RESUMO
Outbreaks of influenza in swine can result in potential threats to human public health. A notable occurrence was the emergence of swine-origin H1N1 influenza viruses in 2009. Since then, there have been several documented outbreaks of swine-origin influenza infecting humans in several countries. Sustained events have occurred when H1N1v, H1N2v, and H3N2v swine-origin viruses have infected humans visiting agricultural shows in the US. The predominant H3N2v viruses gained the matrix protein from the A(H1N1)pdm09 viruses, with reported human-to-human transmission raising fears of another pandemic. Current vaccines do not induce secondary cell-mediated immune responses, which may provide cross-protection against novel influenza A subtypes, however, population susceptibility to infection with seasonal influenza is likely to be influenced by cross-reactive CD8+ T-cells directed towards immunogenic peptides derived from viral proteins. This study involved a retrospective review of historical influenza viruses circulating in human populations from 1918 to 2020 to identify evidence of prior circulation of H3N3v immunogenic CD8+ T-cells peptides found in the NP and M1 proteins. We found evidence of prior circulation of H3N2v NP and M1 immunogenic peptides in historical influenza viruses. This provides insight into the population context in which influenza viruses emerge and may help inform immunogenic peptide selection for cytotoxic T-cell lymphocytes (CTL)-inducing influenza vaccines. Next-generation vaccines capable of eliciting CD8+ T-cell-mediated cross-protective immunity may offer a long-term alternative strategy for influenza vaccines.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Surtos de Doenças , Vírus da Influenza A Subtipo H3N2/imunologia , Influenza Humana/imunologia , Infecções por Orthomyxoviridae/imunologia , Linfócitos T Citotóxicos/imunologia , Adolescente , Adulto , Idoso , Animais , Linfócitos B/imunologia , Criança , Pré-Escolar , Proteção Cruzada , Feminino , Humanos , Lactente , Vírus da Influenza A Subtipo H3N2/genética , Influenza Humana/virologia , Masculino , Pessoa de Meia-Idade , Infecções por Orthomyxoviridae/virologia , Estudos Retrospectivos , Suínos , Adulto JovemRESUMO
BACKGROUND: Over the last two decades, Australia has experienced four severe influenza seasons caused by a predominance of influenza A (A/H3N2): 2003, 2007, 2012, and 2017. METHODS: We compared the epidemiology, genetics, and transmission dynamics of severe A/H3N2 seasons in Australia from 2003 to 2017. RESULTS: Since 2003, the proportion of notifications in 0-4 years old has decreased, while it has increased in the age group >80 years old (P < .001). The genetic diversity of circulating influenza A/H3N2 viruses has also increased over time with the number of single nucleotide polymorphisms significantly (P < .05) increasing. We also identified five residue positions within or near the receptor binding site of HA (144, 145, 159, 189, and 225) undergoing frequent mutations that are likely involved in significant antigenic drift and possibly severity. The Australian state of Victoria was identified as a frequent location for transmission either to or from other states and territories over the study years. The states of New South Wales and Queensland were also frequently implicated as locations of transmission to other states and territories but less so over the years. This indicates a stable but also changing dynamic of A/H3N2 circulation in Australia. CONCLUSION: These results have important implications for future influenza surveillance and control policy in the country. Reasons for the change in age-specific infection and increased genetic diversity of A/H3N2 viruses in recent years should be explored.
Assuntos
Vírus da Influenza A Subtipo H3N2/genética , Influenza Humana/epidemiologia , Influenza Humana/transmissão , Variação Antigênica , Austrália/epidemiologia , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Humanos , Vírus da Influenza A Subtipo H3N2/classificação , Vírus da Influenza A Subtipo H3N2/isolamento & purificação , Influenza Humana/virologia , Mutação , Filogenia , Filogeografia , Estações do AnoRESUMO
BackgroundInterseasonal influenza outbreaks are not unusual in countries with temperate climates and well-defined influenza seasons. Usually, these are small and diminish before the main influenza season begins. However, the 2018/19 summer-autumn interseasonal influenza period in Australia saw unprecedented large and widespread influenza outbreaks.AimOur objective was to determine the extent of the intense 2018/19 interseasonal influenza outbreaks in Australia epidemiologically and examine the genetic, antigenic and structural properties of the viruses responsible for these outbreaks.MethodsThis observational study combined the epidemiological and virological surveillance data obtained from the Australian Government Department of Health, the New South Wales Ministry of Health, sentinel outpatient surveillance, public health laboratories and data generated by the World Health Organization Collaborating Centre for Reference and Research on Influenza in Melbourne and the Singapore Agency for Science, Technology and Research.ResultsThere was a record number of laboratory-confirmed influenza cases during the interseasonal period November 2018 to May 2019 (n= 85,286; 5 times the previous 3-year average) and also more institutional outbreaks, hospitalisations and deaths, than what is normally seen.ConclusionsThe unusually large interseasonal influenza outbreaks in 2018/19 followed a mild 2018 influenza season and resulted in a very early start to the 2019 influenza season across Australia. The reasons for this unusual event have yet to be fully elucidated but are likely to be a complex mix of climatic, virological and host immunity-related factors. These outbreaks reinforce the need for year-round surveillance of influenza, even in temperate climates with strong seasonality patterns.
Assuntos
Notificação de Doenças/estatística & dados numéricos , Surtos de Doenças , Vírus da Influenza A/isolamento & purificação , Vírus da Influenza B/isolamento & purificação , Influenza Humana/epidemiologia , Vigilância da População/métodos , Adolescente , Adulto , Idoso , Austrália/epidemiologia , Criança , Pré-Escolar , Feminino , Hemaglutininas Virais , Humanos , Lactente , Vírus da Influenza A/classificação , Vírus da Influenza A/genética , Vírus da Influenza B/genética , Influenza Humana/diagnóstico , Influenza Humana/virologia , Masculino , Pessoa de Meia-Idade , New South Wales , Filogenia , Estações do Ano , Vigilância de Evento SentinelaRESUMO
BACKGROUND: Influenza virus circulation is monitored through the Cambodian influenza-like illness (ILI) sentinel surveillance system and isolates are characterized by the National Influenza Centre (NIC). Seasonal influenza circulation has previously been characterized by year-round activity and a peak during the rainy season (June-November). OBJECTIVES: We documented the circulation of seasonal influenza in Cambodia for 2012-2015 and investigated genetic, antigenic, and antiviral resistance characteristics of influenza isolates. PATIENTS/METHODS: Respiratory samples were collected from patients presenting with influenza-like illness (ILI) at 11 hospitals throughout Cambodia. First-line screening was conducted by the National Institute of Public Health and the Armed Forces Research Institute of Medical Sciences. Confirmation of testing and genetic, antigenic and antiviral resistance characterization was conducted by Institute Pasteur in Cambodia, the NIC. Additional virus characterization was conducted by the WHO Collaborating Centre for Reference and Research on Influenza (Melbourne, Australia). RESULTS: Between 2012 and 2015, 1,238 influenza-positive samples were submitted to the NIC. Influenza A(H3N2) (55.3%) was the dominant subtype, followed by influenza B (30.9%; predominantly B/Yamagata-lineage) and A(H1N1)pdm09 (13.9%). Circulation of influenza viruses began earlier in 2014 and 2015 than previously described, coincident with the emergence of A(H3N2) clades 3C.2a and 3C.3a, respectively. There was high diversity in the antigenicity of A(H3N2) viruses, and to a smaller extent influenza B viruses, during this period, with some mismatches with the northern and southern hemisphere vaccine formulations. All isolates tested were susceptible to the influenza antiviral drugs oseltamivir and zanamivir. CONCLUSIONS: Seasonal and year-round co-circulation of multiple influenza types/subtypes were detected in Cambodia during 2012-2015.
Assuntos
Farmacorresistência Viral , Vírus da Influenza A/isolamento & purificação , Vírus da Influenza B/isolamento & purificação , Estações do Ano , Vigilância de Evento Sentinela , Adolescente , Adulto , Idoso , Antivirais/uso terapêutico , Camboja/epidemiologia , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Vírus da Influenza A/genética , Vírus da Influenza B/genética , Vacinas contra Influenza/uso terapêutico , Influenza Humana/tratamento farmacológico , Influenza Humana/epidemiologia , Masculino , Pessoa de Meia-Idade , Sequenciamento Completo do Genoma , Adulto JovemRESUMO
Global swine populations infected with influenza A viruses pose a persistent pandemic risk. With the exception of a few countries, our understanding of the genetic diversity of swine influenza viruses is limited, hampering control measures and pandemic risk assessment. Here we report the genomic characteristics and evolutionary history of influenza A viruses isolated in Australia from 2012 to 2016 from two geographically isolated swine populations in the states of Queensland and Western Australia. Phylogenetic analysis with an expansive human and swine influenza virus data set comprising >40,000 sequences sampled globally revealed evidence of the pervasive introduction and long-term establishment of gene segments derived from several human influenza viruses of past seasons, including the H1N1/1977, H1N1/1995, H3N2/1968, and H3N2/2003, and the H1N1 2009 pandemic (H1N1pdm09) influenza A viruses, and a genotype that contained gene segments derived from the past three pandemics (1968, reemerged 1977, and 2009). Of the six human-derived gene lineages, only one, comprising two viruses isolated in Queensland during 2012, was closely related to swine viruses detected from other regions, indicating a previously undetected circulation of Australian swine lineages for approximately 3 to 44 years. Although the date of introduction of these lineages into Australian swine populations could not be accurately ascertained, we found evidence of sustained transmission of two lineages in swine from 2012 to 2016. The continued detection of human-origin influenza virus lineages in swine over several decades with little or unpredictable antigenic drift indicates that isolated swine populations can act as antigenic archives of human influenza viruses, raising the risk of reemergence in humans when sufficient susceptible populations arise.IMPORTANCE We describe the evolutionary origins and antigenic properties of influenza A viruses isolated from two separate Australian swine populations from 2012 to 2016, showing that these viruses are distinct from each other and from those isolated from swine globally. Whole-genome sequencing of virus isolates revealed a high genotypic diversity that had been generated exclusively through the introduction and establishment of human influenza viruses that circulated in past seasons. We detected six reassortants with gene segments derived from human H1N1/H1N1pdm09 and various human H3N2 viruses that circulated during various periods since 1968. We also found that these swine viruses were not related to swine viruses collected elsewhere, indicating independent circulation. The detection of unique lineages and genotypes in Australia suggests that isolated swine populations that are sufficiently large can sustain influenza virus for extensive periods; we show direct evidence of a sustained transmission for at least 4 years between 2012 and 2016.
Assuntos
Variação Genética , Vírus da Influenza A/classificação , Vírus da Influenza A/isolamento & purificação , Infecções por Orthomyxoviridae/veterinária , Doenças dos Suínos/virologia , Suínos/virologia , Animais , Genótipo , Humanos , Vírus da Influenza A/genética , Epidemiologia Molecular , Infecções por Orthomyxoviridae/epidemiologia , Infecções por Orthomyxoviridae/virologia , Filogenia , Queensland/epidemiologia , Doenças dos Suínos/epidemiologia , Austrália Ocidental/epidemiologiaRESUMO
In 2017, influenza seasonal activity was high in the southern hemisphere. We present interim influenza vaccine effectiveness (VE) estimates from Australia. Adjusted VE was low overall at 33% (95% confidence interval (CI): 17 to 46), 50% (95% CI: 8 to 74) for A(H1)pdm09, 10% (95% CI: -16 to 31) for A(H3) and 57% (95% CI: 41 to 69) for influenza B. For A(H3), VE was poorer for those vaccinated in the current and prior seasons.
Assuntos
Vírus da Influenza A Subtipo H1N1/imunologia , Vírus da Influenza A Subtipo H3N2/imunologia , Vírus da Influenza B/imunologia , Vacinas contra Influenza/administração & dosagem , Influenza Humana/epidemiologia , Influenza Humana/prevenção & controle , Vigilância de Evento Sentinela , Potência de Vacina , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Austrália/epidemiologia , Criança , Pré-Escolar , Feminino , Humanos , Vírus da Influenza A Subtipo H1N1/genética , Vírus da Influenza A Subtipo H1N1/isolamento & purificação , Vírus da Influenza A Subtipo H3N2/genética , Vírus da Influenza A Subtipo H3N2/isolamento & purificação , Vírus da Influenza B/genética , Vírus da Influenza B/isolamento & purificação , Vacinas contra Influenza/imunologia , Influenza Humana/virologia , Laboratórios , Masculino , Pessoa de Meia-Idade , Avaliação de Resultados em Cuidados de Saúde , RNA Viral/genética , Estações do Ano , Análise de Sequência de DNA , Vacinação/estatística & dados numéricos , Vacinas de Produtos Inativados/administração & dosagem , Vacinas de Produtos Inativados/imunologia , Adulto JovemRESUMO
For over a decade virtually all A(H3N2) influenza viruses have been resistant to the adamantane class of antivirals. However, during the 2017 influenza season in Australia, 15/461 (3.3%) adamantane-sensitive A(H3N2) viruses encoding serine at residue 31 of the M2 protein were detected, more than the total number identified globally during the last 6 years. A return to wide circulation of adamantane-sensitive A(H3N2) viruses would revive the option of using these drugs for treatment and prophylaxis.
Assuntos
Adamantano/farmacologia , Antivirais/farmacologia , Farmacorresistência Viral/genética , Vírus da Influenza A Subtipo H3N2/efeitos dos fármacos , Influenza Humana/tratamento farmacológico , Influenza Humana/virologia , Substituição de Aminoácidos , Austrália/epidemiologia , Genoma Viral , Humanos , Vírus da Influenza A Subtipo H3N2/genética , Vírus da Influenza A Subtipo H3N2/isolamento & purificação , Influenza Humana/epidemiologia , Filogenia , RNA Viral , Estações do Ano , Análise de Sequência de DNARESUMO
Current seasonal influenza vaccines require regular updates due to antigenic drift causing loss of effectiveness and therefore providing little or no protection against novel influenza A subtypes. Next generation vaccines capable of eliciting CD8(+) T cell (CTL) mediated cross-protective immunity may offer a long-term alternative strategy. However, measuring pre- and existing levels of CTL cross-protection in humans is confounded by differences in infection histories across individuals. During 2000-2003, H1N2 viruses circulated persistently in the human population for the first time and we hypothesized that the viral nucleoprotein (NP) contained novel CTL epitopes that may have contributed to the survival of the viruses. This study describes the immunogenic NP peptides of H1N1, H2N2, and H3N2 influenza viruses isolated from humans over the past century, 1918-2003, by comparing this historical dataset to reference NP peptides from H1N2 that circulated in humans during 2000-2003. Observed peptides sequences ranged from highly conserved (15%) to highly variable (12%), with variation unrelated to reported immunodominance. No unique NP peptides which were exclusive to the H1N2 viruses were noted. However, the virus had inherited the NP from a recently emerged H3N2 variant containing novel peptides, which may have assisted its persistence. Any advantage due to this novelty was subsequently lost with emergence of a newer H3N2 variant in 2003. Our approach has potential to provide insight into the population context in which influenza viruses emerge, and may help to inform immunogenic peptide selection for CTL-inducing influenza vaccines. J. Med. Virol. 88:1725-1732, 2016. © 2016 Wiley Periodicals, Inc.
Assuntos
Proteção Cruzada , Epitopos de Linfócito T , Vírus da Influenza A Subtipo H1N2/genética , Vírus da Influenza A Subtipo H1N2/imunologia , Animais , Anticorpos Antivirais/imunologia , Humanos , Vírus da Influenza A Subtipo H1N1/química , Vírus da Influenza A Subtipo H1N1/imunologia , Vírus da Influenza A Subtipo H3N2/química , Vírus da Influenza A Subtipo H3N2/imunologia , Influenza Humana/imunologia , Proteínas do Nucleocapsídeo , Infecções por Orthomyxoviridae/imunologia , Infecções por Orthomyxoviridae/virologia , Peptídeos/imunologia , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/imunologia , Linfócitos T Citotóxicos/imunologia , Proteínas do Core Viral/genética , Proteínas do Core Viral/imunologiaRESUMO
The factors that determine the characteristic seasonality of influenza remain enigmatic. Current models predict that occurrences of influenza outside the normal surveillance season within a temperate region largely reflect the importation of viruses from the alternate hemisphere or from equatorial regions in Asia. To help reveal the drivers of seasonality we investigated the origins and evolution of influenza viruses sampled during inter-seasonal periods in Australia. To this end we conducted an expansive phylogenetic analysis of 9912, 3804, and 3941 hemagglutinnin (HA) sequences from influenza A/H1N1pdm, A/H3N2, and B, respectively, collected globally during the period 2009-2014. Of the 1475 viruses sampled from Australia, 396 (26.8% of Australian, or 2.2% of global set) were sampled outside the monitored temperate influenza surveillance season (1 May - 31 October). Notably, rather than simply reflecting short-lived importations of virus from global localities with higher influenza prevalence, we documented a variety of more complex inter-seasonal transmission patterns including "stragglers" from the preceding season and "heralds" of the forthcoming season, and which included viruses sampled from clearly temperate regions within Australia. We also provide evidence for the persistence of influenza B virus between epidemic seasons, in which transmission of a viral lineage begins in one season and continues throughout the inter-seasonal period into the following season. Strikingly, a disproportionately high number of inter-seasonal influenza transmission events occurred in tropical and subtropical regions of Australia, providing further evidence that climate plays an important role in shaping patterns of influenza seasonality.
Assuntos
Surtos de Doenças , Vírus da Influenza B/isolamento & purificação , Influenza Humana/epidemiologia , Influenza Humana/virologia , Austrália , Clima , Humanos , Vírus da Influenza A Subtipo H1N1/genética , Vírus da Influenza A Subtipo H1N1/isolamento & purificação , Vírus da Influenza A Subtipo H3N2/genética , Vírus da Influenza A Subtipo H3N2/isolamento & purificação , Vírus da Influenza B/genética , Estações do Ano , Análise de Sequência de DNA/métodosRESUMO
BACKGROUND: The Cambodian National Influenza Center (NIC) monitored and characterized circulating influenza strains from 2009 to 2011. METHODOLOGY/PRINCIPAL FINDINGS: Sentinel and study sites collected nasopharyngeal specimens for diagnostic detection, virus isolation, antigenic characterization, sequencing and antiviral susceptibility analysis from patients who fulfilled case definitions for influenza-like illness, acute lower respiratory infections and event-based surveillance. Each year in Cambodia, influenza viruses were detected mainly from June to November, during the rainy season. Antigenic analysis show that A/H1N1pdm09 isolates belonged to the A/California/7/2009-like group. Circulating A/H3N2 strains were A/Brisbane/10/2007-like in 2009 before drifting to A/Perth/16/2009-like in 2010 and 2011. The Cambodian influenza B isolates from 2009 to 2011 all belonged to the B/Victoria lineage represented by the vaccine strains B/Brisbane/60/2008 and B/Malaysia/2506/2004. Sequences of the M2 gene obtained from representative 2009-2011 A/H3N2 and A/H1N1pdm09 strains all contained the S31N mutation associated with adamantanes resistance except for one A/H1N1pdm09 strain isolated in 2011 that lacked this mutation. No reduction in the susceptibility to neuraminidase inhibitors was observed among the influenza viruses circulating from 2009 to 2011. Phylogenetic analysis revealed that A/H3N2 strains clustered each year to a distinct group while most A/H1N1pdm09 isolates belonged to the S203T clade. CONCLUSIONS/SIGNIFICANCE: In Cambodia, from 2009 to 2011, influenza activity occurred throughout the year with peak seasonality during the rainy season from June to November. Seasonal influenza epidemics were due to multiple genetically distinct viruses, even though all of the isolates were antigenically similar to the reference vaccine strains. The drug susceptibility profile of Cambodian influenza strains revealed that neuraminidase inhibitors would be the drug of choice for influenza treatment and chemoprophylaxis in Cambodia, as adamantanes are no longer expected to be effective.
Assuntos
Influenza Humana/epidemiologia , Influenza Humana/virologia , Orthomyxoviridae/fisiologia , Animais , Antígenos Virais/imunologia , Camboja/epidemiologia , Cães , Farmacorresistência Viral , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Humanos , Vírus da Influenza A Subtipo H1N1/genética , Vírus da Influenza A Subtipo H1N1/isolamento & purificação , Vírus da Influenza A Subtipo H3N2/genética , Vírus da Influenza A Subtipo H3N2/isolamento & purificação , Vírus da Influenza B/genética , Vírus da Influenza B/isolamento & purificação , Vacinas contra Influenza/imunologia , Influenza Humana/imunologia , Células Madin Darby de Rim Canino , Orthomyxoviridae/imunologia , Orthomyxoviridae/isolamento & purificação , Filogenia , Estações do AnoRESUMO
The emergence and transition to pandemic status of the influenza A(H1N1)A(H1N1)pdm09) virus in 2009 illustrated the potential for previously circulating human viruses to re-emerge in humans and cause a pandemic after decades of circulating among animals. Within a short time of the initial emergence of A(H1N1)pdm09 virus, novel reassortants were isolated from swine. In late 2011, a variant (v) H3N2 subtype was isolated from humans, and by 2012, the number of persons infected began to increase with limited person-to-person transmission. During 2012 in the United States, an A(H1N2)v virus was transmitted to humans from swine. During the same year, Australia recorded its first H1N2 subtype infection among swine. The A(H3N2)v and A(H1N2)v viruses contained the matrix protein from the A(H1N1)pdm09 virus, raising the possibility of increased transmissibility among humans and underscoring the potential for influenza pandemics of novel swine-origin viruses. We report on the differing histories of A(H1N2) viruses among humans and animals.
Assuntos
Vírus da Influenza A Subtipo H1N2/classificação , Influenza Humana/epidemiologia , Influenza Humana/história , Animais , Evolução Molecular , História do Século XX , História do Século XXI , Humanos , Vírus da Influenza A Subtipo H1N1/genética , Vírus da Influenza A Subtipo H1N1/isolamento & purificação , Vírus da Influenza A Subtipo H1N2/genética , Vírus da Influenza A Subtipo H1N2/isolamento & purificação , Vírus da Influenza A Subtipo H3N2/genética , Vírus da Influenza A Subtipo H3N2/isolamento & purificação , Vírus da Influenza A , Influenza Humana/transmissão , Infecções por Orthomyxoviridae , Vírus Reordenados/classificação , Vírus Reordenados/genética , Vírus Reordenados/isolamento & purificação , SuínosRESUMO
Vaccine effectiveness may wane with increasing time since vaccination. This analysis used the Victorian sentinel general practitioner (GP) network to estimate vaccine effectiveness for trivalent inactivated vaccines in the 2012 season. A test-negative design was used where patients presenting to GPs with influenza-like illness who tested positive for influenza were cases and noncases were those who tested negative. Vaccination status was recorded by GPs. Vaccine effectiveness was calculated as (1-odds ratio) × 100%. Estimates were compared early versus late in the season and by time since vaccination. Virus isolates were assessed antigenically by hemagglutination inhibition assay in a selection of positive samples and viruses from healthy adults who experienced a vaccine breakthrough were analyzed genetically. The adjusted vaccine effectiveness estimate for any type of influenza was 45% (95% CI: 8,66) and for influenza A(H3) was 35% (95% CI: -11,62). A non-significant effect of waning effectiveness by time since vaccination was observed for A(H3). For those vaccinated <93 days of presentation vaccine effectiveness was 37% (95% CI: -29,69), while for those vaccinated ≥93 days before presentation it was 18% (95% CI: -83,63). Comparison of early versus late in the season estimates was very sensitive to the cut off week chosen for analysis. Antigenic data suggested that low vaccine effectiveness was not associated with poor vaccine match among the A(H3) viruses. However, genetic analysis suggested nucleotide substitutions in antigenic sites. In 2012, the trivalent influenza vaccine provided moderate protection against influenza and showed limited evidence for waning effectiveness. Antigenic and genetic data can provide additional insight into understanding these estimates.
Assuntos
Vacinas contra Influenza/administração & dosagem , Vacinas contra Influenza/imunologia , Influenza Humana/epidemiologia , Influenza Humana/prevenção & controle , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Substituição de Aminoácidos , Antígenos Virais/genética , Antígenos Virais/imunologia , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Vírus da Influenza A/imunologia , Vírus da Influenza A/isolamento & purificação , Influenza Humana/imunologia , Masculino , Pessoa de Meia-Idade , Vigilância de Evento Sentinela , Fatores de Tempo , Resultado do Tratamento , Vitória/epidemiologia , Adulto JovemRESUMO
Influenza A virus-specific CD8(+) cytotoxic T lymphocytes (CTLs) provide a degree of cross-strain protection that is potentially subverted by mutation. Here we describe the sequential emergence of such variants within CTL epitopes for a persistently infected, immunocompromised infant. Further analysis in immunodeficient and wild-type mice supports the view that CTL escape variants arise frequently in influenza, accumulate with time and revert in the absence of immune pressure under MHCI-mismatched conditions. Viral fitness, the abundance of endogenous CD8(+) T cell responses and T cell receptor repertoire diversity influence the nature of these de novo mutants. Structural characterization of dominant escape variants shows how the peptide-MHCI interaction is modified to affect variant-MHCI stability. The mechanism of influenza virus escape thus looks comparable to that recognized for chronic RNA viruses like HIV and HCV, suggesting that immunocompromised patients with prolonged viral infection could have an important part in the emergence of influenza quasispecies.
Assuntos
Antígenos Virais/imunologia , Linfócitos T CD8-Positivos/imunologia , Epitopos de Linfócito T/imunologia , Hospedeiro Imunocomprometido , Vírus da Influenza A Subtipo H3N2/genética , Influenza Humana/imunologia , Linfócitos T Citotóxicos/imunologia , Sequência de Aminoácidos , Animais , Antígenos Virais/genética , Linfócitos T CD8-Positivos/patologia , Linfócitos T CD8-Positivos/virologia , Epitopos de Linfócito T/genética , Expressão Gênica/imunologia , Antígenos de Histocompatibilidade Classe I/genética , Antígenos de Histocompatibilidade Classe I/imunologia , Humanos , Evasão da Resposta Imune , Lactente , Vírus da Influenza A Subtipo H3N2/imunologia , Influenza Humana/patologia , Influenza Humana/virologia , Camundongos , Camundongos Endogâmicos BALB C , Dados de Sequência Molecular , Mutação , Peptídeos/genética , Peptídeos/imunologia , Receptores de Antígenos de Linfócitos T/genética , Receptores de Antígenos de Linfócitos T/imunologia , Linfócitos T Citotóxicos/patologia , Linfócitos T Citotóxicos/virologiaRESUMO
BACKGROUND: Influenza B viruses belong to two antigenically and genetically distinct lineages which co-circulate in varying proportions in many countries. OBJECTIVE: To develop simple, rapid, accurate and robust methods to detect and differentiate currently circulating B-lineage viruses in respiratory samples and virus isolates. STUDY DESIGN: Haemagglutinin (HA) gene sequences from more than 6300 influenza B strains were analysed to identify signature sequences that could be used to distinguish between B-lineages and sublineages. RESULTS: Pyrosequencing and a real time PCR assays were developed to detect the major B-lineages (B/Victoria/2/87 or B/Yamagata/16/88) and pyrosequencing for a unique mutation was used to further differentiate the B/Yamagata viruses into two currently co-circulating subgroups. More than 300 influenza virus-containing samples, including original specimens, cell and egg grown viruses, were tested with a 100% accuracy. Furthermore, when the same PCR primers were used in an rRT-PCR assay, the two lineages could be differentiated by their distinct ranges of melting temperature with an overall accuracy of 99% for 158 samples tested. CONCLUSIONS: These new pyrosequencing and rRT-PCR methods have the potential to aid the rapid identification of influenza B-lineages for surveillance purposes and to increase the available data for bi-annual selection of viruses for updating influenza vaccines.
Assuntos
Vírus da Influenza B/classificação , Vírus da Influenza B/genética , Influenza Humana/virologia , Reação em Cadeia da Polimerase em Tempo Real/métodos , Análise de Sequência de DNA/métodos , Virologia/métodos , Genótipo , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Humanos , Epidemiologia Molecular/métodos , Sensibilidade e EspecificidadeRESUMO
Despite greater than 99% of influenza A viruses circulating in the Asia-Pacific region being resistant to the adamantane antiviral drugs in 2011, the large majority of influenza A (>97%) and B strains (â¼99%) remained susceptible to the neuraminidase inhibitors oseltamivir and zanamivir. However, compared to the first year of the 2009 pandemic, cases of oseltamivir-resistant A(H1N1)pdm09 viruses with the H275Y neuraminidase mutation increased in 2011, primarily due to an outbreak of oseltamivir-resistant viruses that occurred in Newcastle, as reported in Hurt et al. (2011c, 2012a), where the majority of the resistant viruses were from community patients not being treated with oseltamivir. A small number of influenza B viruses with reduced oseltamivir or zanamivir susceptibility were also detected. The increased detection of neuraminidase inhibitor resistant strains circulating in the community and the detection of novel variants with reduced susceptibility are reminders that monitoring of influenza viruses is important to ensure that antiviral treatment guidelines remain appropriate.
Assuntos
Antivirais/farmacologia , Vírus da Influenza A/efeitos dos fármacos , Vírus da Influenza B/efeitos dos fármacos , Influenza Humana/virologia , Ásia , Humanos , Vírus da Influenza A/isolamento & purificação , Vírus da Influenza B/isolamento & purificação , Concentração Inibidora 50 , Testes de Sensibilidade Microbiana , Ilhas do PacíficoRESUMO
BACKGROUND: Swine have receptors for both human and avian influenza viruses and are a natural host for influenza A viruses. The 2009 influenza A(H1N1) pandemic (H1N1pdm) virus that was derived from avian, human and swine influenza viruses has infected pigs in various countries. OBJECTIVES: To investigate the relationship between the H1N1pdm viruses isolated from piggery outbreaks in Australia and human samples associated with one of the outbreaks by phylogenetic analysis, and to determine whether there was any reassortment event occurring during the human-pig interspecies transmission. METHODS: Real-time RT-PCR and full genome sequencing were carried out on RNA isolated from nasal swabs and/or virus cultures. Phylogenetic analysis was performed using the Geneious package. RESULTS: The influenza H1N1pdm outbreaks were detected in three pig farms located in three different states in Australia. Further analysis of the Queensland outbreak led to the identification of two distinct virus strains in the pigs. Two staff working in the same piggery were also infected with the same two strains found in the pigs. Full genome sequence analysis on the viruses isolated from pigs and humans did not identify any reassortment of these H1N1pdm viruses with seasonal or avian influenza A viruses. CONCLUSIONS: This is the first report of swine infected with influenza in Australia and marked the end of the influenza-free era for the Australian swine industry. Although no reassortment was detected in these cases, the ability of these viruses to cross between pigs and humans highlights the importance of monitoring swine for novel influenza infections.
Assuntos
Vírus da Influenza A Subtipo H1N1/isolamento & purificação , Influenza Humana/transmissão , Influenza Humana/virologia , Infecções por Orthomyxoviridae/veterinária , Doenças dos Suínos/transmissão , Doenças dos Suínos/virologia , Animais , Austrália/epidemiologia , Surtos de Doenças , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Humanos , Vírus da Influenza A Subtipo H1N1/classificação , Vírus da Influenza A Subtipo H1N1/genética , Influenza Humana/epidemiologia , Dados de Sequência Molecular , Infecções por Orthomyxoviridae/epidemiologia , Infecções por Orthomyxoviridae/transmissão , Infecções por Orthomyxoviridae/virologia , Pandemias/veterinária , Filogenia , Suínos , Doenças dos Suínos/epidemiologiaRESUMO
The neuraminidase inhibitors (NAIs) are an effective class of antiviral drugs for the treatment of influenza A and B infections. Until recently, only a low prevalence of NAI resistance (<1%) had been detected in circulating viruses. However, surveillance in Europe in late 2007 revealed significant numbers of A(H1N1) influenza strains with a H274Y neuraminidase mutation that were highly resistant to the NAI oseltamivir. We examined 264 A(H1N1) viruses collected in 2008 from South Africa, Oceania and SE Asia for their susceptibility to NAIs oseltamivir, zanamivir and peramivir in a fluorescence-based neuraminidase inhibition assay. Viruses with reduced oseltamivir susceptibility were further analysed by pyrosequencing assay. The frequency of the oseltamivir-resistant H274Y mutant increased significantly after May 2008, resulting in an overall proportion of 64% (168/264) resistance among A(H1N1) strains, although this subtype represented only 11.6% of all isolates received during 2008. H274Y mutant viruses demonstrated on average a 1466-fold reduction in oseltamivir susceptibility and 527-fold reduction in peramivir sensitivity compared to wild-type A(H1N1) viruses. The mutation had no impact on zanamivir susceptibility. Ongoing surveillance is essential to monitor how these strains may spread or persist in the future and to evaluate the effectiveness of treatments against them.
Assuntos
Antivirais/farmacologia , Farmacorresistência Viral , Vírus da Influenza A Subtipo H1N1/efeitos dos fármacos , Influenza Humana/virologia , Oseltamivir/farmacologia , Ácidos Carbocíclicos , Substituição de Aminoácidos/genética , Sudeste Asiático , Análise por Conglomerados , Ciclopentanos/farmacologia , Guanidinas/farmacologia , Humanos , Vírus da Influenza A Subtipo H1N1/isolamento & purificação , Testes de Sensibilidade Microbiana , Mutação de Sentido Incorreto , Neuraminidase/genética , Neuraminidase/metabolismo , Oceania , Filogenia , RNA Viral/genética , Análise de Sequência de DNA , Homologia de Sequência , África do Sul , Proteínas Virais/genética , Proteínas Virais/metabolismo , Zanamivir/farmacologiaRESUMO
Antigenic and genetic analysis of the hemagglutinin of approximately 13,000 human influenza A (H3N2) viruses from six continents during 2002-2007 revealed that there was continuous circulation in east and Southeast Asia (E-SE Asia) via a region-wide network of temporally overlapping epidemics and that epidemics in the temperate regions were seeded from this network each year. Seed strains generally first reached Oceania, North America, and Europe, and later South America. This evidence suggests that once A (H3N2) viruses leave E-SE Asia, they are unlikely to contribute to long-term viral evolution. If the trends observed during this period are an accurate representation of overall patterns of spread, then the antigenic characteristics of A (H3N2) viruses outside E-SE Asia may be forecast each year based on surveillance within E-SE Asia, with consequent improvements to vaccine strain selection.
Assuntos
Surtos de Doenças , Glicoproteínas de Hemaglutininação de Vírus da Influenza/imunologia , Vírus da Influenza A Subtipo H3N2 , Influenza Humana/epidemiologia , Variação Antigênica , Ásia/epidemiologia , Sudeste Asiático/epidemiologia , Europa (Continente)/epidemiologia , Evolução Molecular , Previsões , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Humanos , Vírus da Influenza A Subtipo H3N2/classificação , Vírus da Influenza A Subtipo H3N2/genética , Vírus da Influenza A Subtipo H3N2/imunologia , Vírus da Influenza A Subtipo H3N2/isolamento & purificação , Vacinas contra Influenza , Influenza Humana/virologia , América do Norte/epidemiologia , Oceania , Filogenia , Vigilância da População , Estações do Ano , América do Sul/epidemiologiaRESUMO
Annual influenza epidemics in humans affect 5-15% of the population, causing an estimated half million deaths worldwide per year [Stohr K. Influenza-WHO cares. Lancet Infectious Diseases 2002;2(9):517]. The virus can infect this proportion of people year after year because the virus has an extensive capacity to evolve and thus evade the immune response. For example, since the influenza A(H3N2) subtype entered the human population in 1968 the A(H3N2) component of the influenza vaccine has had to be updated almost 30 times to track the evolution of the viruses and remain effective. The World Health Organization Global Influenza Surveillance Network (WHO GISN) tracks and analyzes the evolution and epidemiology of influenza viruses for the primary purpose of vaccine strain selection and to improve the strain selection process through studies aimed at better understanding virus evolution and epidemiology. Here we give an overview of the strain selection process and outline recent investigations into the global migration of seasonal influenza viruses.
Assuntos
Vírus da Influenza A Subtipo H3N2/imunologia , Vacinas contra Influenza/imunologia , Influenza Humana/epidemiologia , Influenza Humana/prevenção & controle , HumanosRESUMO
During annual influenza epidemics, influenza B viruses frequently co-circulate with influenza A viruses and in some years, such as 2005, large outbreaks have occurred while in other years, the virus virtually disappears. Since 1987 there have been two lineages of influenza B viruses co-circulating in various countries and causing disease in humans. The proportions of these two lineages vary from year to year and country to country. For example, in 2005, the B/Victoria/2/87 lineage was predominant in New Zealand while in Australia the B/Yamagata/16/88 lineage was more common. Antigenic and genetic analysis has revealed gradual movement in the both lineages. Careful monitoring of the two virus lineages is important, as they are antigenically distinct. This is an important consideration for influenza vaccine formulation decisions, as only one influenza B component is traditionally included in the annual trivalent influenza vaccine.