The transmission of avian H5N1 influenza viruses to 18 humans in Hong Kong in 1997 with six deaths established that avian influenza viruses can transmit to and cause lethal infection in humans. This report characterizes the antigenic and biological properties of the H5N1 influenza viruses isolated from chickens, ducks, and geese from farms and poultry markets in Hong Kong during 1997 and compares them with those of virus isolated from the index human case. Each of the H5N1 viruses from Hong Kong poultry markets that were tested were lethal in chickens, possessed polybasic amino acids at the carboxy-terminus of HA1, and by definition were highly pathogenic in poultry. The available nonpathogenic H5 influenza viruses and the pathogenic H5N1 virus from Hong Kong were analyzed with monoclonal antibodies prepared to A/chicken/Pennsylvania/1370/83 (H5N2). The analysis revealed limited antigenic drift in 15 years and established that monoclonal antibodies are useful reagents for identification and antigenic analysis of avian strains that may transmit to humans in the future. One of the monoclonal antibodies permitted separation of the H5N1 influenza viruses from poultry into two groups that correlated with the presence or absence of a carbohydrate at residue 158 adjacent to the receptor binding site on HA. The H5N1 viruses examined replicated in geese, pigs, rats, and mice, but to only a very limited extent in ducks. It is noteworthy that all infected geese shed virus and that the H5N1 viruses caused disease signs and death in a portion (3 of 16) of the geese, with evidence of systemic spread to the brain. The tropism for geese is unusual and may provide insight into the origin of these viruses. In mice, the H5N1 virus caused lethal pneumonia and spread systemically to the brain. Mice would thus provide an ideal model system for studying immune responses and pathogenesis. Transmission experiments in chickens revealed that the H5N1 viruses are spread by fecal-oral transmission rather than by aerosol, and that the viruses are inactivated by drying of feces at ambient temperature. However, infectivity is maintained for at least 4 days in wet feces at 25 degreesC. There were differences in the morphology of the H5N1 viruses isolated from birds and humans. The perpetuation of H5N1 influenza viruses in the poultry markets in Hong Kong and the transmission of these viruses to humans emphasize the importance of these markets in the epidemiology of influenza. The poultry markets are of critical importance in the perpetuation and transmission of influenza viruses to other avian species and to mammals, including humans.
Influenza A Virus, H5N1 SubtypeAnimalsAntibodies, MonoclonalChick EmbryoChickensDucksFecesGeeseHong KongHumansInfluenza A virusInfluenza in BirdsMicePoultry DiseasesRatsTurkeysVirus ReplicationZoonoses
Structured evidence records
Evidence records
13 total
Host Range Experiment4 records
Host Range ExperimentExtraction confidence 0.90
Key finding
Avian H5N1 influenza viruses from Hong Kong poultry replicated efficiently in geese, causing disease and systemic infection, and also infected pigs, rats, and mice, while replication was limited in ducks.
The H5N1 viruses examined replicated in geese, pigs, rats, and mice, but to only a very limited extent in ducks. It is noteworthy that all infected geese shed virus and that the H5N1 viruses caused disease signs and death in a portion (3 of 16) of the geese, with evidence of systemic spread to the brain.
Method
experimental infection; virus replication assay
Sample type
brain
Experimental system
in vivo animal experiment
Host Range ExperimentExtraction confidence 0.90
Key finding
H5N1 influenza viruses from Hong Kong poultry caused lethal pneumonia and systemic infection in mice.
In mice, the H5N1 virus caused lethal pneumonia and spread systemically to the brain. Mice would thus provide an ideal model system for studying immune responses and pathogenesis.
Method
experimental infection; pathogenesis assay
Sample type
lung; brain
Experimental system
in vivo animal experiment
Host Range ExperimentExtraction confidence 0.90
Key finding
Experimental infections in chickens showed fecal-oral transmission of H5N1 influenza virus and loss of infectivity in dried feces.
Transmission experiments in chickens revealed that the H5N1 viruses are spread by fecal-oral transmission rather than by aerosol, and that the viruses are inactivated by drying of feces at ambient temperature.
Method
transmission experiment
Sample type
feces
Experimental system
in vivo animal experiment
Host Range ExperimentExtraction confidence 0.90
Key finding
H5N1 influenza viruses replicated to a limited extent in ducks, indicating reduced susceptibility.
The H5N1 viruses examined replicated in geese, pigs, rats, and mice, but to only a very limited extent in ducks.
Method
experimental infection
Experimental system
in vivo animal experiment
Zoonotic Surveillance3 records
Zoonotic SurveillanceExtraction confidence 0.80
Key finding
Avian H5N1 influenza viruses were isolated and characterized from chickens, ducks, and geese in Hong Kong poultry farms and markets as part of monitoring of avian hosts linked to human cases.
This report characterizes the antigenic and biological properties of the H5N1 influenza viruses isolated from chickens, ducks, and geese from farms and poultry markets in Hong Kong during 1997 and compares them with those of virus isolated from the index human case.
Method
virus isolation; antigenic characterization
Geographic raw
Hong Kong
Country inferred
China
Zoonotic SurveillanceExtraction confidence 0.80
Key finding
Avian H5N1 influenza viruses were isolated and characterized from ducks in Hong Kong markets and farms as part of zoonotic viral monitoring.
This report characterizes the antigenic and biological properties of the H5N1 influenza viruses isolated from chickens, ducks, and geese from farms and poultry markets in Hong Kong during 1997 and compares them with those of virus isolated from the index human case.
Method
virus isolation; antigenic characterization
Geographic raw
Hong Kong
Country inferred
China
Zoonotic SurveillanceExtraction confidence 0.80
Key finding
Avian H5N1 influenza viruses were isolated and characterized from geese in Hong Kong farms and markets, representing surveillance of avian hosts associated with zoonotic influenza.
This report characterizes the antigenic and biological properties of the H5N1 influenza viruses isolated from chickens, ducks, and geese from farms and poultry markets in Hong Kong during 1997 and compares them with those of virus isolated from the index human case.
Method
virus isolation; antigenic characterization
Geographic raw
Hong Kong
Country inferred
China
Molecular Adaptation2 records
Molecular AdaptationExtraction confidence 0.90
Key finding
H5N1 viruses from Hong Kong poultry possessed polybasic amino acids at the HA1 cleavage site conferring high pathogenicity in chickens.
Each of the H5N1 viruses from Hong Kong poultry markets that were tested were lethal in chickens, possessed polybasic amino acids at the carboxy-terminus of HA1, and by definition were highly pathogenic in poultry.
Genes or proteins
HA1
Mechanism types
pathogenicity; host_adaptation
Molecular AdaptationExtraction confidence 0.85
Key finding
H5N1 poultry viruses differed by the presence or absence of a carbohydrate at HA residue 158 near the receptor binding site, indicating antigenic variation affecting receptor binding properties.
One of the monoclonal antibodies permitted separation of the H5N1 influenza viruses from poultry into two groups that correlated with the presence or absence of a carbohydrate at residue 158 adjacent to the receptor binding site on HA.
Genes or proteins
HA
Mechanism types
receptor_binding; antigenic_variation
Spillover Event2 records
Spillover EventExtraction confidence 0.99
Key finding
Avian H5N1 influenza viruses transmitted from poultry to humans in Hong Kong in 1997 and caused lethal human infections.
The transmission of avian H5N1 influenza viruses to 18 humans in Hong Kong in 1997 with six deaths established that avian influenza viruses can transmit to and cause lethal infection in humans.
Study design
outbreak investigation
Transmission direction
animal-to-human
Geographic raw
Hong Kong
Country inferred
China
Spillover EventExtraction confidence 0.96
Key finding
H5N1 influenza viruses circulating in poultry markets in Hong Kong were transmitted to humans.
The perpetuation of H5N1 influenza viruses in the poultry markets in Hong Kong and the transmission of these viruses to humans emphasize the importance of these markets in the epidemiology of influenza.
Study design
field surveillance
Transmission direction
animal-to-human
Geographic raw
Hong Kong
Country inferred
China
Genomic Evolution1 records
Genomic EvolutionExtraction confidence 0.75
Key finding
H5N1 viruses from Hong Kong poultry possessed polybasic amino acids at HA1 C-terminus and could be divided into two groups differing by a glycosylation site at residue 158 near the receptor binding site, evidencing molecular evolution in the HA gene.
Each of the H5N1 viruses from Hong Kong poultry markets that were tested were lethal in chickens, possessed polybasic amino acids at the carboxy-terminus of HA1, and by definition were highly pathogenic in poultry. One of the monoclonal antibodies permitted separation of the H5N1 influenza viruses from poultry into two groups that correlated with the presence or absence of a carbohydrate at residue 158 adjacent to the receptor binding site on HA.
Genes or proteins
HA; HA1
Analysis methods
antigenic analysis; molecular characterization
Receptor Usage1 records
Receptor UsageExtraction confidence 0.80
Key finding
H5N1 influenza viruses from poultry in Hong Kong differed in the glycosylation status at residue 158 near the HA receptor binding site, defining two antigenic groups linked to receptor-binding region structure.
One of the monoclonal antibodies permitted separation of the H5N1 influenza viruses from poultry into two groups that correlated with the presence or absence of a carbohydrate at residue 158 adjacent to the receptor binding site on HA.
