Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disorder characterized by features reminiscent of marked premature ageing. Here, we present evidence of mutations in lamin A (LMNA) as the cause of this disorder. The HGPS gene was initially localized to chromosome 1q by observing two cases of uniparental isodisomy of 1q-the inheritance of both copies of this material from one parent-and one case with a 6-megabase paternal interstitial deletion. Sequencing of LMNA, located in this interval and previously implicated in several other heritable disorders, revealed that 18 out of 20 classical cases of HGPS harboured an identical de novo (that is, newly arisen and not inherited) single-base substitution, G608G(GGC > GGT), within exon 11. One additional case was identified with a different substitution within the same codon. Both of these mutations result in activation of a cryptic splice site within exon 11, resulting in production of a protein product that deletes 50 amino acids near the carboxy terminus. Immunofluorescence of HGPS fibroblasts with antibodies directed against lamin A revealed that many cells show visible abnormalities of the nuclear membrane. The discovery of the molecular basis of this disease may shed light on the general phenomenon of human ageing.

Translational fidelity, essential for protein and cell function, requires accurate tRNA aminoacylation. Purified aminoacyl-tRNA synthetases exhibit a fidelity of 1 error per 10,000 to 100,000 couplings 1, 2. The accuracy of tRNA aminoacylation in vivo is uncertain, however, and might be considerably lower 3–6. Here, we show that in mammalian cells, approximately 1% of methionine (Met) residues used in protein synthesis are aminoacylated to non-methionyl-tRNAs. Remarkably, Met-misacylation increases up to 10-fold upon exposing cells to live or non-infectious viruses, toll-like receptor ligands, or chemically induced oxidative stress. Met is misacylated to specific non-methionyl-tRNA families, and these Met-misacylated tRNAs are used in translation. Met-misacylation is blocked by an inhibitor of cellular oxidases, implicating reactive oxygen species (ROS) as the misacylation trigger. Among six amino acids tested, tRNA misacylation occurs exclusively with Met. As Met residues are known to protect proteins against ROS-mediated damage 7, we propose that Met-misacylation functions adaptively to increase Met incorporation into proteins to protect cells against oxidative stress. In demonstrating an unexpected conditional aspect of decoding mRNA, our findings illustrate the importance of considering alternative iterations of the genetic code.

The COVID-19 pandemic, caused by infection with the SARS-CoV-2 coronavirus, is having a deleterious impact on health services and the global economy, highlighting the urgent need for an effective vaccine. Such a vaccine would need to rapidly confer protection after one or two doses and would need to be manufactured using components suitable for scale-up. Here, we developed an alphavirus-derived replicon RNA vaccine candidate, repRNA-CoV2S, encoding the SARS-CoV-2 spike (S) protein. The RNA replicons were formulated with Lipid InOrganic Nanoparticles (LION) that were designed to enhance vaccine stability, delivery, and immunogenicity. We show that a single intramuscular injection of the LION/repRNA-CoV2S vaccine in mice elicited robust production of anti-SARS-CoV-2 S protein IgG antibody isotypes indicative of a Type 1 T helper cell response. A prime/boost regimen induced potent T cell responses in mice including antigen-specific responses in lung and spleen. Prime-only immunization of aged (17-month old) mice induced smaller immune responses compared to young mice, but this difference was abrogated by booster immunization. Importantly, in nonhuman primates, prime-only immunization in one intramuscular injection site or prime/boost immunizations in 5 intramuscular injection sites elicited modest T cell responses and robust antibody responses. The antibody responses persisted for at least 70 days and neutralized SARS-CoV-2 at titers comparable to those in human serum samples collected from individuals convalescing from COVID-19. These data support further development of LION/repRNA-CoV2S as a vaccine candidate for prophylactic protection against SARS-CoV-2 infection.

BackgroundHuntington's disease (HD) is a fatal inherited neurodegenerative disease, caused by a

"Cross-priming" describes the activation of naïve CD8+ T cells by professional antigen-presenting cells that have acquired viral or tumor antigens from "donor" cells. Antigen transfer is believed to be mediated by donor cell-derived molecular chaperones bearing short peptide ligands generated by proteasome degradation of protein antigens. We show here that cross-priming is based on the transfer of proteasome substrates rather than peptides. These findings are potentially important for the rational design of vaccines that elicit CD8+ T cell responses.

In the recently developed Semliki Forest virus (SFV) DNA expression system, recombinant RNA encoding the viral replicase, and helper RNA molecules encoding the structural proteins needed for virus assembly are cotransfected into cells. Since the helper RNA lacks the sequence needed for its packaging into nucleocapsids, only recombinant RNAs should be packaged. We have found, however, that small amounts of replication-proficient SFV particles can still be produced. Here we describe the construction of a helper variant with a mutation in the gene encoding the viral spike protein such that its product cannot undergo normal proteolytic processing to activate viral entry functions. Hence, the recombinant stock is noninfectious, but may be activated by cleavage with chymotrypsin. When recombinant virus produced with the new helper was examined in a variety of assays, including sensitive animal tests, we were unable to detect any replication-competent SFV particles. We therefore conclude that this conditional expression system meets extremely stringent biosafety requirements.

Mental fatigue after MTBI can last for several years. It can be profoundly disabling and affect working capacity as well as social activities. Subjective mental fatigue following brain injury is suggested to mainly correlate with objectively measured information processing speed.

We describe a DNA vaccine strategy that allows antigens to be produced in vivo in the context of an alphaviral replicon. Mice immunized with such vectors developed humoral and cellular immune responses at higher levels than mice that received a conventional DNA vaccine vector. Immunized animals acquired protective immunity to lethal influenza challenge. Compared with traditional DNA vaccine strategies in which vectors are persistent and the expression constitutive, the expression mediated by the alphaviral vector was transient and lytic. As a result, biosafety risks such as chromosomal integration, and the induction of immunological tolerance, could be circumvented.