On 11 June 2009, the World Health Organization declared the first human influenza pandemic since 1968–1969. The responsible virus, pandemic (H1N1) 2009 influenza, is a novel triple-reassortant influenza A virus, incorporating avian, swine and human influenza genes.1 The virus is resistant to the anti-influenza medications, amantadine and rimantadine, but is generally sensitive to the neuraminid...

BACKGROUND During the 2009 influenza pandemic, individuals over the age of 60 had the lowest incidence of infection with approximately 25% of these people having pre-existing, cross-reactive antibodies to novel 2009 H1N1 influenza isolates. It was proposed that older people had pre-existing antibodies induced by previous 1918-like virus infection(s) that cross-reacted to novel H1N1 strains. M...

Influenza viruses cause annual epidemics and occasional pandemics that have claimed the lives of millions. The emergence of novel strains continues to challenge the public health and scientific communities. Recent outbreaks of highly pathogenic avian influenza A virus infections (including those of the H5N1 subtype) in poultry and in humans (through contact with infected birds), since 2003, hav...

The spread of influenza has usually been described by a 'density' model, where the largest centres of population drive the epidemic within a country. An alternative model emphasizing the role of air travel has recently been developed. We have examined the relative importance of the two in the context of the 2009 H1N1 influenza epidemic in Scotland. We obtained genome sequences of 70 strains rep...

Since emergence of the pandemic (H1N1) 2009 virus in April 2009, three influenza A viruses-seasonal (H3N2), seasonal (H1N1), and pandemic (H1N1) 2009-have circulated in humans. Genetic reassortment between these viruses could result in enhanced pathogenicity. We compared 4 reassortant viruses with favorable in vitro replication properties with the wild-type pandemic (H1N1) 2009 virus with respe...

Resistance to infection with an influenza A virus conferred by previous infection with an influenza A virus belonging to another subtype is called heterosubtypic immunity. Heterosubtypic immunity is demonstrable in laboratory animals but is believed to be weak in humans. The present study examined whether heterosubtypic immunity from previous influenza virus infection induced resistance to infe...

The emergence of a novel strain of influenza virus A (H1N1) in April 2009 focused attention on influenza surveillance capabilities worldwide. In consultations before the 2009 outbreak of influenza subtype H1N1, the World Health Organization had concluded that the world was unprepared to respond to an influenza pandemic, due in part to inadequate global surveillance and response capacity. We des...

In 2009, a novel swine-origin H1N1 influenza A virus emerged. Here, we characterize the multifunctional NS1 protein of this human pandemic virus in order to understand factors that may contribute to replication efficiency or pathogenicity. Although the 2009 H1N1 virus NS1 protein (2009/NS1) is an effective interferon antagonist, we found that this NS1 (unlike those of previous human-adapted inf...

Abstract : Avian influenza virus (AIV) infection is a major cause of influenza mortality in birds and can cause human mortality and morbidity. Although the risk of infection with avian influenza virus (AIV) is generally low for most people, the pathogenic virus can cross the species barrier and acquires the ability to infect and be transmitted among the human population; therefore the ra...

Tracking novel influenza viruses which have the potential to cause pandemics, such as the pandemic (H1N1) 2009 virus, is a public health priority. Pandemic (H1N1) 2009 virus was first identified in Mexico in April 2009 and spread worldwide over a short period of time. Well-validated diagnostic tools that are rapid, sensitive, and specific for the detection and tracking of this virus are needed....