Sander Herfst

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The recently raised awareness of the threat of a new influenza pandemic has stimulated interest in the detection of influenza A viruses in human as well as animal secretions. Virus isolation alone is unsatisfactory for this purpose because of its inherent limited sensitivity and the lack of host cells that are universally permissive to all influenza A(More)
In wild aquatic birds and poultry around the world, influenza A viruses carrying 15 antigenic subtypes of hemagglutinin (HA) and 9 antigenic subtypes of neuraminidase (NA) have been described. Here we describe a previously unidentified antigenic subtype of HA (H16), detected in viruses circulating in black-headed gulls in Sweden. In agreement with(More)
Highly pathogenic avian influenza A/H5N1 virus can cause morbidity and mortality in humans but thus far has not acquired the ability to be transmitted by aerosol or respiratory droplet ("airborne transmission") between humans. To address the concern that the virus could acquire this ability under natural conditions, we genetically modified A/H5N1 virus by(More)
The swine-origin A(H1N1) influenza virus that has emerged in humans in early 2009 has raised concerns about pandemic developments. In a ferret pathogenesis and transmission model, the 2009 A(H1N1) influenza virus was found to be more pathogenic than a seasonal A(H1N1) virus, with more extensive virus replication occurring in the respiratory tract.(More)
Human metapneumovirus (HMPV) is a member of the subfamily Pneumovirinae within the family Paramyxo- viridae. Other members of this subfamily, respiratory syncytial virus and avian pneumovirus, can be divided into subgroups on the basis of genetic or antigenic differences or both. For HMPV, the existence of different genetic lineages has been described on(More)
Avian A/H5N1 influenza viruses pose a pandemic threat. As few as five amino acid substitutions, or four with reassortment, might be sufficient for mammal-to-mammal transmission through respiratory droplets. From surveillance data, we found that two of these substitutions are common in A/H5N1 viruses, and thus, some viruses might require only three(More)
The clinical impact of the 2009 pandemic influenza A(H1N1) virus (pdmH1N1) has been relatively low. However, amino acid substitution D222G in the hemagglutinin of pdmH1N1 has been associated with cases of severe disease and fatalities. D222G was introduced in a prototype pdmH1N1 by reverse genetics, and the effect on virus receptor binding, replication,(More)
In the first 6 months of the H1N1 swine-origin influenza virus (S-OIV) pandemic, the vast majority of infections were relatively mild. It has been postulated that mutations in the viral genome could result in more virulent viruses, leading to a more severe pandemic. Mutations E627K and D701N in the PB2 protein have previously been identified as determinants(More)
Membrane fusion promoted by human metapneumovirus (HMPV) fusion (F) protein was suggested to require low pH (R. M. Schowalter, S. E. Smith, and R. E. Dutch, J. Virol. 80:10931-10941, 2006). Using prototype F proteins representing the four HMPV genetic lineages, we detected low-pH-dependent fusion only with some lineage A proteins and not with lineage B(More)
Using reverse transcription/polymerase chain reaction (RT-PCR), we have screened more than 8500 wild birds in Northern Europe in 1999 and 2000 for the presence of influenza A virus. Although our primary focus was on ducks, geese, and shorebirds, we have also tested thousands of samples from other bird species. Approximately 1% of our samples were positive(More)