ber of a new arsenite methyltransferase type, exclusively present in the Thermus genus. The enzyme methylates arsenite-producing MMAs and DMAs. Furthermore, we developed an hyperthermophilic Cas9-based genome-editing tool, active up to 65°C. The tool allowed us to perform highly efficient, marker-free modifications (either gene deletion or insertion) in the T. thermophilus genome. With these modifications, we confirmed the critical role of TtArsM in the arsenite detoxification system and developed a sensitive whole-cell bioreporter for arsenic ions. We anticipate that the developed tool can be easily adapted for editing the genomes of other thermophilic bacteria, significantly boosting fundamental and metabolic engineering in hyperthermophilic microorganisms.Human immunodeficiency virus type 1 (HIV-1) Gag selects and packages the HIV RNA genome during virus assembly. However, HIV-1 RNA constitutes only a small fraction of the cellular RNA. Although Gag exhibits a slight preference to viral RNA, most of the cytoplasmic Gag proteins are associated with cellular RNAs. Thus, it is not understood how HIV-1 achieves highly efficient genome packaging. We hypothesize that besides RNA binding, other properties of Gag are important for genome packaging. Many Gag mutants have assembly defects that preclude analysis of their effects on genome packaging. To bypass this challenge, we established complementation systems that separate the particle-assembling and RNA-binding functions of Gag we used a set of Gag proteins to drive particle assembly and an RNA-binding Gag to package HIV-1 RNA. We have developed two types of RNA-binding Gag in which packaging is mediated by the authentic nucleocapsid (NC) domain or by a nonviral RNA-binding domain. We found that in both cases, mutatnchor at the plasma membrane are critical for genome packaging. Our results revealed that Gag needs to multimerize on viral RNA at the plasma membrane in order to package RNA genome.To identify novel host factors as putative targets to reverse HIV-1 latency, we performed an insertional mutagenesis genetic screen in a latent HIV-1 infected pseudohaploid KBM7 cell line (Hap-Lat). Following mutagenesis, insertions were mapped to the genome, and bioinformatic analysis resulted in the identification of 69 candidate host genes involved in maintaining HIV-1 latency. A select set of candidate genes was functionally validated using short hairpin RNA (shRNA)-mediated depletion in latent HIV-1 infected J-Lat A2 and 11.1 T cell lines. We confirmed ADK, CHD9, CMSS1, EVI2B, EXOSC8, FAM19A, GRIK5, IRF2BP2, NF1, and USP15 as novel host factors involved in the maintenance of HIV-1 latency. Chromatin immunoprecipitation assays indicated that CHD9, a chromodomain helicase DNA-binding protein, maintains HIV-1 latency via direct association with the HIV-1 5′ long terminal repeat (LTR), and its depletion results in increased histone acetylation at the HIV-1 promoter, concomitant with HIV-1 latency reversal. Five strategies which aim to promote clearance of the infected cells. Using a two-color haploid screen, we identified 69 candidate genes as latency-maintaining host factors and functionally validated a subset of 10 of those in additional T-cell-based cell line models of HIV-1 latency. We further demonstrated that CHD9 is associated with HIV-1’s promoter, the 5′ LTR, while this association is lost upon reactivation. Additionally, we characterized the latency reversal potential of FDA compounds targeting ADK, NF1, and GRIK5 and identify the GRIK5 inhibitor topiramate as a viable latency reversal agent with clinical potential.Circular RNAs (circRNAs) are a new class of noncoding RNAs that have gained increased attention. DNA virus infections have been reported to induce modifications in cellular circRNA transcriptomes and express viral circRNAs. However, the identification and expression of cellular and viral circRNAs are unknown in the context of respiratory syncytial virus (RSV), a human RNA virus with no effective treatments or vaccines. Here, we report a comprehensive identification of the cellular and viral circRNAs induced by RSV infection in A549 cells with high-throughput sequencing. In total, 53,719 cellular circRNAs and 2,280 differentially expressed cellular circRNAs were identified. Trend analysis further identified three significant expression pattern clusters, which were related to the antiviral immune response according to gene enrichment analysis. Subsequent results showed that not only RSV infection but also poly(I·C) treatment and another RNA virus infection induced the upregulation of the top 10 circRNAs from thexpress viral circRNAs. However, the identification and expression of cellular and viral circRNAs are unknown in the context of respiratory syncytial virus (RSV), a human RNA virus with no effective treatments or vaccines. Here, we report a comprehensive identification of the cellular and viral circRNAs induced by RSV infection by high-throughput sequencing. We revealed that RSV infection induces the differential expression of cellular circRNAs, some of which affected RSV infection, and that RSV also expresses viral circRNAs. Our study reveals novel layers of host-RSV interactions and identifies cellular or viral circRNAs that may be novel therapeutic targets or biomarkers.Human influenza viruses evade host immune responses by accumulating mutations around the receptor-binding region of the hemagglutinin (HA) protein, which is composed of three key elements, the 130-loop, the 190-helix, and the 220-loop. Here, we characterized two human H3N2 influenza viruses with 12- and 16-amino acid deletions around the HA receptor-binding site that were isolated after antigenic selection of mutated H3N2 viruses. Structural modeling suggested that the 12-amino acid deletion eliminated the 190-helix. The 16-amino acid deletion comprises two stretches of 11- and 5-amino acid deletions. As the result of a frameshift, “novel” amino acids (not found in wild-type HA at these positions) are encoded between the deleted regions. Interestingly, structural modeling predicted that the novel sequence forms a structure resembling the 190-helix. However, compared to wild-type HA, the 16-amino acid deletion mutant lacks two antiparallel beta-sheets that connect the 190-helix and the 220-loop in wild-type HAultured cells, 12- and 16-amino acid deletion mutants were attenuated, and the 16-amino acid deletion mutant replicated in Syrian hamsters. Compared with wild-type virus, both mutants showed changes in their reactivity to some of the sera tested and changes in their binding affinity to sialic acids, which serve as influenza virus receptors. Collectively, our findings highlight the plasticity of HA.Mice immunized with a combination of an adenovirus vector (Ad5-YFV) and live-attenuated (LMA)-based vaccines were evaluated for protective efficacy against pneumonic plague. While the Ad5-YFV vaccine harbors a fusion cassette of three genes encoding YscF, F1, and LcrV, LMA represents a mutant of parental Yersinia pestis CO92 deleted for genes encoding Lpp, MsbB, and Ail. Ad5-YFV and LMA were either administered simultaneously (1-dose regimen) or 21 days apart in various orders and route of administration combinations (2-dose regimen). The 2-dose regimen induced robust immune responses to provide full protection to animals against parental CO92 and its isogenic F1 deletion mutant (CAF-) challenges during both short- and long-term studies. Mice intranasally (i.n.) immunized with Ad5-YFV first followed by LMA (i.n. or intramuscularly [i.m.]) had higher T- and B-cell proliferative responses and LcrV antibody titers than those in mice vaccinated with LMA (i.n. or i.m.) first ahead of Ad5-YFV (i.n.) during the longon subunit and live-attenuated plague vaccines. We have developed a subunit vaccine, including three components (YscF, F1, and LcrV) using an adenovirus platform (Ad5-YFV). In addition, we have deleted virulence genes of Y. pestis (e.g., lpp, msbB, and ail) to develop a live-attenuated vaccine (LMA). Both of these vaccines generated robust humoral and cellular immunity and were highly efficacious in several animal models. We hypothesized the use of a heterologous prime-boost strategy or administrating both vaccines simultaneously could provide an adjuvant- and/or a needle-free vaccine(s) that has attributes of both vaccines for use in regions of endemicity and during an emergency situation.Rickettsiae are obligate intracellular Gram-negative bacteria transmitted by arthropod vectors. Despite their reduced genomes, the function(s) of the majority of rickettsial proteins remains to be uncovered. APRc is a highly conserved retropepsin-type protease, suggested to act as a modulator of other rickettsial surface proteins with a role in adhesion/invasion. However, APRc’s function(s) in bacterial pathogenesis and virulence remains unknown. This study demonstrates that APRc targets host serum components, combining nonimmune immunoglobulin (Ig)-binding activity with resistance to complement-mediated killing. We confirmed nonimmune human IgG binding in extracts of different rickettsial species and intact bacteria. Our results revealed that the soluble domain of APRc is capable of binding to human (h), mouse, and rabbit IgG and different classes of human Ig (IgG, IgM, and IgA) in a concentration-dependent manner. APRc-hIgG interaction was confirmed with total hIgG and normal human serum. APRc-hIgG displaye far from being resolved. We provide evidence that the highly conserved rickettsial retropepsin-type protease APRc displays nonimmune immunoglobulin (Ig)-binding activity and participates in serum resistance. APRc emerges then as a novel Ig-binding protein from Gram-negative bacteria and the first to be identified in Rickettsia. Bacterial surface proteins capable of Ig binding are known to be multifunctional and key players in immune evasion. We demonstrate that APRc is also a novel moonlighting protein, exhibiting different actions on serum components and acting as a novel evasin. read more This work strengthens APRc as a virulence factor in Rickettsia and its significance as a potential therapeutic target. Our findings significantly contribute to a deeper understanding of the virulence strategies used by intracellular pathogens to subvert host immune responses.β-Lactamase expression is the major mechanism of resistance to penicillins, cephalosporins, and carbapenems in the multidrug-resistant (MDR) bacterium Acinetobacter baumannii. In fact, stable high-level expression of at least one β-lactamase has been rapidly increasing and reported to occur in up to 98.5% of modern A. baumannii isolates recovered in the clinic. Moreover, the OXA-51 β-lactamase is universally present in the A. baumannii chromosome, suggesting it may have a cellular function beyond antibiotic resistance. However, the consequences associated with OXA β-lactamase overexpression on A. baumannii physiology are not well understood. Using peptidoglycan composition analysis, we show that overexpressing the OXA-23 β-lactamase in A. baumannii drives significant collateral changes with alterations consistent with increased amidase activity. Consequently, we predicted that these changes create new cellular vulnerabilities. As proof of principle, a small screen of random transposon insertions revealed three genes, where mutations resulted in a greater than 19-fold loss of viability when OXA-23 was overexpressed.