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1.
Audiol Res ; 13(2): 271-284, 2023 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-37102774

RESUMO

Malawi, as a low-income country in southeastern Africa, severely lacks early identification, diagnosis and intervention measures for hearing loss. Due to its constrained resources, an educational awareness campaign targeted at professionals can be a cost-effective instrument in promoting good health care through awareness, prevention, and early identification of hearing loss. The aim of this study is to assess school teachers' knowledge of hearing health, audiology services, identification, and management of hearing issues before and after an educational intervention. METHODS: A Pre-Survey, followed by an educational intervention, and a Post-Survey were completed by teacher participants. A similar World Health Organization-derived survey was also administered to compare to our locally adapted survey. Trends related to efficacy, performance, and survey improvement were evaluated. RESULTS: A total of 387 teachers participated. The average score on the Post-Survey was significantly improved compared to the Pre-Survey (71% to 97% correct responses) with the educational intervention. The only predictive variable related to performance was the location of the school within the capital of Lilongwe compared to rural sites outside of the capital. Our locally adapted survey compared favorably to the WHO survey. CONCLUSIONS: The results suggest that there is a statistically significant improvement in the implementation of an educational program to increase the knowledge and awareness of hearing health care among teachers. Some topics were more poorly understood than others, suggesting the need for targeted awareness interventions. Location within the capital city had some effect on performance but a high rate of correct responses was achievable across the participants independent of age, teaching experience, or gender. Our data support the idea that hearing health awareness interventions can be an effective and low-cost option to equip teachers to effectively serve as an advocate for improved identification, early diagnosis and appropriate referral of students with hearing loss.

2.
PLoS One ; 18(1): e0279968, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36603014

RESUMO

BACKGROUND: While COVID-19 vaccines reduce adverse outcomes, post-vaccination SARS-CoV-2 infection remains problematic. We sought to identify community factors impacting risk for breakthrough infections (BTI) among fully vaccinated persons by rurality. METHODS: We conducted a retrospective cohort study of US adults sampled between January 1 and December 20, 2021, from the National COVID Cohort Collaborative (N3C). Using Kaplan-Meier and Cox-Proportional Hazards models adjusted for demographic differences and comorbid conditions, we assessed impact of rurality, county vaccine hesitancy, and county vaccination rates on risk of BTI over 180 days following two mRNA COVID-19 vaccinations between January 1 and September 21, 2021. Additionally, Cox Proportional Hazards models assessed the risk of infection among adults without documented vaccinations. We secondarily assessed the odds of hospitalization and adverse COVID-19 events based on vaccination status using multivariable logistic regression during the study period. RESULTS: Our study population included 566,128 vaccinated and 1,724,546 adults without documented vaccination. Among vaccinated persons, rurality was associated with an increased risk of BTI (adjusted hazard ratio [aHR] 1.53, 95% confidence interval [CI] 1.42-1.64, for urban-adjacent rural and 1.65, 1.42-1.91, for nonurban-adjacent rural) compared to urban dwellers. Compared to low vaccine-hesitant counties, higher risks of BTI were associated with medium (1.07, 1.02-1.12) and high (1.33, 1.23-1.43) vaccine-hesitant counties. Compared to counties with high vaccination rates, a higher risk of BTI was associated with dwelling in counties with low vaccination rates (1.34, 1.27-1.43) but not medium vaccination rates (1.00, 0.95-1.07). Community factors were also associated with higher odds of SARS-CoV-2 infection among persons without a documented vaccination. Vaccinated persons with SARS-CoV-2 infection during the study period had significantly lower odds of hospitalization and adverse events across all geographic areas and community exposures. CONCLUSIONS: Our findings suggest that community factors are associated with an increased risk of BTI, particularly in rural areas and counties with high vaccine hesitancy. Communities, such as those in rural and disproportionately vaccine hesitant areas, and certain groups at high risk for adverse breakthrough events, including immunosuppressed/compromised persons, should continue to receive public health focus, targeted interventions, and consistent guidance to help manage community spread as vaccination protection wanes.


Assuntos
COVID-19 , Humanos , Adulto , COVID-19/epidemiologia , COVID-19/prevenção & controle , Vacinas contra COVID-19 , Estudos Retrospectivos , SARS-CoV-2 , Infecções Irruptivas , Vacinação
3.
Front Immunol ; 13: 912038, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36330531

RESUMO

Lymphoid tissues are an important HIV reservoir site that persists in the face of antiretroviral therapy and natural immunity. Targeting these reservoirs by harnessing the antiviral activity of local tissue-resident memory (TRM) CD8+ T-cells is of great interest, but limited data exist on TRM-like cells within lymph nodes of people living with HIV (PLWH). Here, we studied tonsil CD8+ T-cells obtained from PLWH and uninfected controls from South Africa. We show that these cells are preferentially located outside the germinal centers (GCs), the main reservoir site for HIV, and display a low cytolytic and a transcriptionally TRM-like profile distinct from blood CD8+ T-cells. In PLWH, CD8+ TRM-like cells are expanded and adopt a more cytolytic, activated, and exhausted phenotype not reversed by antiretroviral therapy (ART). This phenotype was enhanced in HIV-specific CD8+ T-cells from tonsils compared to matched blood suggesting a higher antigen burden in tonsils. Single-cell transcriptional and clonotype resolution showed that these HIV-specific CD8+ T-cells in the tonsils express heterogeneous signatures of T-cell activation, clonal expansion, and exhaustion ex-vivo. Interestingly, this signature was absent in a natural HIV controller, who expressed lower PD-1 and CXCR5 levels and reduced transcriptional evidence of T-cell activation, exhaustion, and cytolytic activity. These data provide important insights into lymphoid tissue-derived HIV-specific CD8+ TRM-like phenotypes in settings of HIV remission and highlight their potential for immunotherapy and targeting of the HIV reservoirs.


Assuntos
Linfócitos T CD8-Positivos , Infecções por HIV , Humanos , Memória Imunológica , Tonsila Palatina , Receptores CXCR5 , Infecções por HIV/tratamento farmacológico
4.
JAMIA Open ; 5(3): ooac066, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35911666

RESUMO

Objectives: Although the World Health Organization (WHO) Clinical Progression Scale for COVID-19 is useful in prospective clinical trials, it cannot be effectively used with retrospective Electronic Health Record (EHR) datasets. Modifying the existing WHO Clinical Progression Scale, we developed an ordinal severity scale (OS) and assessed its usefulness in the analyses of COVID-19 patient outcomes using retrospective EHR data. Materials and Methods: An OS was developed to assign COVID-19 disease severity using the Observational Medical Outcomes Partnership common data model within the National COVID Cohort Collaborative (N3C) data enclave. We then evaluated usefulness of the developed OS using heterogenous EHR data from January 2020 to October 2021 submitted to N3C by 63 healthcare organizations across the United States. Principal component analysis (PCA) was employed to characterize changes in disease severity among patients during the 28-day period following COVID-19 diagnosis. Results: The data set used in this analysis consists of 2 880 456 patients. PCA of the day-to-day variation in OS levels over the totality of the 28-day period revealed contrasting patterns of variation in disease severity within the first and second 14 days and illustrated the importance of evaluation over the full 28-day period. Discussion: An OS with well-defined, robust features, based on discrete EHR data elements, is useful for assessments of COVID-19 patient outcomes, providing insights on the progression of COVID-19 disease severity over time. Conclusions: The OS provides a framework that can facilitate better understanding of the course of acute COVID-19, informing clinical decision-making and resource allocation.

5.
Artigo em Inglês | MEDLINE | ID: mdl-36712472

RESUMO

Objective: The objective of this study was to determine antibiotic appropriateness based on Loeb minimum criteria (LMC) in patients with and without altered mental status (AMS). Design: Retrospective, quasi-experimental study assessing pooled data from 3 periods pertaining to the implementation of a UTI management guideline. Setting: Academic medical center in Lexington, Kentucky. Patients: Adult patients aged ≥18 years with a collected urinalysis receiving antimicrobial therapy for a UTI indication. Methods: Appropriateness of UTI management was assessed in patients prior to an institutional UTI guideline, after guideline introduction and education, and after implementation of a prospective audit-and-feedback stewardship intervention from September to November 2017-2019. Patient data were pooled and compared between patients noted to have AMS versus those with classic UTI symptoms. Loeb minimum criteria were used to determine whether UTI diagnosis and treatment was warranted. Results: In total, 600 patients were included in the study. AMS was one of the most common indications for testing across the 3 periods (19%-30.5%). Among those with AMS, 25 patients (16.7%) met LMC, significantly less than the 151 points (33.6%) without AMS (P < .001). Conclusions: Patients with AMS are prescribed antibiotic therapy without symptoms indicative of UTI at a higher rate than those without AMS, according to LMC. Further antimicrobial stewardship efforts should focus on prescriber education and development of clearly defined criteria for patients with and without AMS.

6.
JCI Insight ; 6(22)2021 11 22.
Artigo em Inglês | MEDLINE | ID: mdl-34618690

RESUMO

HIV infection in the human gastrointestinal (GI) tract is thought to be central to HIV progression, but knowledge of this interaction is primarily limited to cohorts within Westernized countries. Here, we present a large cohort recruited from high HIV endemic areas in South Africa and found that people living with HIV (PLWH) presented at a younger age for investigation in the GI clinic. We identified severe CD4+ T cell depletion in the GI tract, which was greater in the small intestine than in the large intestine and not correlated with years on antiretroviral treatment (ART) or plasma viremia. HIV-p24 staining showed persistent viral expression, particularly in the colon, despite full suppression of plasma viremia. Quantification of mucosal antiretroviral (ARV) drugs revealed no differences in drug penetration between the duodenum and colon. Plasma markers of gut barrier breakdown and immune activation were elevated irrespective of HIV, but peripheral T cell activation was inversely correlated with loss of gut CD4+ T cells in PLWH alone. T cell activation is a strong predictor of HIV progression and independent of plasma viral load, implying that the irreversible loss of GI CD4+ T cells is a key event in the HIV pathogenesis of PLWH in South Africa, yet the underlying mechanisms remain unknown.


Assuntos
Linfócitos T CD4-Positivos/metabolismo , Infecções por HIV/imunologia , Ativação Linfocitária/imunologia , Doença Crônica , Humanos
7.
Ann Glob Health ; 87(1): 80, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34434716

RESUMO

Background: To meet the rising interest in surgical global health, some surgical residency programs offer global health experiences. The level of interest in these programs, however, and their role in residency recruitment and career planning has not been systematically evaluated. Objective: (1) Define interest in global health among Otolaryngology residents in the USA. (2) Assess engagement of Otolaryngology residencies in global health training. (3) Determine barriers to global health training in residency. Methods: A survey questionnaire was developed and sent to all Otolaryngology Residency Program Directors for distribution to all current Otolaryngology residents in the US. Results: A total of 91 complete surveys were collected. A majority of respondents felt that global health was either "very important" or "extremely important" (67%). Two-thirds of respondents had prior global health experience (68%). While 56% of respondents would definitely participate in a global health elective and 78% would likely or definitely participate, only 37% of residency programs offered a global health experience. The availability of a global health elective significantly correlated with residency match choice in respondents with previous global health experience. The three most common barriers to participation were insufficient time, insufficient funding, and lack of program. Conclusion: Participation in bilateral and equitable international electives is a unique experience of personal and professional growth. There is an interest in these opportunities during residency training among Otolaryngology residents that is not reflected in availability within training programs. This suggests the need for development of humanitarian outreach exposure through global health experiences during surgical residency training.


Assuntos
Saúde Global , Internato e Residência , Otolaringologia/educação , Humanos , Inquéritos e Questionários , Estados Unidos , Voluntários
8.
Mycoses ; 64(9): 1073-1082, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34033158

RESUMO

BACKGROUND: Cryptococcosis is classically associated with the immunocompromised patients but there is a rising appreciation for its impact on the immunocompetent hosts. We sought to analyse the trends, diagnosis, treatment of different hosts and the effect of immunodeficiency and chronic liver disease on relapse and in-house mortality. METHODS: This is a retrospective study of 12 years of patients with cryptococcosis, divided into three different groups: HIV-infected, transplant and non-HIV non-transplant (NHNT). Data were analysed with Chi-square, unpaired parametric t test, simple and multivariate logistic regression analysis. RESULTS: Of 114 identified patients, 23 (20.2%) had HIV infection, 11 (9.6%) had transplant, 80 (70.2%) were NHNT patients. Overall, mortality was 28.1% (32/114) and relapse occurred in 10.5% (12/114) of patients. The mortality trend was higher (OR = 2.346, p = .287) in the transplant group (45.5%, 5/11) than in HIV (26.1%, 6/23) and NHNT groups (26.3%, 21/80). HIV was associated with relapse; 30.4% (7/23) for HIV-positive patients and 5.5% (5/91) for HIV-negative patients (OR = 7.525, p = .002). Chronic liver disease had a large and statistically significant association with mortality on multivariate analysis (OR = 3.583, p = .013) which was more pronounced than the HIV or transplant groups. It was independently associated with mortality by chi-square analysis (OR 3.137, p = .012). CONCLUSION: Chronic liver disease represented 30.7% (35/114) of all studied patients. It was a risk factor for in-hospital mortality. HIV infection and transplant were not statistically significant for mortality. Relapse was highest in the HIV-infected patients at 30.4% (7/23). These data highlight the effect of type and degree of immunocompromise on cryptococcosis.


Assuntos
Criptococose , Doença Hepática Terminal , Infecções por HIV , Criptococose/epidemiologia , Criptococose/mortalidade , Doença Hepática Terminal/epidemiologia , Infecções por HIV/epidemiologia , Humanos , Recidiva , Estudos Retrospectivos , Fatores de Risco , Centros de Atenção Terciária
9.
J Rural Health ; 37(3): 602-623, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33305886

RESUMO

PURPOSE: Appalachian residents have higher cancer prevalence and invasive cancer incidence in almost all cancer types relative to non-Appalachian residents. Public health interventions have been carried out to increase preventive cancer screening participation. However, no studies have evaluated the effectiveness of existing interventions targeting cancer screening uptake in this high-risk population. The main objective of this study is to assess the effectiveness of interventions aimed at increasing uptake and/or continuing participation in screened cancers (breast, cervical, colorectal, lung, and prostate) in Appalachia. METHODS: We conducted a systematic review of electronic databases and gray literature using a combination of MeSH and free-text search terms related to breast, cervical, colorectal, lung, and prostate cancer; mass screening; health promotion; and Appalachia. We identified 3,014 articles of which 15 articles were included. We assessed methodological quality using validated tools and analyzed findings using narrative synthesis. FINDINGS: Fifteen studies reported uptake and/or continued participation in screening interventions; these focused on cervical (n = 7), colorectal (n = 5), breast (n = 2), and lung (n = 1) cancers in Appalachia. Interventions included diverse components: mass media campaigns, community outreach events, community health workers, interpersonal counseling, and educational materials. We found that multi-strategy interventions had higher screening uptake relative to interventions employing 1 intervention strategy. Studies that targeted noncompliant populations and leveraged existing community-based organization partnerships had a substantial increase in screening participation versus others. CONCLUSIONS: There is an urgent need for further research and implementation of effective cancer prevention and screening interventions to reduce disparities in cancer morbidity and mortality in Appalachian populations.


Assuntos
Detecção Precoce de Câncer , Neoplasias , Região dos Apalaches/epidemiologia , Promoção da Saúde , Humanos , Masculino , Programas de Rastreamento , Neoplasias/diagnóstico , Neoplasias/epidemiologia , Neoplasias/prevenção & controle
10.
Viruses ; 12(8)2020 07 31.
Artigo em Inglês | MEDLINE | ID: mdl-32751972

RESUMO

Macrophages are the first line of defence against invading pathogens. They play a crucial role in immunity but also in regeneration and homeostasis. Their remarkable plasticity in their phenotypes and function provides them with the ability to quickly respond to environmental changes and infection. Recent work shows that macrophages undergo cell cycle transition from a G0/terminally differentiated state to a G1 state. This G0-to-G1 transition presents a window of opportunity for HIV-1 infection. Macrophages are an important target for HIV-1 but express high levels of the deoxynucleotide-triphosphate hydrolase SAMHD1, which restricts viral DNA synthesis by decreasing levels of dNTPs. While the G0 state is non-permissive to HIV-1 infection, a G1 state is very permissive to HIV-1 infection. This is because macrophages in a G1 state switch off the antiviral restriction factor SAMHD1 by phosphorylation, thereby allowing productive HIV-1 infection. Here, we explore the macrophage cell cycle and the interplay between its regulation and permissivity to HIV-1 infection.


Assuntos
Ciclo Celular , HIV-1/fisiologia , Macrófagos/fisiologia , Macrófagos/virologia , Animais , Pontos de Checagem do Ciclo Celular , Células Cultivadas , Dano ao DNA , Fase G1 , Bactérias Gram-Negativas/imunologia , Inibidores de Histona Desacetilases/farmacologia , Humanos , Macrófagos/imunologia , Fosforilação , Fase de Repouso do Ciclo Celular , Proteína 1 com Domínio SAM e Domínio HD/metabolismo , Produtos do Gene vif do Vírus da Imunodeficiência Humana/metabolismo , Produtos do Gene vpr do Vírus da Imunodeficiência Humana/metabolismo
12.
Front Immunol ; 10: 1497, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31333650

RESUMO

Children may be the optimal target for HIV vaccine development as they generate substantially more frequent and more potent broadly HIV neutralizing antibodies (bnAbs) than adults. Development of a biomarker that correlates with neutralization breadth in this group could function as a powerful tool to facilitate the development of an HIV vaccine. Previously, we observed that this preferential ability in HIV-infected children over adults to generate bnAbs is associated with an enrichment of circulating follicular helper T-cells (TFH) with an effector phenotype, and the presence of IL-21 secreting HIV-specific TFH within lymphoid tissue germinal centers (GC). In adults, bnAbs development has been linked with high plasma levels of CXCL13, a chemoattractant for CXCR5-expressing TFH cells to the lymph node GC. We sought to test this relationship in HIV-infected children, but found no association between neutralization breadth and plasma levels of CXCL13, or with the Th2 cytokines IL-4 and IL-13, or the TFH associated factor Activin A. However, we did find an unexpected association between plasma IL-5 levels and bnAb development in these children. Importantly, although CXCL13 correlated with total circulating TFH cells, it was not associated with effector TFH. Additionally, raised CXCL13 expression was associated with a lower CD4 percentage, higher viral load and a loss of immune function, implying it is associated with progressive disease rather than HIV-specific GC activity in these subjects. Taken together, our data suggests that IL-5 should be evaluated further as a candidate plasma biomarker for HIV neutralization breadth and for monitoring vaccine responses in the pediatric age group.


Assuntos
Anticorpos Amplamente Neutralizantes/imunologia , Quimiocina CXCL13/sangue , Anticorpos Anti-HIV/imunologia , Infecções por HIV/imunologia , HIV-1/imunologia , Interleucina-5/sangue , Ativinas/sangue , Adolescente , Biomarcadores/sangue , Criança , Estudos de Coortes , Progressão da Doença , Centro Germinativo/imunologia , Infecções por HIV/sangue , Infecções por HIV/virologia , Humanos , Testes de Neutralização , Linfócitos T Auxiliares-Indutores/imunologia , Carga Viral
13.
Elife ; 82019 04 09.
Artigo em Inglês | MEDLINE | ID: mdl-30964004

RESUMO

HIV +Elite and Viremic controllers (EC/VCs) are able to control virus infection, perhaps because of host genetic determinants. We identified 16% (21 of 131) EC/VCs with CD4 +T cells with resistance specific to R5-tropic HIV, reversed after introduction of ccr5. R5 resistance was not observed in macrophages and depended upon the method of T cell activation. CD4 +T cells of these EC/VCs had lower ccr2 and ccr5 RNA levels, reduced CCR2 and CCR5 cell-surface expression, and decreased levels of secreted chemokines. T cells had no changes in chemokine receptor mRNA half-life but instead had lower levels of active transcription of ccr2 and ccr5, despite having more accessible chromatin by ATAC-seq. Other nearby genes were also down-regulated, over a region of ~500 kb on chromosome 3p21. This same R5 resistance phenotype was observed in family members of an index VC, also associated with ccr2/ccr5 down-regulation, suggesting that the phenotype is heritable.


Assuntos
Resistência à Doença , Regulação para Baixo , Família , Infecções por HIV/imunologia , Sobreviventes de Longo Prazo ao HIV , Receptores CCR5/biossíntese , Adulto , Idoso , Linfócitos T CD4-Positivos/química , Linfócitos T CD4-Positivos/virologia , Células Cultivadas , Feminino , HIV-1/crescimento & desenvolvimento , Humanos , Macrófagos/química , Macrófagos/virologia , Masculino , Pessoa de Meia-Idade , Receptores CCR2/biossíntese , Tropismo Viral , Adulto Jovem
14.
Trop Med Infect Dis ; 4(1)2019 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-30626120

RESUMO

Chronic Suppurative Otitis Media (CSOM) is a widely prevalent disease, which is a leading cause of acquired deafness worldwide, and is associated with complications with significant mortality and morbidity. It often responds poorly to standard of care therapy and places a disproportionate burden on at-risk populations. The microbiology and antibiotic resistance of CSOM varies based on local factors, including health care access, comorbidities, and antibiotic prescribing practices. We evaluated the role and feasibility of using routine culture for the treatment of CSOM in rural areas as a means of improving treatment of CSOM. More than 400 patients were screened in a rural clinic in South Africa over six weeks, and 14 met study criteria and consented for participation. Gram-negative organisms predominated overall, although Staphylococcus aureus was the most commonly isolated single species. A majority of the pathogens were relatively sensitive to commonly prescribed antibiotics, but two cases of methicillin resistant Staphylococcus aureus were cultured, and one patient grew a Scedosporium species. Treatment on follow-up was able to be directed by culture results, suggesting routine culture at the initial point of contact with the health care system may play a pivotal role in addressing this widely prevalent and devastating disease.

15.
J Virol ; 87(16): 8962-70, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23740997

RESUMO

The human parainfluenza virus (hPIV) hemagglutinin-neuraminidase (HN) protein binds (H) oligosaccharide receptors that contain N-acetylneuraminic acid (Neu5Ac) and cleaves (N) Neu5Ac from these oligosaccharides. In order to determine if one of HN's two functions is predominant, we measured the affinity of H for its ligands by a solid-phase binding assay with two glycoprotein substrates and by surface plasmon resonance with three monovalent glycans. We compared the dissociation constant (Kd) values from these experiments with previously determined Michaelis-Menten constants (Kms) for the enzyme activity. We found that glycoprotein substrates and monovalent glycans containing Neu5Acα2-3Galß1-4GlcNAc bind HN with Kd values in the 10 to 100 µM range. Km values for HN were previously determined to be on the order of 1 mM (M. M. Tappert, D. F. Smith, and G. M. Air, J. Virol. 85:12146-12159, 2011). A Km value greater than the Kd value indicates that cleavage occurs faster than the dissociation of binding and will dominate under N-permissive conditions. We propose, therefore, that HN is a neuraminidase that can hold its substrate long enough to act as a binding protein. The N activity can therefore regulate binding by reducing virus-receptor interactions when the concentration of receptor is high.


Assuntos
Proteína HN/metabolismo , Vírus da Parainfluenza 1 Humana/enzimologia , Receptores Virais/metabolismo , Humanos , Hidrólise , Cinética , Ligação Proteica , Ressonância de Plasmônio de Superfície
16.
Biophys J ; 104(7): 1595-604, 2013 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-23561536

RESUMO

Many viruses package their genomes concomitant with assembly. Here, we show that this reaction can be described by three coefficients: association of capsid protein (CP) to nucleic acid (NA), KNA; CP-CP interaction, ω; and α, proportional to the work required to package NA. The value of α can vary as NA is packaged. A phase diagram of average lnα versus lnω identifies conditions where assembly is likely to fail or succeed. NA morphology can favor (lnα > 0) or impede (lnα < 0) assembly. As lnω becomes larger, capsids become more stable and assembly becomes more cooperative. Where (lnα + lnω) < 0, the CP is unable to contain the NA, so that assembly results in aberrant particles. This phase diagram is consistent with quantitative studies of cowpea chlorotic mottle virus, hepatitis B virus, and simian virus 40 assembling on ssRNA and dsDNA substrates. Thus, the formalism we develop is suitable for describing and predicting behavior of experimental studies of CP assembly on NA.


Assuntos
DNA Viral/metabolismo , RNA Viral/metabolismo , Vírus/genética , Vírus/metabolismo , Proteínas do Capsídeo/metabolismo , Empacotamento do DNA , DNA Viral/química , DNA Viral/genética , Modelos Moleculares , Conformação Molecular , RNA Viral/química , RNA Viral/genética , Vírion/genética , Vírion/metabolismo
17.
Virology ; 407(2): 281-8, 2010 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-20850162

RESUMO

UV spectra of viruses are complicated by overlapping protein and RNA absorbance and light scattering. We describe and validate methodology for estimating RNA and protein concentration from such spectra. Importantly, we found that encapsidation did not substantially affect RNA absorbance. Combining absorbance data with a known T number, we confirmed that brome mosaic virus packages about 3100 nucleotides/capsid, consistent with its genome. E. coli-expressed hepatitis B virus (HBV) packages host RNA based on capsid charge and volume. We examined HBV capsid protein (Cp183, +15 charge) and a less basic mutant (Cp183-EEE, +12 charge) that mimics a phosphorylated state. Cp183-EEE packaged ~3450 nucleotides per T=4 capsid and Cp183 packaged ~4800 nucleotides, correlating to the size of HBV's RNA pre-genome and mature DNA genome, respectively. The RNA:protein charge ratio (about 1.4 phosphates per positive charge) was consistent with that of other ssRNA viruses. This spectroscopic method is generalizable to any virus-like particle.


Assuntos
Bromovirus/química , DNA Viral/análise , Vírus da Hepatite B/química , RNA Viral/análise , Proteínas Virais/análise , Virologia/métodos , Bromovirus/genética , Bromovirus/metabolismo , Capsídeo/química , Capsídeo/metabolismo , Proteínas do Capsídeo/análise , Vírus da Hepatite B/genética , Vírus da Hepatite B/metabolismo , Microscopia Eletrônica de Transmissão , Espectrofotometria Ultravioleta/instrumentação , Espectrofotometria Ultravioleta/métodos , Montagem de Vírus
18.
J Virol ; 84(14): 7174-84, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20427522

RESUMO

A critical feature of a viral life cycle is the ability to selectively package the viral genome. In vivo, phosphorylated hepatitis B virus (HBV) core protein specifically encapsidates a complex of pregenomic RNA (pgRNA) and viral polymerase; it has been suggested that packaging is specific for the complex. Here, we test the hypothesis that core protein has intrinsic specificity for pgRNA, independent of the polymerase. For these studies, we also evaluated the effect of core protein phosphorylation on assembly and RNA binding, using phosphorylated core protein and a phosphorylation mimic in which S155, S162, and S170 were mutated to glutamic acid. We have developed an in vitro system where capsids are disassembled and assembly-active core protein dimer is purified. With this protein, we have reassembled empty capsids and RNA-filled capsids. We found that core protein dimer bound and encapsidated both the HBV pregenomic RNA and heterologous RNA with high levels of cooperativity, irrespective of phosphorylation. In direct competition assays, no specificity for pregenomic RNA was observed. This suggests that another factor, such as the viral polymerase, is required for specific packaging. These results also beg the question of what prevents HBV core protein from assembling on nonviral RNA, preserving the protein for virus production.


Assuntos
Capsídeo/metabolismo , Vírus da Hepatite B , RNA Viral/metabolismo , RNA/metabolismo , Proteínas do Core Viral/metabolismo , Montagem de Vírus , Genoma Viral , Vírus da Hepatite B/genética , Vírus da Hepatite B/metabolismo , Humanos , Fosforilação , Multimerização Proteica , RNA/genética , RNA Viral/genética , Proteínas do Core Viral/química , Proteínas do Core Viral/genética
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