نتایج جستجو برای: influenza a virus
تعداد نتایج: 13592096 فیلتر نتایج به سال:
In 1999, the World Health Organization switched from annual to semi-annual recommendations for influenza vaccine composition. We compared the antigenic match between recommendations and circulating viruses before and after 1999, in the Northern and Southern Hemispheres. Vaccine match proportion for A/H3N2 viruses increased from 31% to 59% in the Southern Hemisphere (P<0.05), and is now comparab...
conclusions after seven consecutive passages of both cell cultures, the h9n2 virus showed similar antigenicity, also no change on viral titer level and virus replication behavior in adaptation was found. the results highlighted the use of a549 cells for efficient virus isolation. results the influenza virus infectivity was not significant difference in these cells in the presence of trypsin. th...
A remarkable feature of the 2009 pandemic H1N1 influenza virus is its efficient transmissibility in humans compared to that of precursor strains from the triple-reassortant swine influenza virus lineage, which cause only sporadic infections in humans. The viral components essential for this phenotype have not been fully elucidated. In this study, we aimed to determine the viral factors critical...
BACKGROUND Protective antibody immunity against the influenza A virus wanes in 2-7 years due to antigenic drift of the virus' surface proteins. The duration of immune protection is highly variable because antigenic evolution of the virus is irregular. Currently, the variable nature of the duration of immunity has had little attention in analyses of the impact of vaccination, including cost-effe...
the influenza viruses are major etiologic agents of human respiratory infections, and inflict a sizable health and economic burden. this study examines the antiinfluenza virus activity of hydroalcoholic extract of olive leaves (olhe). olive leaves were collected from gardens around the city of shiraz, characterized, dried, ground to powder, and its hydroalcoholic extract was prepared. the influ...
background: the h9n2 subtype of avian influenzaviruses (aivs) has been isolated in multiple avian species inmany european, asian, african and american countries. sincethe first outbreak of h9n2 virus in iran in 1998, this virus haswidely circulated throughout the country, resulting in majoreconomic losses in chicken flocks. several amino acids in thevirus ribonucleoprotein (rnp) complex includi...
the earliest evidences on circulation of avian influenza (ai) virus on the iranian poultry farms date back to 1998. great economic losses through dramatic drop in egg production and high mortality rates are characteristically attributed to h9n2 ai virus. in the present work non-structural (ns) genes of 10 iranian h9n2 chicken ai viruses collected during 1998-2007 were fully sequenced and subjec...
Current vaccines against avian influenza (AI) virus infections are primarily based on classical inactivated whole-virus preparations. Although administration of these vaccines can protect poultry from clinical disease, sterile immunity is not achieved under field conditions, allowing for undetected virus spread and evolution under immune cover. Therefore, there is an urgent need for a robust an...
We firstly report a patient who presented with severe complications after infection with influenza A(H1N1) pdm2009, more than 1 year after recovery from severe H7N9 virus infections. The population of patients who recovered from severe H7N9 infections might be at a higher risk to suffer severe complications after seasonal influenza infections, and they should be included in the high-risk popula...
BACKGROUND Influenza A virus displays strong reassortment characteristics, which enable it to achieve adaptation in human infection. Surveying the reassortment and virulence of novel viruses is important in the prevention and control of an influenza pandemic. Meanwhile, studying the mechanism of reassortment may accelerate the development of anti-influenza strategies. METHODOLOGY/PRINCIPAL FI...
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