Adeno-Associated Virus Delivery of Anti-HIV Monoclonal Antibodies Can Drive Long-Term Virologic Suppression.

Long-term delivery of anti-HIV monoclonal antibodies (mAbs) using adeno-associated virus (AAV) vectors holds promise for the prevention and treatment of HIV infection. We describe a therapy trial in which four rhesus monkeys were infected with SHIV-AD8 for 86 weeks before receiving the AAV-encoded mAbs 3BNC117, 10-1074, and 10E8. Although anti-drug antibody (ADA) responses restricted mAb delivery, one monkey successfully maintained 50-150 µg/mL of 3BNC117 and 10-1074 for over 2 years. Delivery of these two mAbs to this monkey resulted in an abrupt decline in plasma viremia, which remained undetectable for 38 successive measurements over 3 years. We generated two more examples of virologic suppression using AAV delivery of a cocktail of four mAbs in a 12-monkey study. Our results provide proof of concept for AAV-delivered mAbs to produce a "functional cure." However, they also serve as a warning that ADAs may be a problem for practical application of this approach in humans.

Identification and characterization of a long non-coding RNA up-regulated during HIV-1 infection.

Long non-coding RNAs (lncRNAs) are rapidly emerging as important regulators of a diverse array of cellular functions. Here, we describe a meta-analysis of two independent RNA-seq studies to identify lncRNAs that are differentially expressed upon HIV-1 infection. Only three lncRNA genes exhibited altered expression of ≥ 2-fold in HIV-1-infected cells. Of these, the uncharacterized lncRNA LINC00173 was chosen for further study. Both transcript variants of LINC00173 (lnc173 TSV1 and 2) could be detected by qPCR, localized predominantly to the nucleus and were reproducibly up-regulated during infection. Knock-out of the LINC00173 locus did not have detectable effects on HIV-1 replication. Interestingly, however, stimulation of Jurkat T cells with PMA/ionomycin resulted in a decrease of lnc173 expression, and Jurkat cells deficient for lnc173 on average expressed higher levels of specific cytokines than control cells. These data suggest that lnc173 may have a role in the regulation of cytokines in T cells.

Latency, Integration, and Reactivation of Human Herpesvirus-6.

Human herpesvirus-6A (HHV-6A) and human herpesvirus-6B (HHV-6B) are two closely related viruses that infect T-cells. Both HHV-6A and HHV-6B possess telomere-like repeats at the terminal regions of their genomes that facilitate latency by integration into the host telomeres, rather than by episome formation. In about 1% of the human population, human herpes virus-6 (HHV-6) integration into germline cells allows the viral genome to be passed down from one generation to the other; this condition is called inherited chromosomally integrated HHV-6 (iciHHV-6). This review will cover the history of HHV-6 and recent works that define the biological differences between HHV-6A and HHV-6B. Additionally, HHV-6 integration and inheritance, the capacity for reactivation and superinfection of iciHHV-6 individuals with a second strain of HHV-6, and the role of hypomethylation of human chromosomes during integration are discussed. Overall, the data suggest that integration of HHV-6 in telomeres represent a unique mechanism of viral latency and offers a novel tool to study not only HHV-6 pathogenesis, but also telomere biology. Paradoxically, the integrated viral genome is often defective especially as seen in iciHHV-6 harboring individuals. Finally, gaps in the field of HHV-6 research are presented and future studies are proposed.

Persistent human herpesvirus-6 infection in patients with an inherited form of the virus.

Human herpesvirus-6 (HHV-6)A and 6B are ubiquitous betaherpesviruses viruses with lymphotropic and neurotropic potential. As reported earlier, these viruses establish latency by integration into the telomeres of host chromosomes. Chromosomally integrated HHV-6 (CIHHV-6) can be transmitted vertically from parent to child. Some CIHHV-6 patients are suffering from neurological symptoms, while others remain asymptomatic. Four patients with CIHHV-6 and CNS dysfunction were treated with valganciclovir or foscarnet. HHV-6 replication was detected by reverse transcriptase polymerase chain reaction amplification of a late envelope glycoprotein. In this study we also compared the inherited and persistent HHV-6 viruses by DNA sequencing. The prevalence of CIHHV-6 in this cohort of adult patients from the USA suffering from a wide range of neurological symptoms including long-term fatigue were found significantly greater than the reported 0.8% in the general population. Long-term antiviral therapy inhibited HHV-6 replication as documented by loss of viral mRNA production. Sequence comparison of the mRNA and the inherited viral genome revealed that the transcript is produced by an exogenous virus. In conclusion, the data presented here document that some individuals with CIHHV-6 are infected persistently with exogenous HHV-6 strains that lead to a wide range of neurological symptoms; the proposed name for this condition is inherited herpesvirus 6 syndrome or IHS.

Mapping the telomere integrated genome of human herpesvirus 6A and 6B.

Human herpesvirus 6B (HHV-6B) is the causative agent of roseola infantum. HHV-6A and 6B can reactivate in immunosuppressed individuals and are linked with severe inflammatory response, organ rejection and central nervous system diseases. About 0.85% of the US and UK population carries an integrated HHV-6 genome in all nucleated cells through germline transmission. We have previously reported that the HHV-6A genome integrated in telomeres of patients suffering from neurological dysfunction and also in telomeres of tissue culture cells. We now report that HHV-6B also integrates in telomeres during latency. Detailed mapping of the integrated viral genomes demonstrates that a single HHV-6 genome integrates and telomere repeats join the left end of the integrated viral genome. When HEK-293 cells carrying integrated HHV-6A were exposed to the histone deacetylase inhibitor Trichostatin A, circularization and/or formation of concatamers were detected and this assay could be used to distinguish between lytic replication and latency.

Epigenetic regulation of Kaposi's sarcoma-associated herpesvirus replication.

Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent of Kaposi's sarcoma and B-lymphocyte disorders, primary effusion lymphoma (PEL) and Multicentric Castleman's Disease (MCD). KSHV usually exists in a latent form in which the viral genome is circularized into an extrachormosomal episome. However, induction of lytic replication by environmental stimuli or chemical agents is important for the spread of KSHV. The switch between latency and lytic replication is regulated by epigenetic factors. Hypomethylation of the promoter of replication and transcription activator (RTA), which is essential for the lytic switch, leads to KSHV reactivation. Histone acetylation induces KSHV replication by influencing protein-protein-associations and transcription factor binding. Histone modifications also determine chromatin structure and nucleosome positioning, which are important for KSHV DNA replication during latency. The association of KSHV proteins with chromatin remodeling complexes promotes the open chromatin structure needed for transcription factor binding and DNA replication. Additionally, post-translational modification of KSHV proteins is important for the regulation of RTA activity and KSHV replication. KSHV may also cause epigenetic modification of the host genome, contributing to promoter hypermethylation of tumor suppressor genes in KSHV-associated neoplasias.