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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 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)
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)
Human metapneumovirus (hMPV) is a newly discovered pathogen associated with respiratory tract illness, primarily in young children, immunocompromised individuals, and the elderly. The genomic sequence of the prototype hMPV isolate NL/1/00 without the terminal leader and trailer sequences has been reported previously. Here we describe the leader and trailer(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)
Recently, A/H5N1 influenza viruses were shown to acquire airborne transmissibility between ferrets upon targeted mutagenesis and virus passage. The critical genetic changes in airborne A/Indonesia/5/05 were not yet identified. Here, five substitutions proved to be sufficient to determine this airborne transmission phenotype. Substitutions in PB1 and PB2(More)
Wild waterfowl form the main reservoir of influenza A viruses, from which transmission occurs directly or indirectly to various secondary hosts, including humans. Direct avian-to-human transmission has been observed for viruses of subtypes A(H5N1), A(H7N2), A(H7N3), A(H7N7), A(H9N2) and A(H10N7) upon human exposure to poultry, but a lack of sustained(More)
Repeated transmission of animal influenza viruses to humans has prompted investigation of the viral, host, and environmental factors responsible for transmission via aerosols or respiratory droplets. How do we determine-out of thousands of influenza virus isolates collected in animal surveillance studies each year-which viruses have the potential to become(More)