RESUMO
BACKGROUND: The extent to which influenza recurrence depends upon waning immunity from prior infection is undefined. We used antibody titers of Ha-Nam cohort participants to estimate protection curves and decay trajectories. METHODS: Households (270) participated in influenza-like-illness (ILI) surveillance and provided blood at intervals spanning laboratory-confirmed virus transmission. Sera were tested in hemagglutination inhibition assay. Infection was defined as influenza virus-positive ILI and/or seroconversion. Median protective titers were estimated using scaled-logistic regression to model pretransmission titer against infection status in that season, limiting analysis to households with infection(s). Titers were modelled against month since infection using mixed-effects linear regression to estimate decay and when titers fell below protection thresholds. RESULTS: From December 2008-2012, 295 and 314 participants were infected with H1N1pdm09-like and A/Perth/16/09-like (H3N2Pe09) viruses, respectively. The proportion protected rose more steeply with titer for H1N1pdm09 than for H3N2Pe09, and estimated 50% protection titers were 19.6 and 37.3, respectively. Postinfection titers started higher against H3N2Pe09 but decayed more steeply than against H1N1pdm09. Seroprotection was estimated to be sustained against H1N1pdm09 but to wane by 8-months for H3N2Pe09. CONCLUSIONS: Estimates indicate that infection induces durable seroprotection against H1N1pdm09 but not H3N2Pe09, which could in part account for the younger age of A(H1N1) versus A(H3N2) cases.
Assuntos
Vírus da Influenza A Subtipo H1N1 , Vacinas contra Influenza , Influenza Humana , Humanos , Influenza Humana/epidemiologia , Anticorpos Antivirais , Vírus da Influenza A Subtipo H3N2 , Testes de Inibição da HemaglutinaçãoRESUMO
A cluster of severe acute respiratory syndrome coronavirus 2 infections in Danang, Vietnam, began July 25, 2020, and resulted in 551 confirmed cases and 35 deaths as of February 2021. We analyzed 26 sequences from this cluster and identified a novel shared mutation in nonstructural protein 9, suggesting a single introduction into Vietnam.
Assuntos
COVID-19 , SARS-CoV-2 , Humanos , Mutação , Proteínas de Ligação a RNA , Vietnã/epidemiologia , Proteínas ViraisRESUMO
Mutation and reassortment of highly pathogenic avian influenza A(H5N1) viruses at the animal-human interface remain a major concern for emergence of viruses with pandemic potential. To understand the relationship of H5N1 viruses circulating in poultry and those isolated from humans, comprehensive phylogenetic and molecular analyses of viruses collected from both hosts in Vietnam between 2003 and 2010 were performed. We examined the temporal and spatial distribution of human cases relative to H5N1 poultry outbreaks and characterized the genetic lineages and amino acid substitutions in each gene segment identified in humans relative to closely related viruses from avian hosts. Six hemagglutinin clades and 8 genotypes were identified in humans, all of which were initially identified in poultry. Several amino acid mutations throughout the genomes of viruses isolated from humans were identified, indicating the potential for poultry viruses infecting humans to rapidly acquire molecular markers associated with mammalian adaptation and antiviral resistance.
Assuntos
Virus da Influenza A Subtipo H5N1/isolamento & purificação , Influenza Aviária/epidemiologia , Influenza Humana/epidemiologia , Sequência de Aminoácidos , Animais , Farmacorresistência Viral Múltipla , Genótipo , Técnicas de Genotipagem , Humanos , Virus da Influenza A Subtipo H5N1/genética , Influenza Aviária/tratamento farmacológico , Influenza Aviária/transmissão , Influenza Humana/tratamento farmacológico , Pandemias , Filogenia , Aves Domésticas/virologia , RNA Viral/genética , Análise de Sequência de RNA , Análise Espaço-Temporal , Vietnã/epidemiologia , Proteínas Virais/genéticaRESUMO
Rural farming communities in northern Vietnam do not routinely practice vaccination for influenza A viruses (IAV) for either humans or poultry, which enables us to study transmission intensity via seroepidemiology. Using samples from a longitudinal cohort of farming households, we determined the number of symptomatic and asymptomatic human infections for seasonal IAV and avian A/H9 over 2 years. As expected, we detected virologically confirmed acute cases of seasonal IAV in humans, as well as large numbers of subclinical seroconversions to A/H1pdm [55/265 (21â%)], A/H3 [95/265 (36â%)] and A/H9 [24/265 (9â%)]. Five of the A/H9 human seroconverters likely represented true infections rather than heterosubtypic immunity, because the individuals seroconverted solely to A/H9. Among co-located poultry, we found significantly higher seroprevalance for A/H5 compared to A/H9 in both chickens and ducks [for northern study sites overall, 337/1105 (30.5â%) seropositive for A/H5 and 123/1105 (11.1â%) seropositive for A/H9].
Assuntos
Vírus da Influenza A Subtipo H9N2/isolamento & purificação , Influenza Aviária/virologia , Influenza Humana/virologia , Doenças das Aves Domésticas/virologia , Adolescente , Adulto , Idoso , Agricultura , Animais , Anticorpos Antivirais/sangue , Galinhas , Criança , Pré-Escolar , Patos , Feminino , Humanos , Lactente , Vírus da Influenza A Subtipo H9N2/classificação , Vírus da Influenza A Subtipo H9N2/genética , Vírus da Influenza A Subtipo H9N2/imunologia , Influenza Aviária/sangue , Influenza Aviária/epidemiologia , Influenza Aviária/transmissão , Influenza Humana/sangue , Influenza Humana/epidemiologia , Influenza Humana/transmissão , Masculino , Pessoa de Meia-Idade , Doenças das Aves Domésticas/sangue , Doenças das Aves Domésticas/epidemiologia , Doenças das Aves Domésticas/transmissão , População Rural/estatística & dados numéricos , Estudos Soroepidemiológicos , Vietnã , Adulto JovemRESUMO
UNLABELLED: The discovery of influenza virus broadly neutralizing (BrN) antibodies prompted efforts to develop universal vaccines. Influenza virus stem-reactive (SR) broadly neutralizing antibodies have been detected by screening antibody phage display libraries. However, studies of SR BrN antibodies in human serum, and their association with natural infection, are limited. To address this, pre- and postpandemic sera from a prospective community cohort study in Vietnam were assessed for antibodies that inhibit SR BrN monoclonal antibody (MAb) (C179) binding to H1N1 pandemic 2009 virus (H1N1pdm09). Of 270 households, 33 with at least one confirmed H1N1pdm09 illness or at least two seroconverters were included. The included households comprised 71 infected and 41 noninfected participants. Sera were tested as 2-fold dilutions between 1:5 and 1:40. Fifty percent C179 inhibition (IC50) titers did not exceed 10, although both IC50 titers and percent C179 inhibition by sera diluted 1:5 or 1:10 correlated with hemagglutination inhibition (HI) and microneutralization (MN) titers (all P < 0.001). Thirteen (12%) participants had detectable prepandemic IC50 titers, but only one reached a titer of 10. This proportion increased to 44% after the pandemic, when 39 participants had a titer of 10, and 67% of infected compared to 44% of noninfected had detectable IC50 titers (P < 0.001). The low levels of SR antibodies in prepandemic sera were not associated with subsequent H1N1pdm09 infection (P = 0.241), and the higher levels induced by H1N1pdm09 infection returned to prepandemic levels within 2 years. The findings indicate that natural infection induces only low titers of SR antibodies that are not sustained. IMPORTANCE: Universal influenza vaccines could have substantial health and economic benefits. The focus of universal vaccine research has been to induce antibodies that prevent infection by diverse influenza virus strains. These so-called broadly neutralizing antibodies are readily detected in mice and ferrets after infection with a series of distinct influenza virus strains. The 2009 H1N1 pandemic provided an opportunity to investigate whether infection with a novel strain induced broadly neutralizing antibodies in humans. We found that broadly neutralizing antibodies were induced, but levels were low and poorly maintained. This could represent an obstacle for universal vaccine development and warrants further investigation.
Assuntos
Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes/sangue , Anticorpos Antivirais/sangue , Glicoproteínas de Hemaglutininação de Vírus da Influenza/imunologia , Vírus da Influenza A Subtipo H1N1/imunologia , Influenza Humana/sangue , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Criança , Pré-Escolar , Feminino , Furões , Testes de Inibição da Hemaglutinação , Humanos , Lactente , Recém-Nascido , Influenza Humana/epidemiologia , Influenza Humana/imunologia , Influenza Humana/virologia , Masculino , Camundongos , Pessoa de Meia-Idade , Pandemias , Estudos Prospectivos , Fatores de Tempo , Vietnã/epidemiologia , Adulto JovemRESUMO
The nucleoprotein (NP) possesses regions that are highly conserved among influenza A viruses, and has therefore been one of the target viral proteins for development of a universal influenza vaccine. It has been expected that human or humanized antibodies will be made available for the prophylaxis, pre-emptive and acute treatment of viral infection. However, it is still unclear whether anti-NP human antibody can confer protection against influenza virus infection. In this study, we generated transgenic mice expressing anti-NP human mAbs derived from lymphocytes of a patient infected with H5N1 highly pathogenic avian influenza (HPAI) virus, and experimental infections were conducted to examine antiviral effects of the anti-NP antibodies against H5N1 HPAI viral infections with a high fatality rate in mammals. Transgenic mouse lines expressing the anti-NP human mAbs at more than 1 mg ml-1 showed marked resistance to H5N1 virus infections. In addition, resistance to infection with an H1N1 subtype that shows strong pathogenicity to mice was also confirmed. Although the anti-NP mAbs expressed in the transgenic mice did not neutralize the virus, the mAbs could bind to NP located on the surface of infected cells. These results suggested a possibility that the non-neutralizing anti-NP human mAbs could induce indirect antiviral effects, such as antibody-dependent cellular cytotoxicity or complement-dependent cytotoxicity. Taken together, these results demonstrated that anti-NP human mAbs play an important role in heterosubtypic protection against lethal influenza virus infections in vivo.
Assuntos
Anticorpos Monoclonais/imunologia , Anticorpos Antivirais/imunologia , Fatores Imunológicos/imunologia , Virus da Influenza A Subtipo H5N1/imunologia , Infecções por Orthomyxoviridae/imunologia , Proteínas de Ligação a RNA/imunologia , Proteínas do Core Viral/imunologia , Animais , Anticorpos Monoclonais/genética , Anticorpos Antivirais/genética , Modelos Animais de Doenças , Resistência à Doença , Humanos , Fatores Imunológicos/genética , Vírus da Influenza A Subtipo H1N1/imunologia , Camundongos , Camundongos Transgênicos , Proteínas do Nucleocapsídeo , Proteínas de Ligação a RNA/genética , Análise de Sobrevida , Proteínas do Core Viral/genéticaRESUMO
Dengue virus (DENV) is a mosquito-borne pathogen that annually infects more than 390 million people in 100 different countries. Symptoms of the viral infection include a relatively weak dengue fever to severe dengue hemorrhagic fever/dengue shock syndrome, which are mortal infectious diseases. As of yet, there is no commercially available vaccine or therapeutic for DENV. Currently, passive immunotherapy using DENV-specific antibody (Ab) is a considered strategy to treat DENV infection. Here, we developed a monoclonal Ab (mAb), EDIIImAb-61, specific to the DENV domain III of the envelope glycoprotein (EDIII) with broad-spectrum detection ability to all four DENV serotypes (DENV-1â¼4) to use as a therapeutic Ab. Although EDIII contains non-immunodominant epitopes compared to domains I and II, domain III plays a critical role in host receptor binding. EDIIImAb-61 exhibited cross-reactive binding affinity to all four DENV serotypes that had been isolated from infected humans. To further characterize EDIIImAb-61 and prepare genes for large-scale production using a heterologous expression system, the sequence of the complementarity determining regions was analyzed after cloning the full-length cDNA genes encoding the heavy and light chain of the mAb. Finally, we produced Ab from CHO-K1 cells transfected with the cloned EDIIImAb-61 heavy and light chain genes and confirmed the binding ability of the Ab. Collectively, we conclude that EDIIImAb-61 itself and the recombinant Ab produced using the cloned heavy and light chain gene of EDIIImAb-61 is a candidate for passive immunotherapy against DENV infection.
Assuntos
Anticorpos Monoclonais/genética , Anticorpos Monoclonais/imunologia , Vírus da Dengue/imunologia , Proteínas do Envelope Viral/metabolismo , Animais , Sítios de Ligação , Células CHO , Cricetulus , Vírus da Dengue/genética , Vírus da Dengue/isolamento & purificação , Desenho de Fármacos , Ligação Proteica , Engenharia de Proteínas , Sorogrupo , Proteínas do Envelope Viral/química , Proteínas do Envelope Viral/genéticaRESUMO
To guide control policies, it is important that the determinants of influenza transmission are fully characterized. Such assessment is complex because the risk of influenza infection is multifaceted and depends both on immunity acquired naturally or via vaccination and on the individual level of exposure to influenza in the community or in the household. Here, we analyse a large household cohort study conducted in 2007-2010 in Vietnam using innovative statistical methods to ascertain in an integrative framework the relative contribution of variables that influence the transmission of seasonal (H1N1, H3N2, B) and pandemic H1N1pdm09 influenza. Influenza infection was diagnosed by haemagglutination-inhibition (HI) antibody assay of paired serum samples. We used a Bayesian data augmentation Markov chain Monte Carlo strategy based on digraphs to reconstruct unobserved chains of transmission in households and estimate transmission parameters. The probability of transmission from an infected individual to another household member was 8% (95% CI, 6%, 10%) on average, and varied with pre-season titers, age and household size. Within households of size 3, the probability of transmission from an infected member to a child with low pre-season HI antibody titers was 27% (95% CI 21%-35%). High pre-season HI titers were protective against infection, with a reduction in the hazard of infection of 59% (95% CI, 44%-71%) and 87% (95% CI, 70%-96%) for intermediate (1â¶20-1â¶40) and high (≥1â¶80) HI titers, respectively. Even after correcting for pre-season HI titers, adults had half the infection risk of children. Twenty six percent (95% CI: 21%, 30%) of infections may be attributed to household transmission. Our results highlight the importance of integrated analysis by influenza sub-type, age and pre-season HI titers in order to infer influenza transmission risks in and outside of the household.
Assuntos
Influenza Humana/epidemiologia , Influenza Humana/transmissão , Adolescente , Adulto , Criança , Pré-Escolar , Estudos de Coortes , Características da Família , Feminino , Testes de Inibição da Hemaglutinação , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Estatísticos , Vietnã/epidemiologia , Adulto JovemRESUMO
Serological studies are the gold standard method to estimate influenza infection attack rates (ARs) in human populations. In a common protocol, blood samples are collected before and after the epidemic in a cohort of individuals; and a rise in haemagglutination-inhibition (HI) antibody titers during the epidemic is considered as a marker of infection. Because of inherent measurement errors, a 2-fold rise is usually considered as insufficient evidence for infection and seroconversion is therefore typically defined as a 4-fold rise or more. Here, we revisit this widely accepted 70-year old criterion. We develop a Markov chain Monte Carlo data augmentation model to quantify measurement errors and reconstruct the distribution of latent true serological status in a Vietnamese 3-year serological cohort, in which replicate measurements were available. We estimate that the 1-sided probability of a 2-fold error is 9.3% (95% Credible Interval, CI: 3.3%, 17.6%) when antibody titer is below 10 but is 20.2% (95% CI: 15.9%, 24.0%) otherwise. After correction for measurement errors, we find that the proportion of individuals with 2-fold rises in antibody titers was too large to be explained by measurement errors alone. Estimates of ARs vary greatly depending on whether those individuals are included in the definition of the infected population. A simulation study shows that our method is unbiased. The 4-fold rise case definition is relevant when aiming at a specific diagnostic for individual cases, but the justification is less obvious when the objective is to estimate ARs. In particular, it may lead to large underestimates of ARs. Determining which biological phenomenon contributes most to 2-fold rises in antibody titers is essential to assess bias with the traditional case definition and offer improved estimates of influenza ARs.
Assuntos
Anticorpos Antivirais/imunologia , Glicoproteínas de Hemaglutininação de Vírus da Influenza/imunologia , Influenza Humana/epidemiologia , Influenza Humana/imunologia , Adolescente , Adulto , Idoso , Anticorpos Antivirais/sangue , Estudos de Coortes , Feminino , Glicoproteínas de Hemaglutininação de Vírus da Influenza/sangue , Humanos , Influenza Humana/sangue , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Estudos Soroepidemiológicos , Testes Sorológicos , Vietnã/epidemiologiaRESUMO
OBJECTIVE: To characterize influenza seasonality and identify the best time of the year for vaccination against influenza in tropical and subtropical countries of southern and south-eastern Asia that lie north of the equator. METHODS: Weekly influenza surveillance data for 2006 to 2011 were obtained from Bangladesh, Cambodia, India, Indonesia, the Lao People's Democratic Republic, Malaysia, the Philippines, Singapore, Thailand and Viet Nam. Weekly rates of influenza activity were based on the percentage of all nasopharyngeal samples collected during the year that tested positive for influenza virus or viral nucleic acid on any given week. Monthly positivity rates were then calculated to define annual peaks of influenza activity in each country and across countries. FINDINGS: Influenza activity peaked between June/July and October in seven countries, three of which showed a second peak in December to February. Countries closer to the equator had year-round circulation without discrete peaks. Viral types and subtypes varied from year to year but not across countries in a given year. The cumulative proportion of specimens that tested positive from June to November was > 60% in Bangladesh, Cambodia, India, the Lao People's Democratic Republic, the Philippines, Thailand and Viet Nam. Thus, these tropical and subtropical countries exhibited earlier influenza activity peaks than temperate climate countries north of the equator. CONCLUSION: Most southern and south-eastern Asian countries lying north of the equator should consider vaccinating against influenza from April to June; countries near the equator without a distinct peak in influenza activity can base vaccination timing on local factors.
Assuntos
Influenza Humana/epidemiologia , Influenza Humana/virologia , Orthomyxoviridae/isolamento & purificação , Sudeste Asiático/epidemiologia , Humanos , Vacinas contra Influenza , Influenza Humana/prevenção & controle , Mucosa Nasal/virologia , Orthomyxoviridae/imunologia , Estações do Ano , Clima TropicalRESUMO
Manganese (Mn), an indispensable plant micronutrient, functions as a vital enzyme co-factor in numerous biochemical reactions. In rice, the Golgi-localized PHOTOSYNTHESIS-AFFECTED MUTANT 71-LIKE 3 (OsPML3), a member of the UNCHARACTERIZED PROTEIN FAMILY (UPF0016), plays a pivotal role in Mn homeostasis, particularly in rapidly developing tissues. This study focused on the functional characterization of another UPF0016 family member in rice, OsPML4, to elucidate its involvement in Mn homeostasis. OsPML4 had a 73% sequence identity with OsPML3 and exhibited expression in both shoots and roots, albeit at a lower transcriptional level than OsPML3. Furthermore, subcellular localization studies confirmed that OsPML4 localizes in the Golgi apparatus. Notably, heterologous expression of OsPML4 restored growth in the Mn uptake-deficient yeast strain Δsmf1 under Mn-limited conditions. Under Mn-deficient conditions, OsPML4 knockout exacerbated the decline in shoot dry weight and intensified necrosis in young leaves of OsPML3 knockout lines, which displayed stunted growth. The Mn concentration in OsPML3PML4 double knockout lines was lower than in wild-type (WT) and OsPML3 knockout lines. At the reproductive phase, OsPML3PML4 double knockout lines exhibited reduced fertility and grain yield compared to WT and OsPML3 knockout lines. Notably, reductions were observed in the deposition of cell wall polysaccharides and the content of Lea (Lewis A structure)-containing N-glycans in the young leaves of OsPML3PML4 double knockout lines, surpassing the reductions in WT and OsPML3 knockout lines. These findings underscore the significance of OsPML4 in Mn homeostasis in the Golgi apparatus, where it co-functions with OsPML3 to regulate cell wall polysaccharide deposition and late-stage Golgi N-glycosylation.
Assuntos
Proteínas de Transporte de Cátions , Oryza , Manganês/metabolismo , Oryza/genética , Oryza/metabolismo , Complexo de Golgi/metabolismo , Homeostase , Saccharomyces cerevisiae/metabolismo , Proteínas de Transporte de Cátions/metabolismoRESUMO
Objective: Human respiratory syncytial virus (RSV) is a primary cause of paediatric severe acute respiratory infection (SARI) worldwide, especially in developing countries. We investigated the genetic characteristics of RSV in northern Viet Nam to determine the prevalence and distribution of subtypes as well as the diversity and transmission patterns of genotypes. Methods: In two facilities, from January 2017 to December 2020, 1563 clinical specimens were collected from paediatric patients hospitalized with SARI and tested for RSV. Selected positive samples underwent sequencing analysis targeting the second hypervariable region of the G gene using next-generation sequencing. Results: The RSV positivity rate was 28.02% (438/1563 samples), and prevalence was highest in children aged < 1 year (43.84%; 192/438). Subtype RSV-A accounted for 53.42% (234/438) of cases, RSV-B for 45.89% (201/438), and there was coinfection in 0.68% (3/438). Both subtypes cocirculated and peaked during August-September in each year of the study. Phylogenetic analysis showed that RSV-A samples belonged to the ON1 genotype, which has three subgenotypes: ON1.1, ON1.2 and ON1.3. However, we did not find the 72-nucleotide duplication in the second hypervariable region of the G gene, a characteristic of genotype ON1, in any RSV-A samples. RSV-B samples belonged to genotype BA9. Discussion: Our results provide additional molecular characterization of RSV infections in Viet Nam. Specially, our study is the first to report the absence of the 72-nucleotide duplication in the G gene of RSV-A genotype ON1 in Viet Nam, which may help in understanding the genetic evolution of RSV and be useful for vaccine development in the future.
Assuntos
Infecções por Vírus Respiratório Sincicial , Vírus Sincicial Respiratório Humano , Criança , Humanos , Lactente , Vírus Sincicial Respiratório Humano/genética , Filogenia , Vietnã/epidemiologia , Infecções por Vírus Respiratório Sincicial/epidemiologia , Genótipo , NucleotídeosRESUMO
Prospective community-based studies have provided fundamental insights into the epidemiology of influenza in temperate regions, but few comparable studies have been undertaken in the tropics. The authors conducted prospective influenza surveillance and intermittent seroprevalence surveys in a household-based cohort in Vietnam between December 2007 and April 2010, resulting in 1,793 person-seasons of influenza surveillance. Age- and sex-standardized estimates of the risk of acquiring any influenza infection per season in persons 5 years of age or older were 21.1% (95% confidence interval: 17.4, 24.7) in season 1, 26.4% (95% confidence interval: 22.6, 30.2) in season 2, and 17.0% (95% confidence interval: 13.6, 20.4) in season 3. Some individuals experienced multiple episodes of infection with different influenza types/subtypes in the same season (n = 27) or reinfection with the same subtype in different seasons (n = 22). The highest risk of influenza infection was in persons 5-9 years old, in whom the risk of influenza infection per season was 41.8%. Although the highest infection risk was in school-aged children, there were important heterogeneities in the age of infection by subtype and season. These heterogeneities could influence the impact of school closure and childhood vaccination on influenza transmission in tropical areas, such as Vietnam.
Assuntos
Vírus da Influenza A Subtipo H1N1/isolamento & purificação , Influenza Humana/epidemiologia , Pandemias , Adolescente , Adulto , Fatores Etários , Idoso , Criança , Pré-Escolar , Feminino , Humanos , Incidência , Lactente , Recém-Nascido , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Vigilância da População , Estudos Prospectivos , RNA Viral/análise , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Risco , Estudos Soroepidemiológicos , Fatores Sexuais , Clima Tropical , Vietnã/epidemiologia , Adulto JovemRESUMO
The highly pathogenic avian influenza virus H5N1 is known to induce high level of tumor necrosis factor alpha (TNF-alpha) from primary macrophages. However, it is still unclear whether current H5N1 strains also induce high TNF-alpha production, as most of the data were derived from extinct clade 0 H5N1 strain. Here, we show that current clade 1 and 2 H5N1 strains induce variable levels of TNF-alpha that are not necessarily higher than those induced by seasonal influenza viruses. The result suggests that hyper-induction of TNF-alpha in human macrophages is not always associated with a highly pathogenic phenotype. We further tested the contribution of the NS gene segment from H5N1 isolates to TNF-alpha induction by using reverse genetics. While NS conferred some variation in TNF-alpha induction when incorporated into an H1N1 virus genetic background, it did not affect TNF-alpha induction in an H5N1 virus genetic background, suggesting that other viral genes are involved.
Assuntos
Vírus da Influenza A/imunologia , Influenza Aviária/virologia , Influenza Humana/virologia , Macrófagos/imunologia , Fator de Necrose Tumoral alfa/biossíntese , Animais , Aves/virologia , Humanos , Vírus da Influenza A Subtipo H1N1/imunologia , Vírus da Influenza A Subtipo H3N2/imunologia , Virus da Influenza A Subtipo H5N1/imunologia , Proteínas não Estruturais Virais/imunologiaRESUMO
Dengue virus (DENV) comprises four serotypes in the family Flaviviridae and is a causative agent of dengue-related diseases, including dengue fever. Dengue fever is generally a self-limited febrile illness. However, secondary infection of patients with a suboptimal antibody (Ab) response provokes life-threatening severe dengue hemorrhagic fever or dengue shock syndrome. To develop a potent candidate subunit vaccine against DENV infection, we developed the EDII-cEDIII antigen, which contains partial envelope domain II (EDII) including the fusion loop and BC loop epitopes together with consensus envelope domain III (cEDIII) of all four serotypes of DENV. We purified Ab from mice after immunization with EDII-cEDIII or cEDIII and compared their virus neutralization and Ab-dependent enhancement of DENV infection. Anti-EDII-cEDIII Ab showed stronger neutralizing activity and lower Ab-dependent peak enhancement of DENV infection compared with anti-cEDIII Ab. Following injection of Ab-treated DENV into AG129 mice, anti-EDII-cEDIII Ab ameliorated DENV infection in tissues with primary and secondary infection more effectively than anti-cEDIII Ab. In addition, anti-EDII-cEDIII Ab protected against DENV1, 2, and 4 challenge. We conclude that EDII-cEDIII induces neutralizing and protective Abs, and thus, shows promise as a candidate subunit vaccine for DENV infection.
RESUMO
BACKGROUND: The first cases of avian influenza A (H5N1) in humans in Vietnam were detected in early 2004, and Vietnam has reported the second highest number of cases globally. METHODS: We obtained retrospective clinical data through review of medical records for laboratory confirmed cases of influenza A (H5N1) infection diagnosed in Vietnam from January 2004 through December 2006. Standard data was abstracted regarding clinical and laboratory features, treatment, and outcome. RESULTS: Data were obtained for 67 (72%) of 93 cases diagnosed in Vietnam over the study period. Patients presented to the hospital after a median duration of illness of 6 days with fever (75%), cough (89%), and dyspnea (81%). Diarrhea and mucosal bleeding at presentation were more common in fatal than in nonfatal cases. Common findings were bilateral pulmonary infiltrates on chest radiograph (72%), lymphopenia (73%), and increased serum transaminase levels (aspartate aminotransferase, 69%; alanine aminotransferase, 61%). Twenty-six patients died (case fatality rate, 39%; 95% confidence interval, 27%-51%) and the most reliable predictor of a fatal outcome was the presence of both neutropenia and raised alanine aminotransferase level at admission, which correctly predicted 91% of deaths and 82% of survivals. The risk of death was higher among persons aged < or =16 years, compared with older persons (P < .001), and the risk of death was higher among patients who did not receive oseltamivir treatment (P = .048). The benefit of oseltamivir treatment remained after controlling for potential confounding by 1 measure of severity (odds ratio, 0.15; 95% confidence interval, 0.026-0.893; P = .034). CONCLUSION: In cases of infection with Influenza A (H5N1), the presence of both neutropenia and raised serum transaminase levels predicts a poor outcome. Oseltamivir treatment shows benefit, but treatment with corticosteroids is associated with an increased risk of death.
Assuntos
Virus da Influenza A Subtipo H5N1/isolamento & purificação , Influenza Humana/patologia , Adolescente , Adulto , Antivirais/uso terapêutico , Criança , Pré-Escolar , Diarreia/etiologia , Feminino , Hemorragia/etiologia , Humanos , Lactente , Influenza Humana/complicações , Influenza Humana/mortalidade , Influenza Humana/virologia , Pulmão/diagnóstico por imagem , Pulmão/patologia , Linfopenia/etiologia , Masculino , Pessoa de Meia-Idade , Oseltamivir/uso terapêutico , Radiografia , Estudos Retrospectivos , Fatores de Risco , Transaminases/sangue , Resultado do Tratamento , Vietnã , Adulto JovemRESUMO
H5N1 influenza A viruses are exacting a growing human toll, with more than 240 fatal cases to date. In the event of an influenza pandemic caused by these viruses, embryonated chicken eggs, which are the approved substrate for human inactivated-vaccine production, will likely be in short supply because chickens will be killed by these viruses or culled to limit the worldwide spread of the infection. The Madin-Darby canine kidney (MDCK) cell line is a promising alternative candidate substrate because it supports efficient growth of influenza viruses compared to other cell lines. Here, we addressed the molecular determinants for growth of an H5N1 vaccine seed virus in MDCK cells, revealing the critical responsibility of the Tyr residue at position 360 of PB2, the considerable requirement for functional balance between hemagglutinin (HA) and neuraminidase (NA), and the partial responsibility of the Glu residue at position 55 of NS1. Based on these findings, we produced a PR8/H5N1 reassortant, optimized for this cell line, that derives all of its genes for its internal proteins from the PR8(UW) strain except for the NS gene, which derives from the PR8(Cambridge) strain; its N1 NA gene, which has a long stalk and derives from an early H5N1 strain; and its HA gene, which has an avirulent-type cleavage site sequence and is derived from a circulating H5N1 virus. Our findings demonstrate the importance and feasibility of a cell culture-based approach to producing seed viruses for inactivated H5N1 vaccines that grow robustly and in a timely, cost-efficient manner as an alternative to egg-based vaccine production.
Assuntos
Virus da Influenza A Subtipo H5N1/crescimento & desenvolvimento , Vacinas contra Influenza , Animais , Técnicas de Cultura de Células , Linhagem Celular , Cães , Virus da Influenza A Subtipo H5N1/genética , Vírus Reordenados/genética , Vírus Reordenados/crescimento & desenvolvimento , Ensaio de Placa Viral , Proteínas Virais/genética , Proteínas Virais/fisiologia , Replicação ViralRESUMO
It is believed today that nucleocapsid protein (N) of severe acute respiratory syndrome (SARS)-CoV is one of the most promising antigen candidates for vaccine design. In this study, three fragments [N1 (residues: 1-422); N2 (residues: 1-109); N3 (residues: 110-422)] of N protein of SARS-CoV were expressed in Escherichia coli and analyzed by pooled sera of convalescence phase of SARS patients. Three gene fragments [N1 (1-1269 nt), N2 (1-327 nt) and N3 (328-1269 nt)-expressing the same proteins of N1, N2 and N3, respectively] of SARS-N were cloned into pVAX-1 and used to immunize BALB/c mice by electroporation. Humoral (by enzyme-linked immunosorbent assay, ELISA) and cellular (by cell proliferation and CD4(+):CD8(+) assay) immunity was detected by using recombinant N1 and N3 specific antigen. Results showed that N1 and N3 fragments of N protein expressed by E. coli were able to react with sera of SARS patients but N2 could not. Specific humoral and cellular immunity in mice could be induced significantly by inoculating SARS-CoV N1 and N3 DNA vaccine. In addition, the immune response levels in N3 were significantly higher for antibody responses (IgG and IgG1 but not IgG2a) and cell proliferation but not in CD4(+):CD8(+) assay compared to N1 vaccine. The identification of antigenic N protein fragments has implications to provide basic information for the design of DNA vaccine against SARS-CoV. The present results not only suggest that DNA immunization with pVax-N3 could be used as potential DNA vaccination approaches to induce antibody in BALB/c mice, but also illustrates that gene immunization with these SARS DNA vaccines can generate different immune responses.
Assuntos
Epitopos/imunologia , Nucleocapsídeo/imunologia , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/imunologia , Vacinas de DNA/imunologia , Vacinas Virais/imunologia , Animais , Anticorpos/imunologia , Linhagem Celular , Proliferação de Células , Escherichia coli/genética , Escherichia coli/metabolismo , Feminino , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Nucleocapsídeo/genética , Nucleocapsídeo/metabolismo , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/genética , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/metabolismo , Linfócitos T/citologia , Linfócitos T/imunologia , Vacinas de DNA/genética , Vacinas de DNA/metabolismo , Vacinas Virais/genética , Vacinas Virais/metabolismoRESUMO
Severe acute respiratory syndrome (SARS) is a lifethreatening emerging respiratory disease caused by the coronavirus, SARS-CoV. The nucleocapsid (N) protein of SARS-CoV is highly antigenic and may be a suitable candidate for diagnostic applications. We constructed truncated recombinant N proteins (N1 [1-422 aa], N2 [1- 109 aa], and N3 [110-422 aa]) and determined their antigenicity by Western blotting using convalescent SARS serum. The recombinants containing N1 and N3 reacted with convalescent SARS serum in Western blotting. However, the recombinant with N2 did not. In ELISA using N1 or N3 as the antigens, positive results were observed in 10 of 10 (100%) SARS-CoV-positive human sera. None of 50 healthy sera gave positive results in either assay. These data indicate that the ELISA using N1 or N3 has high sensitivity and specificity. These results suggest that the middle or C-terminal region of the SARS N protein is important for eliciting antibodies against SARS-CoV during the immune response, and ELISA reactions using N1 or N3 may be a valuable tool for SARS diagnosis.
Assuntos
Anticorpos Antivirais/sangue , Ensaio de Imunoadsorção Enzimática/métodos , Nucleocapsídeo/imunologia , Síndrome Respiratória Aguda Grave/imunologia , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/imunologia , Antígenos Virais/imunologia , Antígenos Virais/isolamento & purificação , Antígenos Virais/metabolismo , Expressão Gênica , Humanos , Nucleocapsídeo/isolamento & purificação , Nucleocapsídeo/metabolismo , Proteínas Recombinantes/imunologia , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Síndrome Respiratória Aguda Grave/diagnósticoRESUMO
Swine are an important intermediate host for emergence of pandemic influenza. Vietnam is the largest swine producer in South East Asia. Systematic virological and serological surveillance of swine influenza viruses was carried out in Northern Vietnam from May 2013 to June 2014 with monthly sampling of pigs in local and large collective slaughterhouses and in a live pig market. Influenza A seroprevalence in the local slaughterhouses and in the large collective slaughterhouse was 48.7% and 29.1%, respectively. Seventy-seven influenza A viruses were isolated, all from the large collective slaughterhouse. Genetic analysis revealed six virus genotypes including H1N1 2009 pandemic (H1N1pdm09) viruses, H1N2 with H1 of human origin, H3N2 and H1N1pdm09 reassortants, and triple-reassortant H3N2 viruses. Phylogenetic analysis of swine and human H1N1pdm09 viruses showed evidence of repeated spill-over from humans to swine rather than the establishment of H1N1pdm09 as long-term distinct lineage in swine. Surveillance at the large collective slaughterhouse proved to be the most efficient, cost-effective, and sustainable method of surveillance for swine influenza viruses in Vietnam.