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1.
PLoS Pathog ; 17(8): e1009800, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34437657

RESUMO

Type I Interferons (IFN-Is) are a family of cytokines which play a major role in inhibiting viral infection. Resultantly, many viruses have evolved mechanisms in which to evade the IFN-I response. Here we tested the impact of expression of 27 different SARS-CoV-2 genes in relation to their effect on IFN production and activity using three independent experimental methods. We identified six gene products; NSP6, ORF6, ORF7b, NSP1, NSP5 and NSP15, which strongly (>10-fold) blocked MAVS-induced (but not TRIF-induced) IFNß production. Expression of the first three of these SARS-CoV-2 genes specifically blocked MAVS-induced IFNß-promoter activity, whereas all six genes induced a collapse in IFNß mRNA levels, corresponding with suppressed IFNß protein secretion. Five of these six genes furthermore suppressed MAVS-induced activation of IFNλs, however with no effect on IFNα or IFNγ production. In sharp contrast, SARS-CoV-2 infected cells remained extremely sensitive to anti-viral activity exerted by added IFN-Is. None of the SARS-CoV-2 genes were able to block IFN-I signaling, as demonstrated by robust activation of Interferon Stimulated Genes (ISGs) by added interferon. This, despite the reduced levels of STAT1 and phospho-STAT1, was likely caused by broad translation inhibition mediated by NSP1. Finally, we found that a truncated ORF7b variant that has arisen from a mutant SARS-CoV-2 strain harboring a 382-nucleotide deletion associating with mild disease (Δ382 strain identified in Singapore & Taiwan in 2020) lost its ability to suppress type I and type III IFN production. In summary, our findings support a multi-gene process in which SARS-CoV-2 blocks IFN-production, with ORF7b as a major player, presumably facilitating evasion of host detection during early infection. However, SARS-CoV-2 fails to suppress IFN-I signaling thus providing an opportunity to exploit IFN-Is as potential therapeutic antiviral drugs.


Assuntos
Interferon beta/metabolismo , SARS-CoV-2/imunologia , Proteínas Virais/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Animais , Chlorocebus aethiops , Fator de Iniciação 2 em Eucariotos/metabolismo , Células HEK293 , Humanos , Interferon beta/genética , Interferon beta/farmacologia , SARS-CoV-2/efeitos dos fármacos , Fator de Transcrição STAT1/metabolismo , Células Vero , Proteínas Virais/genética
2.
Nat Commun ; 12(1): 4270, 2021 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-34257311

RESUMO

The recent dramatic appearance of variants of concern of SARS-coronavirus-2 (SARS-CoV-2) highlights the need for innovative approaches that simultaneously suppress viral replication and circumvent viral escape from host immunity and antiviral therapeutics. Here, we employ genome-wide computational prediction and single-nucleotide resolution screening to reprogram CRISPR-Cas13b against SARS-CoV-2 genomic and subgenomic RNAs. Reprogrammed Cas13b effectors targeting accessible regions of Spike and Nucleocapsid transcripts achieved >98% silencing efficiency in virus-free models. Further, optimized and multiplexed Cas13b CRISPR RNAs (crRNAs) suppress viral replication in mammalian cells infected with replication-competent SARS-CoV-2, including the recently emerging dominant variant of concern B.1.1.7. The comprehensive mutagenesis of guide-target interaction demonstrated that single-nucleotide mismatches does not impair the capacity of a potent single crRNA to simultaneously suppress ancestral and mutated SARS-CoV-2 strains in infected mammalian cells, including the Spike D614G mutant. The specificity, efficiency and rapid deployment properties of reprogrammed Cas13b described here provide a molecular blueprint for antiviral drug development to suppress and prevent a wide range of SARS-CoV-2 mutants, and is readily adaptable to other emerging pathogenic viruses.


Assuntos
Mutação , SARS-CoV-2/fisiologia , Replicação Viral/fisiologia , Animais , Antivirais/farmacologia , COVID-19/tratamento farmacológico , COVID-19/virologia , Sistemas CRISPR-Cas , Chlorocebus aethiops , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Desenvolvimento de Medicamentos , Genoma Viral , Células HEK293 , Humanos , SARS-CoV-2/genética , Glicoproteína da Espícula de Coronavírus/genética , Glicoproteína da Espícula de Coronavírus/metabolismo , Células Vero , Replicação Viral/genética
3.
mSphere ; : e0031321, 2021 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-34133201

RESUMO

The COVID-19 pandemic has impacted and enforced significant restrictions within our societies, including the attendance of public and professional athletes in gyms. Liquid chalk is a commonly used accessory in gyms and is comprised of magnesium carbonate and alcohol that quickly evaporates on the hands to leave a layer of dry chalk. We investigated whether liquid chalk is an antiseptic against highly pathogenic human viruses, including SARS-CoV-2, influenza virus, and noroviruses. Chalk was applied before or after virus, inoculum and recovery of infectious virus was determined to mimic the use in the gym. We observed that addition of chalk before or after virus contact led to a significant reduction in recovery of infectious SARS-CoV-2 and influenza virus but had little impact on norovirus. These observations suggest that the use and application of liquid chalk can be an effective and suitable antiseptic for major sporting events, such as the Olympic Games. IMPORTANCE To restrict the potential transmission and infectivity of SARS-CoV-2, the use of liquid chalk has been a requirement in an active gym setting. However, its effectiveness has not been scientifically proven. Here, we show that the application of liquid chalk before or after virus inoculum significantly impacts recovery of infectious SARS-CoV-2 and influenza viruses but not noroviruses. Thus, our study has shown that the implementation and application of liquid chalk in communal social gym settings is effective in reducing the infectivity of respiratory viruses, and this supports the use of liquid chalk in major sporting events to restrict the impact of COVID-19 on our communities.

4.
Angew Chem Int Ed Engl ; 60(31): 17102-17107, 2021 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-34043272

RESUMO

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in an unprecedented need for diagnostic testing that is critical in controlling the spread of COVID-19. We propose a portable infrared spectrometer with purpose-built transflection accessory for rapid point-of-care detection of COVID-19 markers in saliva. Initially, purified virion particles were characterized with Raman spectroscopy, synchrotron infrared (IR) and AFM-IR. A data set comprising 171 transflection infrared spectra from 29 subjects testing positive for SARS-CoV-2 by RT-qPCR and 28 testing negative, was modeled using Monte Carlo Double Cross Validation with 50 randomized test and model sets. The testing sensitivity was 93 % (27/29) with a specificity of 82 % (23/28) that included positive samples on the limit of detection for RT-qPCR. Herein, we demonstrate a proof-of-concept high throughput infrared COVID-19 test that is rapid, inexpensive, portable and utilizes sample self-collection thus minimizing the risk to healthcare workers and ideally suited to mass screening.


Assuntos
Teste para COVID-19/métodos , COVID-19/diagnóstico , Saliva/química , Animais , Chlorocebus aethiops , Estudos de Coortes , Análise Discriminante , Humanos , Análise dos Mínimos Quadrados , Método de Monte Carlo , Testes Imediatos , Estudo de Prova de Conceito , SARS-CoV-2 , Sensibilidade e Especificidade , Manejo de Espécimes , Espectrofotometria Infravermelho , Células Vero
5.
Cell Rep ; 35(6): 109108, 2021 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-33961822

RESUMO

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) uses subgenomic RNA (sgRNA) to produce viral proteins for replication and immune evasion. We apply long-read RNA and cDNA sequencing to in vitro human and primate infection models to study transcriptional dynamics. Transcription-regulating sequence (TRS)-dependent sgRNA upregulates earlier in infection than TRS-independent sgRNA. An abundant class of TRS-independent sgRNA consisting of a portion of open reading frame 1ab (ORF1ab) containing nsp1 joins to ORF10, and the 3' untranslated region (UTR) upregulates at 48 h post-infection in human cell lines. We identify double-junction sgRNA containing both TRS-dependent and -independent junctions. We find multiple sites at which the SARS-CoV-2 genome is consistently more modified than sgRNA and that sgRNA modifications are stable across transcript clusters, host cells, and time since infection. Our work highlights the dynamic nature of the SARS-CoV-2 transcriptome during its replication cycle.


Assuntos
COVID-19/genética , SARS-CoV-2/genética , Transcrição Genética/genética , Animais , Células CACO-2 , Linhagem Celular , Chlorocebus aethiops , Epigênese Genética , Genoma Viral/genética , Humanos , Evasão da Resposta Imune , Fases de Leitura Aberta , RNA Viral/genética , Transcriptoma , Células Vero , Proteínas Virais/genética
6.
J Virol ; 95(13): e0021921, 2021 06 10.
Artigo em Inglês | MEDLINE | ID: mdl-33853957

RESUMO

No prophylactic vaccine has provided robust protection against human immunodeficiency virus type 1 (HIV-1). Vaccine-induced broadly neutralizing antibodies (bNAbs) have not been achieved in humans and most animals; however, cows vaccinated with HIV-1 envelope trimers produce bNAbs with unusually long third heavy complementarity-determining regions (CDRH3s). Alongside neutralization, Fc-mediated effector functions, including antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis (ADP), may be critical for in vivo bNAb antiviral activity. Here, we aimed to augment the Fc-dependent effector functions of a chimeric human-bovine bNAb, NC-Cow1, which binds the CD4 binding site (CD4bs) and exhibits broader and more potent neutralization than most human CD4bs bNAbs by using an exceptionally long 60-amino acid (aa) CDRH3. The bovine variable region of NC-Cow1 was paired with a human IgG1 Fc region mutated to create the following three variants: G236R/L328R (GRLR) that abrogates Fc-gamma receptor (FcγR) binding, and two variants that enhance binding, namely, G236A/S239D/I332E (GASDIE) and G236A/S239D/A330L/I332E (GASDALIE). Both GASDIE and GASDALIE improved binding to human FcγRIIA and FcγRIIIA, enhanced human natural killer (NK) cell activation, and mediated higher levels of ADCC and ADP activity than the wild-type human IgG1 Fc. GASDALIE mediated higher phagocytic activity than GASDIE. As expected, GRLR eliminated binding to FcγRs and did not mediate ADCC or ADP. We demonstrated that mutations in the human Fc region of bovine chimeric antibodies with ultralong CDRH3s could enhance antibody effector functions while maintaining envelope binding and neutralization. This study will have significant implications in the development of multifunctional anti-HIV antibodies, which may be important to prevent HIV-1 transmission in an antibody-based topical microbicide. IMPORTANCE Despite successful antiviral chemotherapy, human immunodeficiency virus (HIV) is still a lifelong persistent virus, and no vaccine yet prevents HIV transmission. Topical microbicides offer an important alternative method to prevent sexual transmission of HIV-1. With the production of highly potent anti-HIV-1 broadly neutralizing antibodies (bNAbs) and multifunctional antibodies, monoclonal antibodies are now important prophylactic agents. Recently discovered anti-HIV-1 bovine bNAbs (with higher potency and breadth than most human bNAbs) could be novel candidates as potent topical microbicides. Our study is significant as it demonstrates the compatibility of combining bovine-derived neutralization with human-derived antibody-effector functions. This study is a new approach to antibody engineering that strengthens the feasibility of using high-potency bovine variable region bNAbs with augmented Fc function and promotes them as a strong candidate for antibody-mediated therapies.


Assuntos
Citotoxicidade Celular Dependente de Anticorpos/imunologia , Anticorpos Amplamente Neutralizantes/imunologia , Anticorpos Anti-HIV/imunologia , Infecções por HIV/prevenção & controle , Proteínas Recombinantes de Fusão/imunologia , Animais , Bovinos , Linhagem Celular , Infecções por HIV/transmissão , HIV-1/imunologia , Humanos , Imunoglobulina G/imunologia , Células Matadoras Naturais/imunologia , Fagocitose/imunologia , Engenharia de Proteínas , Receptores de IgG/imunologia
7.
Lancet Infect Dis ; 21(10): 1383-1394, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-33887208

RESUMO

BACKGROUND: Given the scale of the ongoing COVID-19 pandemic, the development of vaccines based on different platforms is essential, particularly in light of emerging viral variants, the absence of information on vaccine-induced immune durability, and potential paediatric use. We aimed to assess the safety and immunogenicity of an MF59-adjuvanted subunit vaccine for COVID-19 based on recombinant SARS-CoV-2 spike glycoprotein stabilised in a pre-fusion conformation by a novel molecular clamp (spike glycoprotein-clamp [sclamp]). METHODS: We did a phase 1, double-blind, placebo-controlled, block-randomised trial of the sclamp subunit vaccine in a single clinical trial site in Brisbane, QLD, Australia. Healthy adults (aged ≥18 to ≤55 years) who had tested negative for SARS-CoV-2, reported no close contact with anyone with active or previous SARS-CoV-2 infection, and tested negative for pre-existing SARS-CoV-2 immunity were included. Participants were randomly assigned to one of five treatment groups and received two doses via intramuscular injection 28 days apart of either placebo, sclamp vaccine at 5 µg, 15 µg, or 45 µg, or one dose of sclamp vaccine at 45 µg followed by placebo. Participants and study personnel, except the dose administration personnel, were masked to treatment. The primary safety endpoints included solicited local and systemic adverse events in the 7 days after each dose and unsolicited adverse events up to 12 months after dosing. Here, data are reported up until day 57. Primary immunogenicity endpoints were antigen-specific IgG ELISA and SARS-CoV-2 microneutralisation assays assessed at 28 days after each dose. The study is ongoing and registered with ClinicalTrials.gov, NCT04495933. FINDINGS: Between June 23, 2020, and Aug 17, 2020, of 314 healthy volunteers screened, 120 were randomly assigned (n=24 per group), and 114 (95%) completed the study up to day 57 (mean age 32·5 years [SD 10·4], 65 [54%] male, 55 [46%] female). Severe solicited reactions were infrequent and occurred at similar rates in participants receiving placebo (two [8%] of 24) and the SARS-CoV-2 sclamp vaccine at any dose (three [3%] of 96). Both solicited reactions and unsolicited adverse events occurred at a similar frequency in participants receiving placebo and the SARS-CoV-2 sclamp vaccine. Solicited reactions occurred in 19 (79%) of 24 participants receiving placebo and 86 (90%) of 96 receiving the SARS-CoV-2 sclamp vaccine at any dose. Unsolicited adverse events occurred in seven (29%) of 24 participants receiving placebo and 35 (36%) of 96 participants receiving the SARS-CoV-2 sclamp vaccine at any dose. Vaccination with SARS-CoV-2 sclamp elicited a similar antigen-specific response irrespective of dose: 4 weeks after the initial dose (day 29) with 5 µg dose (geometric mean titre [GMT] 6400, 95% CI 3683-11 122), with 15 µg dose (7492, 4959-11 319), and the two 45 µg dose cohorts (8770, 5526-13 920 in the two-dose 45 µg cohort; 8793, 5570-13 881 in the single-dose 45 µg cohort); 4 weeks after the second dose (day 57) with two 5 µg doses (102 400, 64 857-161 676), with two 15 µg doses (74 725, 51 300-108 847), with two 45 µg doses (79 586, 55 430-114 268), only a single 45 µg dose (4795, 2858-8043). At day 57, 67 (99%) of 68 participants who received two doses of sclamp vaccine at any concentration produced a neutralising immune response, compared with six (25%) of 24 who received a single 45 µg dose and none of 22 who received placebo. Participants receiving two doses of sclamp vaccine elicited similar neutralisation titres, irrespective of dose: two 5 µg doses (GMT 228, 95% CI 146-356), two 15 µg doses (230, 170-312), and two 45 µg doses (239, 187-307). INTERPRETATION: This first-in-human trial shows that a subunit vaccine comprising mammalian cell culture-derived, MF59-adjuvanted, molecular clamp-stabilised recombinant spike protein elicits strong immune responses with a promising safety profile. However, the glycoprotein 41 peptide present in the clamp created HIV diagnostic assay interference, a possible barrier to widespread use highlighting the criticality of potential non-spike directed immunogenicity during vaccine development. Studies are ongoing with alternative molecular clamp trimerisation domains to ameliorate this response. FUNDING: Coalition for Epidemic Preparedness Innovations, National Health and Medical Research Council, Queensland Government, and further philanthropic sources listed in the acknowledgments.


Assuntos
Adjuvantes Imunológicos/farmacologia , Vacinas contra COVID-19/administração & dosagem , COVID-19/prevenção & controle , Glicoproteína da Espícula de Coronavírus/imunologia , Esqualeno/imunologia , Adulto , Anticorpos Neutralizantes/sangue , Anticorpos Antivirais/sangue , Austrália , Feminino , Voluntários Saudáveis , Humanos , Masculino , Pandemias/prevenção & controle , Polissorbatos , Vacinação/efeitos adversos , Adulto Jovem
8.
Vaccines (Basel) ; 9(3)2021 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-33801906

RESUMO

An optimal prophylactic vaccine to prevent human immunodeficiency virus (HIV-1) transmission should elicit protective antibody responses against the HIV-1 envelope glycoprotein (Env). Replication-incompetent HIV-1 virus-like particles (VLPs) offer the opportunity to present virion-associated Env with a native-like structure during vaccination that closely resembles that encountered on infectious virus. Here, we optimized the incorporation of Env into previously designed mature-form VLPs (mVLPs) and assessed their immunogenicity in mice. The incorporation of Env into mVLPs was increased by replacing the Env transmembrane and cytoplasmic tail domains with those of influenza haemagglutinin (HA-TMCT). Furthermore, Env was stabilized on the VLP surface by introducing an interchain disulfide and proline substitution (SOSIP) mutations typically employed to stabilize soluble Env trimers. The resulting mVLPs efficiently presented neutralizing antibody epitopes while minimizing exposure of non-neutralizing antibody sites. Vaccination of mice with mVLPs elicited a broader range of Env-specific antibody isotypes than Env presented on immature VLPs or extracellular vesicles. The mVLPs bearing HA-TMCT-modified Env consistently induced anti-Env antibody responses that mediated modest neutralization activity. These mVLPs are potentially useful immunogens for eliciting neutralizing antibody responses that target native Env epitopes on infectious HIV-1 virions.

9.
Proc Natl Acad Sci U S A ; 118(19)2021 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-33893175

RESUMO

Neutralizing antibodies are important for immunity against SARS-CoV-2 and as therapeutics for the prevention and treatment of COVID-19. Here, we identified high-affinity nanobodies from alpacas immunized with coronavirus spike and receptor-binding domains (RBD) that disrupted RBD engagement with the human receptor angiotensin-converting enzyme 2 (ACE2) and potently neutralized SARS-CoV-2. Epitope mapping, X-ray crystallography, and cryo-electron microscopy revealed two distinct antigenic sites and showed two neutralizing nanobodies from different epitope classes bound simultaneously to the spike trimer. Nanobody-Fc fusions of the four most potent nanobodies blocked ACE2 engagement with RBD variants present in human populations and potently neutralized both wild-type SARS-CoV-2 and the N501Y D614G variant at concentrations as low as 0.1 nM. Prophylactic administration of either single nanobody-Fc or as mixtures reduced viral loads by up to 104-fold in mice infected with the N501Y D614G SARS-CoV-2 virus. These results suggest a role for nanobody-Fc fusions as prophylactic agents against SARS-CoV-2.


Assuntos
Anticorpos Neutralizantes , Anticorpos Antivirais , COVID-19 , SARS-CoV-2/imunologia , Anticorpos de Domínio Único , Enzima de Conversão de Angiotensina 2/imunologia , Animais , Anticorpos Neutralizantes/imunologia , Anticorpos Neutralizantes/farmacologia , Anticorpos Antivirais/imunologia , Anticorpos Antivirais/farmacologia , COVID-19/tratamento farmacológico , COVID-19/imunologia , Camelídeos Americanos , Humanos , Camundongos , Anticorpos de Domínio Único/imunologia , Anticorpos de Domínio Único/farmacologia
10.
Lancet Infect Dis ; 21(1): e2-e10, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32986997

RESUMO

Human T-cell lymphotropic virus type-1 (HTLV-1) has a large global burden and in some key communities, such as Indigenous Australians living in remote areas, greater than 45% of people are infected. Despite HTLV-1 causing serious malignancy and myelopathic paraparesis, and a significant association with a range of inflammatory comorbidities and secondary infections that shorten lifespan, few biomedical interventions are available. HTLV-1 starkly contrasts with other blood-borne sexually transmitted viral infections, such as, HIV, hepatitis B virus, and hepatitis C virus, with no antiviral treatments that reduce virus-infected cells, no rapid diagnostics or biomarker assays suitable for use in remote settings, and no effective vaccine. We review how the replication strategies and molecular properties of HTLV-1 establish a long-term stealthy viral pathogenesis through a fine-tuned balance of persistence, immune cell dysfunction, and proliferation of proviral infected cells that collectively present robust barriers to treatment and prevention. An understanding of the nature of the HTLV-1 provirus and opposing actions of viral-coded negative-sense HBZ and positive-sense regulatory proteins Tax, p12 and its cleaved product p8, and p30, is needed to improve the biomedical tools for preventing transmission and improving the long-term health of people with this lifelong infection.


Assuntos
Regulação Viral da Expressão Gênica , Infecções por HTLV-I/epidemiologia , Infecções por HTLV-I/patologia , Interações Hospedeiro-Patógeno , Vírus Linfotrópico T Tipo 1 Humano/genética , Vírus Linfotrópico T Tipo 1 Humano/patogenicidade , Linfócitos T/patologia , Austrália/epidemiologia , Humanos , Recidiva
11.
Viruses ; 12(6)2020 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-32517260

RESUMO

The Australasian Virology Society (AVS) aims to promote, support and advocate for the discipline of virology in the Australasian region. The society was incorporated in 2011 after 10 years operating as the Australian Virology Group (AVG) founded in 2001, coinciding with the inaugural biennial scientific meeting. AVS conferences aim to provide a forum for the dissemination of all aspects of virology, foster collaboration, and encourage participation by students and post-doctoral researchers. The tenth Australasian Virology Society (AVS10) scientific meeting was held on 2-5 December 2019 in Queenstown, New Zealand. This report highlights the latest research presented at the meeting, which included cutting-edge virology presented by our international plenary speakers Ana Fernandez-Sesma and Benjamin tenOever, and keynote Richard Kuhn. AVS10 honoured female pioneers in Australian virology, Lorena Brown and Barbara Coulson. We report outcomes from the AVS10 career development session on "Successfully transitioning from post-doc to lab head", winners of best presentation awards, and the AVS gender equity policy, initiated in 2013. Plans for the 2021 meeting are underway which will celebrate the 20th anniversary of AVS where it all began, in Fraser Island, Queensland, Australia.


Assuntos
Virologia/organização & administração , Austrália , Distinções e Prêmios , Processos Grupais , Sociedades Científicas
12.
Retrovirology ; 17(1): 11, 2020 05 12.
Artigo em Inglês | MEDLINE | ID: mdl-32398094

RESUMO

Human T cell leukemia virus type-1 (HTLV-1) was the first retrovirus found to cause cancer in humans, but the mechanisms that drive the development of leukemia and other diseases associated with HTLV-1 infection remain to be fully understood. This review describes the functional properties of p13, an 87-amino acid protein coded by HTLV-1 open reading frame II (orf-II). p13 is mainly localized in the inner membrane of the mitochondria, where it induces potassium (K+) influx and reactive oxygen species (ROS) production, which can trigger either proliferation or apoptosis, depending on the ROS setpoint of the cell. Recent evidence indicates that p13 may influence the cell's innate immune response to viral infection and the infected cell phenotype. Association of the HTLV-1 transcriptional activator, Tax, with p13 increases p13's stability, leads to its partial co-localization with Tax in nuclear speckles, and reduces the ability of Tax to interact with the transcription cofactor CBP/p300. Comparison of p13 sequences isolated from HTLV-1-infected individuals revealed a small number of amino acid variations in the domains controlling the subcellular localization of the protein. Disruptive mutations of p13 were found in samples obtained from asymptomatic patients with low proviral load. p13 sequences of HTLV-1 subtype C isolates from indigenous Australian patients showed a high degree of identity among each other, with all samples containing a pattern of 5 amino acids that distinguished them from other subtypes. Further characterization of p13's functional properties and sequence variants may lead to a deeper understanding of the impact of p13 as a contributor to the clinical manifestations of HTLV-1 infection.


Assuntos
Variação Genética , Vírus Linfotrópico T Tipo 1 Humano/genética , Proteínas dos Retroviridae/genética , Animais , Humanos , Fases de Leitura Aberta
13.
Nucleic Acids Res ; 48(5): 2643-2660, 2020 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-31875221

RESUMO

Tat protein is essential to fully activate HIV transcription and processing of viral mRNA, and therefore determines virus expression in productive replication and the establishment and maintenance of latent infection. Here, we used thermodynamic and structure analyses to define a highly conserved sequence-structure in tat mRNA that functions as Tat IRES modulator of tat mRNA (TIM-TAM). By impeding cap-dependent ribosome progression during authentic spliced tat mRNA translation, TIM-TAM stable structure impacts on timing and level of Tat protein hence controlling HIV production and infectivity along with promoting latency. TIM-TAM also adopts a conformation that mediates Tat internal ribosome entry site (IRES)-dependent translation during the early phases of infection before provirus integration. Our results document the critical role of TIM-TAM in Tat expression to facilitate virus reactivation from latency, with implications for HIV treatment and drug development.


Assuntos
Sequência Conservada , Infecções por HIV/virologia , HIV-1/genética , Sítios Internos de Entrada Ribossomal/genética , RNA Viral/química , RNA Viral/genética , Latência Viral/genética , Produtos do Gene tat do Vírus da Imunodeficiência Humana/metabolismo , Sequência de Bases , Sequência Conservada/genética , Células HeLa , Humanos , Modelos Biológicos , Conformação de Ácido Nucleico , Biossíntese de Proteínas , Provírus/genética , RNA Mensageiro/metabolismo , Ativação Viral
14.
Retrovirology ; 16(1): 42, 2019 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-31852501

RESUMO

The extraordinarily high prevalence of HTLV-1 subtype C (HTLV-1C) in some isolated indigenous communities in Oceania and the severity of the health conditions associated with the virus impress the great need for basic and translational research to prevent and treat HTLV-1 infection. The genome of the virus's most common subtype, HTLV-1A, encodes structural, enzymatic, and regulatory proteins that contribute to viral persistence and pathogenesis. Among these is the p30 protein encoded by the doubly spliced Tax-orf II mRNA, a nuclear/nucleolar protein with both transcriptional and post-transcriptional activity. The p30 protein inhibits the productive replication cycle via nuclear retention of the mRNA that encodes for both the viral transcriptional trans-activator Tax, and the Rex proteins that regulate the transport of incompletely spliced viral mRNA to the cytoplasm. In myeloid cells, p30 inhibits the PU-1 transcription factor that regulates interferon expression and is a critical mediator of innate and adaptive immunity. Furthermore, p30 alters gene expression, cell cycle progression, and DNA damage responses in T-cells, raising the hypothesis that p30 may directly contribute to T cell transformation. By fine-tuning viral expression while also inhibiting host innate responses, p30 is likely essential for viral infection and persistence. This concept is supported by the finding that macaques, a natural host for the closely genetically related simian T-cell leukemia virus 1 (STLV-1), exposed to an HTLV-1 knockout for p30 expression by a single point mutation do not became infected unless reversion and selection of the wild type HTLV-1 genotype occurs. All together, these data suggest that inhibition of p30 may help to curb and eventually eradicate viral infection by exposing infected cells to an effective host immune response.


Assuntos
Regulação Viral da Expressão Gênica , Vírus Linfotrópico T Tipo 1 Humano/fisiologia , Proteínas dos Retroviridae/genética , Latência Viral/genética , Animais , Linhagem Celular , Expressão Gênica , Genótipo , Infecções por HTLV-I/imunologia , Infecções por HTLV-I/virologia , Vírus Linfotrópico T Tipo 1 Humano/genética , Vírus Linfotrópico T Tipo 1 Humano/imunologia , Humanos , Macaca/virologia , RNA Viral/genética , Proteínas dos Retroviridae/imunologia
15.
Retrovirology ; 16(1): 43, 2019 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-31852543

RESUMO

The human T cell leukemia virus type 1 (HTVL-1), first reported in 1980 by Robert Gallo's group, is the etiologic agent of both cancer and inflammatory diseases. Despite approximately 40 years of investigation, the prognosis for afflicted patients remains poor with no effective treatments. The virus persists in the infected host by evading the host immune response and inducing proliferation of infected CD4+ T-cells. Here, we will review the role that viral orf-I protein products play in altering intracellular signaling, protein expression and cell-cell communication in order to escape immune recognition and promote T-cell proliferation. We will also review studies of orf-I mutations found in infected patients and their potential impact on viral load, transmission and persistence. Finally, we will compare the orf-I gene in HTLV-1 subtypes as well as related STLV-1.


Assuntos
Infecções por HTLV-I/transmissão , Infecções por HTLV-I/virologia , Vírus Linfotrópico T Tipo 1 Humano/genética , Proteínas Virais Reguladoras e Acessórias/genética , Linfócitos T CD4-Positivos/virologia , Proliferação de Células , Infecções por HTLV-I/imunologia , Vírus Linfotrópico T Tipo 1 Humano/imunologia , Vírus Linfotrópico T Tipo 1 Humano/patogenicidade , Humanos , Evasão da Resposta Imune , Paraparesia Espástica Tropical/imunologia , Vírus Linfotrópico T Tipo 1 de Símios/genética , Carga Viral , Proteínas Virais Reguladoras e Acessórias/imunologia
16.
PLoS One ; 14(8): e0220986, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31430333

RESUMO

A promising strategy for the enhancement of vaccine-mediated immune responses is by directly targeting protein antigens to immune cells. Targeting of antigens to the dendritic cell (DC) molecule Clec9A has been shown to enhance antibody affinity and titers for model antigens, and influenza and enterovirus antigens, and may be advantageous for immunogens that otherwise fail to elicit antibodies with sufficient titers and breadth for broad protection, such as the envelope protein (Env) of HIV. Previously employed targeting strategies often utilize receptor-specific antibodies, however it is impractical to conjugate a bivalent IgG antibody to oligomeric antigens, including HIV Env trimers. Here we designed single chain variable fragment (scFv) and single chain Fab (scFab) constructs of a Clec9A-targeting antibody, expressed as genetically fused conjugates with the soluble ectodomain of Env, gp140. This conjugation did not affect the presentation of Env neutralising antibody epitopes. The scFab moiety was shown to be more stable than scFv, and in the context of gp140 fusions, was able to mediate better binding to recombinant and cell surface-expressed Clec9A, although the level of binding to cell-surface Clec9A was lower than that of the anti-Clec9A IgG. However, binding to Clec9A on the surface of DCs was not detected. Mouse immunization experiments suggested that the Clec9A-binding activity of the scFab-gp140 conjugate was insufficient to enhance Env-specific antibody responses. This is an important first proof of principle study demonstrating the conjugation of a scFab to an oligomeric protein antigen, and that an scFab displays better antigen binding than the corresponding scFv. Future developments of this technique that increase the scFab affinity will provide a valuable means to target oligomeric proteins to cell surface antigens of interest, improving vaccine-generated immune responses.


Assuntos
Vacinas contra a AIDS/imunologia , Infecções por HIV/terapia , Proteínas Recombinantes de Fusão/imunologia , Anticorpos de Cadeia Única/imunologia , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologia , Vacinas contra a AIDS/administração & dosagem , Vacinas contra a AIDS/genética , Animais , Anticorpos Neutralizantes/imunologia , Afinidade de Anticorpos , Antígenos Virais/genética , Antígenos Virais/imunologia , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Epitopos/imunologia , Feminino , Células HEK293 , Anticorpos Anti-HIV/imunologia , Infecções por HIV/imunologia , Infecções por HIV/virologia , Humanos , Imunogenicidade da Vacina , Lectinas Tipo C/imunologia , Lectinas Tipo C/metabolismo , Camundongos , Estudo de Prova de Conceito , Domínios Proteicos/genética , Domínios Proteicos/imunologia , Receptores Mitogênicos/imunologia , Receptores Mitogênicos/metabolismo , Proteínas Recombinantes de Fusão/administração & dosagem , Proteínas Recombinantes de Fusão/genética , Anticorpos de Cadeia Única/administração & dosagem , Anticorpos de Cadeia Única/genética , Vacinação/métodos , Vacinas de DNA/administração & dosagem , Vacinas de DNA/genética , Vacinas de DNA/imunologia , Produtos do Gene env do Vírus da Imunodeficiência Humana/administração & dosagem , Produtos do Gene env do Vírus da Imunodeficiência Humana/genética
17.
Viruses ; 11(6)2019 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-31159488

RESUMO

A prophylactic vaccine eliciting both broad neutralizing antibodies (bNAbs) to the HIV-1 envelope glycoprotein (Env) and strong T cell responses would be optimal for preventing HIV-1 transmissions. Replication incompetent HIV-1 virus-like particles (VLPs) offer the opportunity to present authentic-structured, virion-associated Env to elicit bNAbs, and also stimulate T cell responses. Here, we optimize our DNA vaccine plasmids as VLP expression vectors for efficient Env incorporation and budding. The original vector that was used in human trials inefficiently produced VLPs, but maximized safety by inactivating RNA genome packaging, enzyme functions that are required for integration into the host genome, and deleting accessory proteins Vif, Vpr, and Nef. These original DNA vaccine vectors generated VLPs with incomplete protease-mediated cleavage of Gag and were irregularly sized. Mutations to restore function within the defective genes revealed that several of the reverse transcriptase (RT) deletions mediated this immature phenotype. Here, we made efficient budding, protease-processed, and mature-form VLPs that resembled infectious virions by introducing alternative mutations that completely removed the RT domain, but preserved most other safety mutations. These VLPs, either expressed from DNA vectors in vivo or purified after expression in vitro, are potentially useful immunogens that can be used to elicit antibody responses that target Env on fully infectious HIV-1 virions.


Assuntos
HIV-1/imunologia , Vacinas de DNA , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologia , Vacinas contra a AIDS/biossíntese , Vacinas contra a AIDS/imunologia , Animais , Vetores Genéticos , Infecções por HIV/prevenção & controle , HIV-1/genética , Humanos , Imunogenicidade da Vacina , Linfócitos T/imunologia , Linfócitos T/virologia , Vacinas de DNA/biossíntese , Vacinas de DNA/imunologia , Vírion/genética , Vírion/imunologia , Produtos do Gene env do Vírus da Imunodeficiência Humana/biossíntese , Produtos do Gene env do Vírus da Imunodeficiência Humana/genética
18.
J Vis Exp ; (143)2019 01 22.
Artigo em Inglês | MEDLINE | ID: mdl-30735158

RESUMO

HIV remains incurable due to the existence of a reservoir of cells that harbors stable and latent form of the virus, which stays invisible to the immune system and is not targeted by the current antiretroviral therapy (cART). Transcription and splicing have been shown to reinforce HIV-1 latency in resting CD4+ T cells. Reversal of latency by the use of latency reversal agents (LRAs) in the "shock and kill" approach has been studied extensively in an attempt to purge this reservoir but has thus far not shown any success in clinical trials due to the lack of development of adequate small molecules that can efficiently perturb this reservoir. The protocol presented here provides a method for reliably and efficiently assessing latency reversal agents (LRAs) on HIV transcription and splicing. This approach is based on the use of an LTR-driven dual color reporter that can simultaneously measure the effect of an LRA on transcription and splicing by flow cytometry. The protocol described here is adequate for adherent cells as well as the cells in suspension. It is useful for testing a large number of drugs in a high throughput system. The method is technically simple to implement and cost-effective. In addition, the use of flow cytometry allows the assessment of cell viability and thus drug toxicity at the same time.


Assuntos
Infecções por HIV/virologia , Splicing de RNA/fisiologia , Latência Viral/fisiologia , Humanos
19.
AIDS ; 33(2): 199-209, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-30562171

RESUMO

OBJECTIVE: To determine whether latency can be established and reversed in both proliferating and nonproliferating CD4+ T cells in the same model in vitro. METHODS: Activated CD4+ T cells were infected with either a nonreplication competent, luciferase reporter virus or wild-type full-length enhanced green fluorescent protein (EGFP) reporter virus and cultured for 12 days. The cells were then sorted by flow cytometry to obtain two distinct T-cell populations that did not express the T-cell activation markers, CD69, CD25 and human leukocyte antigen (HLA)-DR: CD69CD25HLA-DR small cells (nonblasts) that had not proliferated in vitro following mitogen stimulation and CD69CD25HLA-DR large cells (which we here call transitional blasts) that had proliferated. The cells were then reactivated with latency-reversing agents and either luciferase or EGFP quantified. RESULTS: Inducible luciferase expression, consistent with latent infection, was observed in nonblasts and transitional blasts following stimulation with either phorbol-myristate-acetate/phytohemagglutinin (3.8 ±â€Š1 and 2.9 ±â€Š0.5 fold above dimethyl sulfoxide, respectively) or romidepsin (2.1 ±â€Š0.6 and 1.8 ±â€Š0.2 fold above dimethyl sulfoxide, respectively). Constitutive expression of luciferase was higher in transitional blasts compared with nonblasts. Using wild-type full-length EGFP reporter virus, inducible virus was observed in nonblasts but not in transitional blasts. No significant difference was observed in the response to latency-reversing agents in either nonblasts or transitional blasts. CONCLUSION: HIV latency can be established in vitro in resting T cells that have not proliferated (nonblasts) and blasts that have proliferated (transitional blasts). This model could potentially be used to assess new strategies to eliminate latency.


Assuntos
Linfócitos T CD4-Positivos/fisiologia , Linfócitos T CD4-Positivos/virologia , Proliferação de Células , HIV/fisiologia , Latência Viral , Antígenos CD/análise , Antígenos de Diferenciação de Linfócitos T/análise , Linfócitos T CD4-Positivos/química , Linfócitos T CD4-Positivos/classificação , Células Cultivadas , Citometria de Fluxo , Antígenos HLA-DR/análise , Humanos , Subunidade alfa de Receptor de Interleucina-2/análise , Lectinas Tipo C/análise , Coloração e Rotulagem
20.
Adv Exp Med Biol ; 1075: 187-212, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30030794

RESUMO

HIV remains incurable due to the existence of a reservoir of cells that harbor intact integrated genomes of the virus in the absence of viral replication. This population of infected cells remains invisible to the immune system and is not targeted by the drugs used in the current antiretroviral therapies (cART). Reversal of latency by the use of inhibitors of chromatin-remodeling enzymes has been studied extensively in an attempt to purge this reservoir of latent HIV but has thus far not shown any success in clinical trials. The full complexity of latent HIV infection has still not been appreciated, and the gaps in knowledge prevent development of adequate small-molecule compounds that can effectively perturb this reservoir. In this review, we will examine the role of epigenetic silencing of HIV transcription, posttranscriptional regulation, and mRNA processing in promoting HIV-1 latency.


Assuntos
HIV-1/fisiologia , Latência Viral , Fármacos Anti-HIV/farmacologia , Fármacos Anti-HIV/uso terapêutico , Núcleo Celular/ultraestrutura , Cromatina/química , Cromatina/genética , Epigênese Genética , Regulação Viral da Expressão Gênica , Inativação Gênica , Infecções por HIV/tratamento farmacológico , Infecções por HIV/virologia , HIV-1/efeitos dos fármacos , HIV-1/genética , Humanos , Regiões Promotoras Genéticas , RNA Polimerase II/metabolismo , Processamento Pós-Transcricional do RNA , RNA Mensageiro/genética , RNA não Traduzido/genética , RNA Viral/genética , Fatores de Transcrição/metabolismo , Transcrição Genética , Integração Viral , Latência Viral/efeitos dos fármacos , Latência Viral/fisiologia , Replicação Viral
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