Background:To monitor carrier hosts of avian influenza in Nigeria,we randomly collected cloaca swab specimens from 155 ducks at a live bird market(LBM)in Ibadan,southwest Nigeria,between July 2011 and July 2012.Method...Background:To monitor carrier hosts of avian influenza in Nigeria,we randomly collected cloaca swab specimens from 155 ducks at a live bird market(LBM)in Ibadan,southwest Nigeria,between July 2011 and July 2012.Methods:The samples were analyzed by real-time reverse transcription-polymerase chain reaction(RT-PCR)and virus isolation was carried out in embryonated chicken eggs.Partial sequencing of the antigenic cleavage site of the haemagglutinin(HA)gene was performed,multiple sequence alignment was carried out using ClustalW,and a phylogenetic tree was constructed using the neighbor joining method.Results:Twenty(13%)of the 155 samples were positive for avian influenza subtype H5N2 by real-time RT-PCR and three isolates were obtained from embryonated chicken eggs.Partial sequencing of the amino acid cleavage site of the HA genes of two isolates corresponded to a PQRETGL*F sequence that is common in low pathogenic avian influenza(LPAI).Phylogenetically,the HA genes of the two influenza viruses are monophyletic and clustered with H5N2 viruses detected in wild ducks from Africa.Conclusion:The occurrence of LPAI in domestic ducks in Nigeria underscores the importance of continuous surveillance and monitoring of the virus(in a country that is considered to be free of avian influenza)in order to prevent the emergence of virulent strains that may spread to commercial poultry and humans.展开更多
Objective Both the 2, 6 linkage and its topology on target cells are critical for the recognition by human influenza virus. The binding preference of avian flu virus H5N1 HA to the 2, 3-1inked sialylated glycans is co...Objective Both the 2, 6 linkage and its topology on target cells are critical for the recognition by human influenza virus. The binding preference of avian flu virus H5N1 HA to the 2, 3-1inked sialylated glycans is considered the major factor limiting its efficient infection and transmission in humans. To monitor potential adaptation of H5N1 virus in human population, the surveillance of receptor-binding specificity was undertaken in China. Methods The binding specificity of 32 human H5N1 virus strains isolated from 2003 to 2009 was tested by 2, 3-specific sialidase-treated chicken red blood cell （CRBC） agglutination assay and a solid-phase direct binding assay with synthetic sialylglycopolymers. Results Dual binding preference to 2, 3 and 2, 6-glycans were found in two strains： A/Guangdong/1/06 （A/GD/1/06） and A/Guangxi/1/08 （A/GX/1/08）. Though minor effect of short-2, 6-binding was detected in A/GX/1/08 at a low virus titer, both showed high affinity to the oligosaccharide at a high load. Notably both are of the long-2, 6-recognition, with the same topology as that of human H1N1 and H3N2 viruses. Conclusion The findings suggest that human H5N1 virus in China likely acquired the potential human-adaptation ability. Further research and surveillance on receptor-binding specificity of H5N1 viruses are required.展开更多
Influenza type A, is an avian disease with a complicated ecology and transmission routes in verity of avian and mammalian species. The present study aimed to demonstrate the characteristic, clinical and experimental f...Influenza type A, is an avian disease with a complicated ecology and transmission routes in verity of avian and mammalian species. The present study aimed to demonstrate the characteristic, clinical and experimental features as well as pathogenecity of Avian Influenza Virus H5N2 through a laboratory-based experiment in western Iran. A post-mortem examination of experimentally chickens was undertaken in 2007. Overall 25 local native chickens including 15 layers and 10 roosters suspected with AI infection as well as 50 experimental chickens were studied. The virus was isolated from the embryonated specific pathogen-free （SPF） chicken eggs. There was an embryo mortality rate of 71% within 48 hours post inoculation （PI）. Hemagglutinin （HA） inhibition titres against AIV subtype H5N2 in the layers ranged from 4.20 to 4.75 （acute） and 6.21 to 7.82 （convalescent）. Accumulated mucous in trachea of the dissected birds, congested lungs, atrophied bursa, haemorrhagic cecal tonsils and inflamed thymus were the main clinical symptoms. Thickened and infected air sacs, pre hepatitis and enteritis signs were also observed, in experimental birds, the eyes＇ colour became red and the eyelashes were almost double in diameters after being infected. The AI virus found in the present study was classified as a highly pathogenic avian influenza.展开更多
文摘Background:To monitor carrier hosts of avian influenza in Nigeria,we randomly collected cloaca swab specimens from 155 ducks at a live bird market(LBM)in Ibadan,southwest Nigeria,between July 2011 and July 2012.Methods:The samples were analyzed by real-time reverse transcription-polymerase chain reaction(RT-PCR)and virus isolation was carried out in embryonated chicken eggs.Partial sequencing of the antigenic cleavage site of the haemagglutinin(HA)gene was performed,multiple sequence alignment was carried out using ClustalW,and a phylogenetic tree was constructed using the neighbor joining method.Results:Twenty(13%)of the 155 samples were positive for avian influenza subtype H5N2 by real-time RT-PCR and three isolates were obtained from embryonated chicken eggs.Partial sequencing of the amino acid cleavage site of the HA genes of two isolates corresponded to a PQRETGL*F sequence that is common in low pathogenic avian influenza(LPAI).Phylogenetically,the HA genes of the two influenza viruses are monophyletic and clustered with H5N2 viruses detected in wild ducks from Africa.Conclusion:The occurrence of LPAI in domestic ducks in Nigeria underscores the importance of continuous surveillance and monitoring of the virus(in a country that is considered to be free of avian influenza)in order to prevent the emergence of virulent strains that may spread to commercial poultry and humans.
基金supported by the Ministry of Science and Technology (project No.2007AA02Z417)
文摘Objective Both the 2, 6 linkage and its topology on target cells are critical for the recognition by human influenza virus. The binding preference of avian flu virus H5N1 HA to the 2, 3-1inked sialylated glycans is considered the major factor limiting its efficient infection and transmission in humans. To monitor potential adaptation of H5N1 virus in human population, the surveillance of receptor-binding specificity was undertaken in China. Methods The binding specificity of 32 human H5N1 virus strains isolated from 2003 to 2009 was tested by 2, 3-specific sialidase-treated chicken red blood cell （CRBC） agglutination assay and a solid-phase direct binding assay with synthetic sialylglycopolymers. Results Dual binding preference to 2, 3 and 2, 6-glycans were found in two strains： A/Guangdong/1/06 （A/GD/1/06） and A/Guangxi/1/08 （A/GX/1/08）. Though minor effect of short-2, 6-binding was detected in A/GX/1/08 at a low virus titer, both showed high affinity to the oligosaccharide at a high load. Notably both are of the long-2, 6-recognition, with the same topology as that of human H1N1 and H3N2 viruses. Conclusion The findings suggest that human H5N1 virus in China likely acquired the potential human-adaptation ability. Further research and surveillance on receptor-binding specificity of H5N1 viruses are required.
文摘Influenza type A, is an avian disease with a complicated ecology and transmission routes in verity of avian and mammalian species. The present study aimed to demonstrate the characteristic, clinical and experimental features as well as pathogenecity of Avian Influenza Virus H5N2 through a laboratory-based experiment in western Iran. A post-mortem examination of experimentally chickens was undertaken in 2007. Overall 25 local native chickens including 15 layers and 10 roosters suspected with AI infection as well as 50 experimental chickens were studied. The virus was isolated from the embryonated specific pathogen-free （SPF） chicken eggs. There was an embryo mortality rate of 71% within 48 hours post inoculation （PI）. Hemagglutinin （HA） inhibition titres against AIV subtype H5N2 in the layers ranged from 4.20 to 4.75 （acute） and 6.21 to 7.82 （convalescent）. Accumulated mucous in trachea of the dissected birds, congested lungs, atrophied bursa, haemorrhagic cecal tonsils and inflamed thymus were the main clinical symptoms. Thickened and infected air sacs, pre hepatitis and enteritis signs were also observed, in experimental birds, the eyes＇ colour became red and the eyelashes were almost double in diameters after being infected. The AI virus found in the present study was classified as a highly pathogenic avian influenza.
