Genetic characterization of avian influenza viruses isolated in Israel during 2000–2006

Our aim was to establish the phylogenetic and genetic relationships among avian influenza viruses (AIV) recently isolated from poultry in Israel. During this study we analyzed complete nucleotide sequences of two envelope (hemagglutinin and neuraminidase) and six internal genes (polymerase B1, polymerase B2, polymerase A, nucleoprotein, nonstructural, and matrix) of 29 selected H9N2 and six internal genes of five H5N1 viruses isolated in Israel during 2000–2006. Comparative genetic and phylogenetic analyses of these sequences revealed that the local H5N1 viruses are closely related to H5N1 viruses isolated in European, Asian, and Middle Eastern countries in 2005–2006. The H9N2 Israeli isolates, together with viruses isolated in Jordan and Saudi Arabia formed a single group. Our data support the claim that during recent years a new endemic focus of H9N2 has been formed in the Middle East. The introduction of H5N1 and co-circulation of these two subtypes of AIV in this region may augment the risk of potentially pandemic strains emergence.     

Genetic characterization of H5N1 avian influenza viruses isolated in southern China during the 2003–04 avian influenza outbreaks

Summary. The recent H5N1 avian influenza outbreaks in Asia spread over more than 8 countries. It has caused enormous economic loss and grand challenges for the public health. During these breakouts we isolated three strains of H5N1 Avian Influenza Virus (AIV) from chickens and one from duck in different farms of Southern China. We completely sequenced these four AIVs. Molecular characterization demonstrated that these strains retain the reported H5N1 AIV sequence properties relevant to virus virulence and host adaptation. Phylogeny results demonstrated that three of these isolates (except A/Chicken/Guangdong/174/04) were closely linked to other H5N1 AIVs isolated from the recent H5N1 outbreaks in Asia. Six of 8 segments (except PA and M) of A/Chicken/Guangdong/174/04 also shares a close linkage to other H5N1 AIVs isolated from the recent H5N1 outbreaks. However, the PA gene of A/Chicken/Guangdong/174/04 and another H5N1 strain forms a distinct subgroup along with an H6N1 AIV, and the M gene of A/Chicken/Guangdong/174/04 shows a close linkage to some H5N1 AIVs from aquatic species in China. Our findings suggest that a new genotype of AIV (in addition to previous reported ones) was present during the 2003–04 Asian bird flu outbreaks and that continuing virus surveillance of AIVs be conducted to monitor the evolutionary paths of the A/Chicken/Guangdong/174/04-like AIVs.     

Genetic characterization of HA gene of low pathogenic H9N2 influenza viruses isolated in Israel during 2006–2012 periods

H9N2 influenza viruses are isolated in Israel since 2000 and became endemic. From November 2006 to the beginning of 2012, many H9N2 viruses were identified, all belonged to the Asian G1-like lineage represented by A/qu/Hong Kong/G1/97 (H9N2). In the present study, 66 isolates were selected for their hemagglutinin gene characterization. Most H9N2 isolates were distributed between two main groups, identified as the 4th and 5th introductions. The 5th introduction, was represented by a compact cluster containing viruses isolated in 2011–2012; the 4th introduction was subdivided into two subgroups, A and B, each containing at least two clusters, which can be identified as A-1, A-2, B-1, and B2, respectively. Genetic analysis of the deduced HA proteins of viruses, belonging to the 4th and 5th introductions, revealed amino acid variations in 79 out of 542 positions. All isolates had typical low pathogenicity motifs at the hemagglutinin (HA) cleavage site. Most viruses had leucine at position 216 in a receptor binding pocket that enables the virus to bind successfully with the cellular receptors intrinsic to mammals, including humans. It was shown that the differences between the HA proteins of viruses used for vaccine production and local field isolates increased in parallel with the duration and intensity of vaccine use, illustrating the genetic diversity of the H9N2 viruses in Israel.     

Characterization of H5N1 highly pathogenic avian influenza viruses isolated from poultry in Pakistan 2006–2008

Nine avian influenza viruses (AIV), H5N1 subtype, were isolated from dead poultry in the Karachi region of Pakistan from 2006 to 2008. The intravenous pathogenicity indices and HA protein cleavage sites of all nine viruses were consistent with highly pathogenic AIV. Based on phylogenetic analysis of the HA genes, these isolates belong to clade 2.2 and both the HA and NA are closely related to each other (nucleotide identities above 99.0%) and to other Middle Eastern H5N1 AIV isolates (nucleotide identities above 98.0%). The phylogenetic data suggest that the virus in both epornitics of H5N1 HPAIV in commercial poultry in the Karachi region of Pakistan between 2006 and 2008 were from a very closely related source, however, there is inadequate epidemiological data to determine what the reservoir was for the virus between the 2006 and 2007 outbreaks other than that there was a single introduction into the region.     

Genetic characterization of avian-origin H3N2 canine influenza viruses isolated from Guangdong during 2006–2012

Canine influenza virus (CIV) is an emerging pathogen that causes severe and acute respiratory disease in dogs. In 2006, the H3N2 canine influenza virus was first identified in dogs from Guangdong province in China. Up to now, nine CIVs have been isolated from different populations in Guangdong. The nine isolates were grouped together with the canine H3N2 viruses isolated from dogs and felines in Korea, when the eight phylogenetic trees constructed were compared. These findings emphasize the importance of CIV surveillance in this region for understanding the genesis of this virus, and it is important to remain aware of the potential of H3N2 CIV to be transmitted from dogs to the human population.     

Genetic analysis of H9N2 avian influenza viruses circulated in broiler flocks: a case study in Iraq in 2014–2015

H9N2 avian influenza viruses (AIVs) have been recorded in Eurasian for several years. Since 2004–2005, the disease has become endemic in Iraq, causing serious economic losses in the poultry industry. The hemagglutinin (HA) and neuraminidase (NA), two out of eight protein-coding genes, play an important role during the early stage of infection and hinder virus assembling. Little is known about the genetic information of the H9N2 viruses currently circulating in Iraq; thus, gene sequences of six AIVS of the H9N2 subtype have been detected and analyzed in the period of 2014–2015 from different outbreaks of broiler flocks in five provinces situated in the middle and southern parts of Iraq. Genetic comparison of the partial sequences of HA gene indicated that all Iraqi viruses are related to each other and could be divided into two subgroups. Viruses of the first and the second subgroups demonstrated a high similar identity with Pakistani and Iranian viruses, respectively. The nucleotide sequences of the NA protein of the all studied Iraqi viruses were very similar (95.2–100% identity), and shared high nucleotide sequence identity with Iranian, Pakistani, and Lebanese strains. All six recent viruses possessed histidine, alanine, and leucine at positions 183, 190, and 226, respectively, which are the key residues in receptor-binding sites. The Iraqi viruses were closely related to viruses of G1-like lineage isolated from poultry flocks of Iran and Pakistan, suggesting that possible epidemiological links could be derived from a common origin. Further investigations are required and should include the viral isolation and full-length molecular characterization of H9N2 AIVs in this area.     

Emergence of H274Y oseltamivir-resistant A(H1N1) influenza viruses in Japan during the 2008–2009 season

BackgroundA substantial increase in oseltamivir-resistant A(H1N1) influenza viruses was reported in Europe in late 2007.ObjectivesTo monitor the antiviral susceptibility profile of human A(H1N1) influenza viruses in Japan during the 2007–2008 and 2008–2009 seasons.Study designViruses were obtained from respiratory samples of patients with influenza collected in Japan between December 2007 and April 2008 (n = 1046) and between December 2008 and April 2009 (n = 1789). Oseltamivir resistance was determined by an H274Y-specific real-time PCR cycling probe assay and a neuraminidase inhibition assay. Amantadine resistance was assessed by sequencing the M2 gene. Sequencing of the hemagglutinin and NA genes was performed to infer phylogenetic relationships between different strains.ResultsThree of 687 (0.4%) A(H1N1) viruses from the 2007–2008 season and 745 of 745 (100%) viruses from the 2008–2009 season carried the NA–H274Y substitution and demonstrated a >300-fold reduction in oseltamivir susceptibility. All oseltamivir-resistant viruses from the 2008–2009 season possessed an A193T substitution in the receptor-binding domain of the hemagglutinin. Amantadine resistance was detected in 431 of 687 (62.7%) and 0 of 745 (0.0%) of the A(H1N1) viruses from the 2007–2008 and 2008–2009 seasons, respectively.ConclusionsA dramatic surge in oseltamivir-resistant A(H1N1) viruses possessing the NA–H274Y substitution was detected in Japan during the 2008–2009 season. The emergence of oseltamivir-resistant viruses was facilitated by mutations in the viral genome. Intensified surveillance, including phenotypic assays and sequencing of the hemagglutinin, neuraminidase, and M2 gene would allow monitoring of the spread and evolution of drug-resistant influenza virus variants.     

Evolution analysis of the matrix (M) protein genes of 17 H9N2 chicken influenza viruses isolated in northern China during 1998–2008

Matrix (M) protein genes of 17 H9N2 avian influenza viruses (AIVs) isolated from chickens in northern China during the last 10 years were completely sequenced and phylogenetically analyzed. Homology of nucleotide sequences in the M gene of 17 isolates was 92.7–99.9%. Phylogenetic analysis showed that 11 of the tested M genes belong to the A/chicken/HongKong/Y280/97 (Y280)-like lineage, while the other six belong to the A/Quail/HongKong/G1/97 (G1)-like lineage. This is also the first time that a G1-like M gene of a H9N2 virus was detected in chicken flocks in northern China. These newly appearing changes in M genes may be due to reassortment events of AIVs, or they may have come from the H9N2 strains of southern China which surged in northern China after translocation. An analysis of the viral amino acid sequence of M2 protein has revealed substitution of S31N in two isolates, which is the molecular characterization of amantadine resistance in AIVs. Results of this study suggest that long-term monitoring should be continued to track the transmission and evolution of H9N2 AIVs in chickens in China.     

Genetic characterization of swine influenza viruses (H3N2) isolated from Minnesota in 2006–2007

Triple-reassortant (TR) H3N2 swine influenza viruses (SIV) are a major cause of respiratory disease in swine worldwide, causing considerable morbidity and mortality. Continuous surveillance of circulating SIV strains is imperative for effective control and prediction of new emerging strains with interspecies transmission potential. The current study characterized SIV isolates from commercial swine population in USA (2006–2007). Nine isolates were completely sequenced, and the molecular evolution of all gene segments was analyzed. Phylogenetic analysis of the nine H3N2 viruses indicated that these strains belonged to cluster-IV of the human/swine/avian TR genotype, grouping with H3N2 viruses of turkey origin, while forming a separate sub-lineage from those of human and avian origin strains. Ten amino acid changes were observed at the major antigenic sites of HA1 region compared to the cluster-III reference strain, with differences in glycosylation sites. All the nine strains were antigenically related to the cluster-IV turkey strain than the cluster-III reference strain. The results of this study suggest that contemporary TR H3N2 strains circulating in North America share the same genetic constellation, thus maintaining the gene pool without any further event of genetic reassortment unlike swine-origin pandemic strain A/California/04/2009/H1N1. These findings strongly support the need for continuous surveillance and monitoring of genetic changes in SIV, to identify evolving strains that might pose a threat to human or animal health.     

Epidemiology of pandemic influenza A/H1N1 virus during 2009–2010 in Taiwan

Outbreak of swine-origin influenza A/H1N1 virus (pdmH1N1) occurred in 2009. Taiwanese authorities implemented nationwide vaccinations with pdmH1N1-specific inactivated vaccine as of November 2009. This study evaluates prevalence, HA phylogenetic relationship, and transmission dynamic of influenza A and B viruses in Taiwan in 2009–2010. Respiratory tract specimens were analyzed for influenza A and B viruses. The pdmH1N1 peaked in November 2009, was predominant from August 2009 to January 2010, then sharply dropped in February 2010. Significant prevalence peaks of influenza B in April–June of 2010 and H3N2 virus in July and August were observed. Highest percentage of pdmH1N1- and H3N2-positive cases appeared among 11–15-year-olds; influenza B-positive cases were dominant among those 6–10 years old. Maximum likelihood phylogenetic trees showed 11 unique clusters of pdmH1N1, seasonal H3N2 influenza A and B viruses, as well as transmission clusters and mixed infections of influenza strains in Taiwan. The 2009 pdmH1N1 virus was predominant in Taiwan from August 2009 to January 2010; seasonal H3N2 influenza A and B viruses exhibited small prevalence peaks after nationwide vaccinations. Phylogenetic evidence indicated transmission clusters and multiple independent clades of co-circulating influenza A and B strains in Taiwan.     

Genetic analysis of H3 subtype influenza viruses isolated from domestic ducks in northern China during 2004–2005

The broad distribution and prevalence of H3 subtype influenza viruses in avian and mammalian hosts constitutes a global threat to both human and veterinary health. In this present study, six H3N8 influenza viruses isolated from domestic ducks during 2004–2005 in northern China were genetically and phylogenetically characterized. Sequence analysis showed that HA, NA, and M genes of all the six H3N8 isolates had a close relationship with those of Equine/Jilin/1/89 (H3N8) virus, which once caused outbreak in equine populations in northern China. The PB2 and PA genes of the viruses possessed the highest similarities with highly pathogenic avian H5N1 influenza viruses currently circulating in this region. These findings emphasize the importance of avian influenza virus surveillance in this region for understanding the genesis and emergency of novel reassortants with pandemic potential.     

Molecular evolution of the hemagglutinin and neuraminidase genes of pandemic (H1N1) 2009 influenza viruses in Sendai, Japan, during 2009–2011

Analyzing the evolutionary pattern of the influenza A(H1N1)pdm09 strain in different regions is important for understanding its diversification. We therefore conducted this study to elucidate the genetic variability and molecular evolution of the influenza A(H1N1)pdm09 strains that circulated during the 2009–2010 and 2010–2011 influenza seasons in Sendai, Japan. Nasopharyngeal swab specimens were collected from patients with influenza-like illnesses who visited outpatient clinics in Sendai City, Japan, from September 2009 to April 2011. A total of 75 isolates were selected from September 2009 to April 2011 to analyze the genetic changes in the entire hemagglutinin 1 (HA1) segment of the HA gene and the neuraminidase (NA) gene based on sequence analysis. Bayesian coalescent Markov chain Monte Carlo analyses of HA1 and NA gene sequences were performed for further analysis. High sequence identities were observed for HA1 and NA in influenza A(H1N1)pdm09, displaying 99.06 and 99.33 % nucleotide identities, respectively, with the A(H1N1)pdm09 vaccine strain A/California/07/2009. The substitution rates of nucleotides for HA1 in the 2009–2010 and 2010–2011 were 1.5 × 10^?3 and 1.6 × 10^?3 substitutions per site per year, respectively. Phylogenetic tree analysis demonstrated that Sendai isolates were clustered into global clade 7, which is characterized by an S203T mutation in the HA1 gene. Moreover, two distinct circulation clusters were present in the 2010–2011 season. Mutations were present in antigenic or receptor-binding domains of the HA1 segment, including A141V, S143G, S183P, S185T, and S203T. The Bayesian skyline plot model illustrated a steady rate for the maintenance of genetic diversity, followed by a slight increase in the later part of the 2010–2011 season. Selection analysis revealed that the HA1 (position 197) and NA (position 46) sites were under positive selection; however, no known mutation conferring resistance to NA inhibitors such as H275Y was observed. The effect on control of the influenza A(H1N1)pdm09 virus, including vaccine strain selection, requires continuous monitoring of the strain by genetic surveillance.     

Phylogenetic analysis of the S1 glycoprotein gene of infectious bronchitis viruses isolated in China during 2009–2010

As part of our ongoing surveillance program, 40 field strains of avian infectious bronchitis virus (IBV) were isolated from dead or diseased chicken flocks in different areas of China between 2009 and 2010. S1 glycoprotein genes of these strains were sequenced and analyzed with 38 strains published in GenBank. S1 genes of these isolated strains and the vaccine strains showed nucleotide homologies ranging from 65.2 to 82% and amino acid homologies ranging from 58.4 to 81.9%. Meanwhile, Chinese IBV strains isolated in this study, which were mainly nephropathogenic, could be separated into six variant lineages (CH I–CH VI), and current vaccine strains used in China formed Mass variant lineage that is evolutionarily distant from Chinese isolates. Moreover, CK/CH/GD/NC10, CK/CH/GD/KP10, and our previous isolates TC07-2 formed the CH VI lineage, showing larger evolutionary distances from other strains. Taken together, these findings suggested that various variant lineages were co-circulating in China now, and appeared to be continuously evolving, alternative indigenous vaccines indeed need for effective control of IB in China.     

Characterization of a reassortant H11N9 subtype avian influenza virus isolated from bean goose along the East Asian–Australian flyway

During the surveillance of avian influenza viruses in the Dongxi Lake wetland of Hubei in 2015–2016, an H11N9 avian influenza virus was isolated from a bean goose (Anser fabalis). Phylogenetic analysis showed that the HA gene of this isolate belongs to the North American lineage; however, the NA and the internal genes of the isolate were generated from the Eurasian lineage. This strain had reduced pathogenicity in mice and was capable of replication in the mouse lung without prior adaptation. This is the first report detecting H11N9 subtype influenza virus from migratory birds in central China. These findings highlight the transmission of avian influenza virus along the East Asian–Australian flyway and the need for continuing surveillance in central China.     

Analysis of S1 gene of avian infectious bronchitis virus isolated in southern China during 2011–2012

Sixty-two strains of avian infectious bronchitis virus (IBV) were isolated from diseased chickens at different farms in southern China during 2011–2012, and 66.1 % of the isolated strains were associated with typical nephritis. Analysis of the S1 gene sequences amplified from the 62 isolated strains together with 40 reference strains published in Genbank showed nucleotide homologies ranging from 63.5 to 99.9 % and amino acid homologies ranging from 57.9 to 100 %. Phylogenetic analysis revealed that all Chinese IBV strains were clustered into six distinct genetic groups (I–VI). Most of the isolated strains belonged to group I, and the isolation of group V strains was increased compared with an earlier period of surveillance. Current vaccine strains used in China (H120, H52, W93, and Ma5) formed the group Mass which is evolutionarily distant from Chinese isolates. Alignment of S1 amino acid sequences revealed polymorphic and diverse substitutions, insertions, and deletions, and the S1 protein of major pandemic strains contained 540 amino acids with a cleavage site sequence of HRRRR or RRF(L/S)RR. Further analysis showed that recombination events formed a new subgroup. Taken together, these findings suggest that various IBV variants were co-circulating and undergoing genetic evolution in southern China during the observation period. Therefore, long-term continuing surveillance is significantly important for prevention and control of IBV infection.     

Full-length characterization and phylogenetic analysis of hemagglutinin gene of H9N2 virus isolated from broilers in Iran during 1998–2007

H9N2 avian influenza A viruses (AIV) have become panzootic in Eurasia over the last decade and are endemic in Iran since 1998, and inactivated vaccine has been used in chickens to control the disease. The hemagglutinin (HA), one of eight protein-coding genes, plays an important role during the early stage of infection. To study their evolution and zoonotic potential, we conducted an in silico analysis of H9N2 viruses that have infected broiler in Tehran Province, Iran between 1998 and 2007. The complete coding region of HA genes from nine H9N2 subtypes isolated from chicken flocks in Tehran Province during 1998–2007 was amplified and sequenced. Sequence analysis and phylogenetic studies of H9N2 subtype viruses on the basis of data of 9 viruses in this study and 30 selected strains are available in the GenBank. Sequence and phylogenetic analyses revealed a large number of similar substitution mutations and close evolutionary relation among sequences of HA. The isolates possessed two types of amino acid motif –R–S-S-R/G-L- and -R-S-N-R/G-L- at the cleavage site of HA. The results showed that all nine representative H9N2 isolates belong to low pathogenic AIVs since none of the amino acid sequences at the cleavage site of the HA of the isolates possessed the basic motif required for highly pathogenic viruses (R-X-R/K-R). Six out of these nine isolates possessed leucine at position 226, which prevails in the sequences found in human strains. Phylogenetic analysis showed that all our isolates belonged to the G1-like sublineage. Also, these isolates showed some degree of homology with other H9N2 isolates, e.g., 89.46–93.93.39% with qu/HK/G1/97 and 93.39–98.39% with pa/Narita/92A/98. The available evidence indicates that HA genes of H9 influenza virus circulating in Iran during the past years were not well conserved. Our finding emphasizes the importance of reinforcing AIV surveillance, especially after the emergence of high pathogenicity in poultry in Iran.     

Molecular evolution of influenza A/H3N2 viruses in the province of Québec (Canada) during the 1997-2000 period.

In this study, we compared antigenic (hemagglutination inhibition (HI) assay) and molecular (sequencing of the hemagglutinin (HA1) gene) characterization of influenza isolates collected in the Province of Québec (Canada) during the last three flu seasons (1997-2000). Twenty-three isolates were tested by a standard HI assay and 37 by sequencing of the HA1 gene for their homology to the A/H3N2 vaccine strains A/Wuhan/359/95 (1997-1998) and A/Sydney/5/97 (1998-1999 and 1999-2000). By HI, two isolates were antigenically similar to A/Wuhan/359/95 (both from 1997 to 1998), 16 were similar to A/Sydney/5/97 (1997-2000) and no conclusions could be inferred for the other five isolates due to identical HI titers for the two vaccine strains (n=4) or insufficient viral titer (n=1). Sequence analysis revealed that four isolates from 1997 to 1998 were related to A/Wuhan/359/95 whereas the others (n=4) from 1997 to 1998, as well as all isolates from 1998 to 1999 (n=18) and 1999 to 2000 (n=11) were closer to A/Sydney/5/97. The mean number of amino acid differences for the 33 A/Sydney/5/97-like isolates compared with the homologous vaccine strain was 6.3 (1.9%), 9.2 (2.8%) and 13.6 (4.1%) for those collected in 1997-1998, 1998-1999, and 1999-2000, respectively. Phylogenetic analysis confirmed that a progressive drift occurred among our A/H3N2 influenza isolates over the last three flu seasons. Furthermore, it revealed that isolates collected during the last two flu seasons were in fact more related to A/Panama/2007/99 (2000-2001 vaccine strain) than to A/Sydney/5/97. Our studies suggest that molecular analysis of the HA1 gene should complement the HI assay for a more accurate analysis of influenza A virus drift.     

Surveillance and characterization of avian influenza viruses from migratory water birds in eastern Hokkaido, the northern part of Japan, 2009–2010

Avian influenza virus (AIV) surveillance was conducted around a small pond in Obihiro, eastern Hokkaido, Japan. Eleven AIVs were isolated from a total of 1,269 fecal samples of migratory wild birds collected during 2009 and 2010. The sample number covered approximately 60 % of the total number of birds observed during sampling periods. The subtypes of the isolates included H3N8 (4 isolates), H5N2 (3), H6N2 (2), H6N1 (1), and H11N2 (1). The H3N8 subtype was most prevalent as in the previous studies performed in Hokkaido. The three H5N2 isolates genetically characterized as low pathogenic AIV were closely related to the strains previously isolated from aquatic wild birds in Japan and also to the Korean strains isolated from aquatic birds in recent years. In Korea, H5N2 subtype virus has often been isolated from poultry and wild birds, as well as reassortant viruses generated from duck H5N2 viruses and chicken H9N2 virus, and avian-swine-like reassortant H5N2 viruses. Considering the previous chicken outbreaks caused by highly pathogenic H5N2 viruses, which affected many countries, it should be an important priority to continue, monitoring the evolution of H5N2 viruses circulating in the region.     

An aptamer that binds efficiently to the hemagglutinins of highly pathogenic avian influenza viruses (H5N1 and H7N7) and inhibits hemagglutinin–glycan interactions

Highly pathogenic avian influenza (HPAI) H5 and H7 viruses have ravaged the poultry industry in numerous countries in Asia, Europe, Africa and the Middle East, and have resulted in the deaths of millions of birds. Although HPAI H5N1 viruses currently remain avian viruses, they are continuously evolving and have the potential to become pandemic-type viruses capable of human–human transmission. To develop specific reagents to allow better preparedness against this threat, we selected an aptamer (8-3) from a completely random RNA pool that binds with high affinity (∼K_D 170 pM) to the hemagglutinins (HAs) derived from HPAI H5N1 (A/H5N1/Vietnam/1194/2004 and A/H5N1/Indonesia/05/2005) and H7N7 (A/H7N7/Netherlands/219/2003) influenza A viruses. Aptamer 8-3 was able to efficiently distinguish HAs derived from subtypes of influenza A virus other than H5 and H7. Aptamer 8-3 was analyzed further to assess its ability to interfere with HA–glycan interactions using our previously established SPR-based competitive assay, and we found that aptamer 8-3 efficiently interferes with HA–glycan binding (EC₅₀ ∼ 25 nM). To derive shorter variants for other applications, aptamer 8-3 was shortened to a 44-mer by deletion analyses. The shortened aptamer, 8-3S, retains the full-length aptamer’s affinity and specificity for its cognate Has, and also interferes with HA–glycan interactions. These studies suggest that aptamer 8-3S should be studied further to explore its potential applications not only in surveillance and diagnosis, but also in the development of H5N1- and H7N7-specific virucidal products that interfere with virus–host interactions to contain future H5N1 and H7N7 pandemics.