus to overcome vaccine protection, and has increased the need for more potent vaccines or alternative interventions.

Chromatin Profiles of Chromosomally Integrated Human Herpesvirus-6A.

Human herpesvirus-6A (HHV-6A) and 6B (HHV-6B) are two closely related betaherpesviruses that are associated with various diseases including seizures and encephalitis. The HHV-6A/B genomes have been shown to be present in an integrated state in the telomeres of latently infected cells. In addition, integration of HHV-6A/B in germ cells has resulted in individuals harboring this inherited chromosomally integrated HHV-6A/B (iciHHV-6) in every cell of their body.

The Role of Marek's Disease Virus UL12 and UL29 in DNA Recombination and the Virus Lifecycle.

Marek's disease virus (MDV) is an oncogenic alphaherpesvirus that infects chickens and integrates its genome into the telomeres of latently infected cells. MDV encodes two proteins, UL12 and UL29 (ICP8), that are conserved among herpesviruses and could facilitate virus integration. The orthologues of UL12 and UL29 in herpes simplex virus 1 (HSV-1) possess exonuclease and single strand DNA-binding activity, respectively, and facilitate DNA recombination; however, the role of both proteins in the MDV lifecycle remains elusive.

Viral Proteins U41 and U70 of Human Herpesvirus 6A Are Dispensable for Telomere Integration.

Human herpesvirus-6A and -6B (HHV-6A and -6B) are two closely related betaherpesviruses that infect humans. Upon primary infection they establish a life-long infection termed latency, where the virus genome is integrated into the telomeres of latently infected cells. Intriguingly, HHV-6A/B can integrate into germ cells, leading to individuals with inherited chromosomally-integrated HHV-6 (iciHHV-6), who have the HHV-6 genome in every cell.

The ND10 Complex Represses Lytic Human Herpesvirus 6A Replication and Promotes Silencing of the Viral Genome.

Human herpesvirus 6A (HHV-6A) replicates in peripheral blood mononuclear cells (PBMCs) and various T-cell lines in vitro. Intriguingly, the virus can also establish latency in these cells, but it remains unknown what influences the decision between lytic replication and the latency of the virus. Incoming virus genomes are confronted with the nuclear domain 10 (ND10) complex as part of an intrinsic antiviral response.

A Novel Antimicrobial Coating Represses Biofilm and Virulence-Related Genes in Methicillin-Resistant .

Methicillin-resistant (MRSA) has become an important cause of hospital-acquired infections worldwide. It is one of the most threatening pathogens due to its multi-drug resistance and strong biofilm-forming capacity. Thus, there is an urgent need for novel alternative strategies to combat bacterial infections.

Telomeres and Telomerase: Role in Marek's Disease Virus Pathogenesis, Integration and Tumorigenesis.

Telomeres protect the ends of vertebrate chromosomes from deterioration and consist of tandem nucleotide repeats (TTAGGG) that are associated with a number of proteins. Shortening of the telomeres occurs during genome replication, thereby limiting the replication potential of somatic cells. To counteract this shortening, vertebrates encode the telomerase complex that maintains telomere length in certain cell types via de novo addition of telomeric repeats.

The N-terminus of murine leukaemia virus p12 protein is required for mature core stability.

The murine leukaemia virus (MLV) gag gene encodes a small protein called p12 that is essential for the early steps of viral replication. The N- and C-terminal regions of p12 are sequentially acting domains, both required for p12 function. Defects in the C-terminal domain can be overcome by introducing a chromatin binding motif into the protein.

The gammaretroviral p12 protein has multiple domains that function during the early stages of replication.

Background: The Moloney murine leukaemia virus (Mo-MLV) gag gene encodes three main structural proteins, matrix, capsid and nucleocapsid and a protein called p12. In addition to its role during the late stages of infection, p12 has an essential, but undefined, function during early post-entry events. As these stages of retroviral infection remain poorly understood, we set out to investigate the function of p12.

Molecular model of prion transmission to humans.

To assess interspecies barriers to transmission of transmissible spongiform encephalopathies, we investigated the ability of disease-associated prion proteins (PrPd) to initiate conversion of the human normal cellular form of prion protein of the 3 major PRNP polymorphic variants in vitro. Protein misfolding cyclic amplification showed that conformation of PrPd partly determines host susceptibility.

Human platelets as a substrate source for the in vitro amplification of the abnormal prion protein (PrP) associated with variant Creutzfeldt-Jakob disease.

Background: Four recent cases of transfusion-related transmission of variant Creutzfeldt-Jakob disease (vCJD) highlight the need to develop a highly sensitive and specific screening test to detect infectivity in the blood of asymptomatic infected individuals. Protein misfolding cyclic amplification (PMCA), a method for the amplification of minute amounts of disease-associated abnormal prion protein (PrP(Sc)) to readily detectable levels, could be incorporated into such a test provided that a suitable substrate source for routine use in human PMCA reactions can be found.

Study Design And Methods: With the use of seed sources from individuals with variant and sporadic CJD, the use of human platelets (PLTs) as a PMCA substrate source was evaluated.

Effects of human PrPSc type and PRNP genotype in an in-vitro conversion assay.

Prion protein type and codon 129 genotype are thought to be major determinants of susceptibility and phenotype in human prion diseases. Using an in-vitro system (protein misfolding cyclic amplification) we have attempted to model human prion protein conversion using the abnormal prion protein associated with each of the major sporadic Creutzfeldt-Jakob disease subtypes, in substrates containing the normal cellular form of the prion protein of each of the three possible human PRNP codon 129 polymorphic genotypes. The prion protein type is converted with fidelity in these amplification reactions, but the efficiency of conversion depends both on the methionine/valine polymorphic status of the sporadic Creutzfeldt-Jakob disease seed and substrate homogenate, and on the abnormal prion protein type.

An antibody to the aggregated synthetic prion protein peptide (PrP106-126) selectively recognizes disease-associated prion protein (PrP) from human brain specimens.

Human prion diseases are characterized by the conversion of the normal host cellular prion protein (PrP(C)) into an abnormal misfolded form [disease-associated prion protein (PrP(Sc))]. Antibodies that are capable of distinguishing between PrP(C) and PrP(Sc) may prove to be useful, not only for the diagnosis of these diseases, but also for a better understanding of the molecular mechanisms involved in disease pathogenesis. In an attempt to produce such antibodies, we immunized mice with an aggregated peptide spanning amino acid residues 106 to 126 of human PrP (PrP106-126).