Abstract
An outbreak of highly pathogenic avian influenza, caused by a novel reassortant influenza A (H5N8) virus, occurred among poultry and wild birds in South Korea in 2014. The aim of this study was to evaluate the pathogenesis in and mode of transmission of this virus among domestic and wild ducks. Three of the viruses had similar pathogenicity among infected domestic ducks: the H5N8 viruses were moderately pathogenic (0%-20% mortality rate); in wild mallard ducks, the H5N8 and H5N1 viruses did not cause severe illness or death; viral replication and shedding were greater in H5N8-infected mallards than in H5N1-infected mallards. Identification of H5N8 viruses in birds exposed to infected domestic ducks and mallards indicated that the viruses could spread by contact. We propose active surveillance to support prevention of the spread of this virus among wild birds and poultry, especially domestic ducks.
Highlights
Procedure for influenza virus neutralization assayMaterials required Quality Control
The success of virus diagnosis largely depends on the quality of the specimen and the conditions for transport and storage of the specimen before it is processed in the laboratory
Reference antisera to influenza viruses prepared in most animals must be treated with receptor destroying enzyme (RDE) to remove nonspecific inhibitors
Summary
Influenza is caused by a zoonotic virus that occurs in lower animals and birds as well as in humans. Occurring point mutations in the genes coding for the two surface proteins, the HA and the neuraminidase (NA), allow these viruses to escape existing immunity to previously circulating influenza viruses in an individual and in the population Through this process of antigenic drift, new variants evolve, in humans throughout the world, and cause epidemics almost every year. Antigenic drift is less pronounced in avian, swine and equine influenza viruses It does occur, but at a reduced rate, and insufficient knowledge is available to know if immune mechanisms play a role in selection of variants. On the other hand, viruses emerge which contain an HA and/or a NA not present in the previously circulating human influenza viruses Such viruses emerge after direct transmission of viruses from other hosts or after reassortment in a host which is simultaneously infected with two distinct subtypes of influenza virus type A. For the surveillance of respiratory virus disease, in particular for influenza, successful isolation of the virus is crucial for determining its type and subtype, and for further characterization
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