Avian Influenza A(H9N2) Virus in Poultry Worker, Pakistan, 2015

H9N2 influenza A viruses found to be enzootic in Punjab Pakistan's bird markets with evidence of human H9N2 nasal colonization

OBJECTIVES

This study sought to detect and characterize influenza A (IAV) and influenza D (IDV) viruses circulating among commercial birds and shop owners in Pakistan's live bird markets.

METHODS

Oropharyngeal swabs (n = 600; n = 300 pools) collected from poultry and nasopharyngeal swabs (n = 240) collected from poultry workers were studied for molecular evidence of IAV and IDV using real-time and conventional real-time reverse transcription polymerase chain reaction protocols.

RESULTS

Nineteen (6.3%) poultry pools were positive for IAV and 73.9% of these were positive for H9N2 subtypes. Two (0.83%) poultry workers had evidence of IAV, and both were also H9N2 subtypes. The poultry and human IAV-positive specimens all clustered phylogenetically by Sanger and next-generation sequencing with previously detected H9N2 poultry isolates. No field specimens were positive for IDV.

CONCLUSION

H9N2 IAV is likely enzootic in Punjab Province Pakistan's live bird markets and may be colonizing the noses of workers and market visitors. Regular monitoring for avian influenza-associated human illness in Punjab seems to be a needed public measure.

Mapping Genetic Markers Associated with Antigenicity and Host Range in H9N2 Influenza A Viruses Infecting Poultry in Pakistan

The aim of the current study was to map the genetic diversity in the haemagglutinin (HA) glycoprotein of influenza A viruses (IAVs) of the H9N2 subtype. Twenty-five H9N2 IAVs were isolated from broiler chickens from March to July 2019. The HA gene was amplified, and phylogenetic analysis was performed to determine the evolutionary relationship. Important antigenic amino acid residues of HA attributed to immune escape and zoonotic potential were compared among H9N2 IAVs. Phylogenetic analysis revealed that sublineage B2 under the G1 lineage in Pakistan was found to be diversified, and newly sequenced H9N2 isolates were nested into two clades (A and B). Mutations linked to the antigenic variation and potential immune escape were observed as G72E (1/25, 4%), A180T (3/25, 12%), and A180V (1/25, 4%). A twofold significant reduction (P < 0.01) in log2 hemagglutination inhibition titers was observed with H9N2 IAV naturally harboring amino acid V180 instead of A180 in HA protein. Moreover, in the last 20 years, complete substitution at residues (T127D, D135N, and L150N) and partial substitution at residues (72, 74, 131, 148, 180, 183, 188, 216, 217, and 249, mature H9 HA numbering) associated with changes in antigenicity were observed. The presence of L216 in all H9N2 IAV isolates and T/V180 in four isolates in the receptor-binding site reveals the potential of these viruses to cross the species barrier to infect human or mammals. The current study observed the circulation of antigenically diverse H9N2 IAV variants that possess potential mutations that can escape the host immune system.

Mutual antagonism of mouse-adaptation mutations in HA and PA proteins on H9N2 virus replication

Avian H9N2 viruses have wide host range among the influenza A viruses. However, knowledge of H9N2 mammalian adaptation is limited. To explore the molecular basis of the adaptation to mammals, we performed serial lung passaging of the H9N2 strain A/chicken/Hunan/8.27 YYGK3W3-OC/2018 (3W3) in mice and identified six mutations in the hemagglutinin (HA) and polymerase acidic (PA) proteins. Mutations L226Q, T511I, and A528V of HA were responsible for enhanced pathogenicity and viral replication in mice; notably, HA-L226Q was the key determinant. Mutations T97I, I545V, and S594G of PA contributed to enhanced polymerase activity in mammalian cells and increased viral replication levels in vitro and in vivo. PA-T97I increased viral polymerase activity by accelerating the viral polymerase complex assembly. Our findings revealed that the viral replication was affected by the presence of PA-97I and/or PA-545V in combination with a triple-point HA mutation. Furthermore, the double- and triple-point PA mutations demonstrated antagonistic effect on viral replication when combined with HA-226Q. Notably, any combination of PA mutations, along with double-point HA mutations, resulted in antagonistic effect on viral replication. We also observed antagonism in viral replication between PA-545V and PA-97I, as well as between HA-528V and PA-545V. Our findings demonstrated that several antagonistic mutations in HA and PA proteins affect viral replication, which may contribute to the H9N2 virus adaptation to mice and mammalian cells. These findings can potentially contribute to the monitoring of H9N2 field strains for assessing their potential risk in mammals.

Correlation of avian influenza-H9N2 with high mortality in broiler flocks in the southwest of Tripoli, Libya

Background

Low pathogenic H9N2 avian influenza (LPAI H9N2) caused by the influenza A virus which belongs to the family Orthomyxoviridae. It caused mild respiratory symptoms and a drop in egg production in poultry. Outbreaks of AI-H9N2 have occurred in poultry since the 1990s in many countries in USA, Europe, and Asia. Recently, outbreaks of H9N2 in commercial chicken were recorded in Morocco, Tunisia, Libya, and Egypt. Furthermore, numerous studies demonstrated that co-infection with AI H9N2 and other pathogens results in severe respiratory illness with high mortality in broiler chickens. Outbreaks of respiratory disease with variations in mortality rate were recorded in broiler flocks growing in the southwest of Tripoli in Libya.

Aim

The present study was conducted to explain the variation of mortality rate on broiler flocks growing in the southwest area of Tripoli by detection of AI H9N2 antibodies and antigens.

Methods

A total of 453 sera samples, 60 tracheal swabs, and 60 cloacal swabs were collected from unvaccinated broiler flocks against avian influenza. Specific avian influenza type A antibodies were detected by using the Elisa test, and specific AI-H9N2 antibodies were detected by using the HI test, whereas specific AI-H9N2 antigens were detected in tracheal and cloacal swabs by using One-Step RT-PCR (M gene) technique.

Results

Respiratory diseases with high variations in mortality rate were recorded in broiler flocks growing in the southwest of Tripoli in Libya; the broiler mortality rate in Twisha farms was higher than other farms (62.2% and 11%, respectively). Whereas avian influenza type A antibodies were detected at a high level in Twisha and other farms (95.2%, and 76.7%, respectively). The positive samples for AI type A were tested for AI H9N2 using the HI test. Interestingly the percentage of AI-H9N2 antibodies was quite similar in high and low mortality regions (53.4% and 46.8%, respectively). Additionally, AI-H9N2 antigens were detected only in tracheal swabs in Twisha farm 3, Al-Maamoura, and Ber Al-Tota districts.

Conclusion

This study confirmed the endemic of AI- H9N2 in broiler flocks in the southwest of Tripoli-Libya. Also, it clarified that AI-H9N2 was not responsible for the high mortality rate by itself in broiler flocks. Moreover, this study supported the presence of other subtypes of avian influenza in the studied area.

A replication-deficient H9N2 influenza virus carrying H5 hemagglutinin conferred protection against H9N2 and H5N1 influenza viruses in mice

H5N1 and H9N2 influenza viruses have been reported to cause human infections and are believed to have pandemic potential. The vaccine is an effective tool to prevent influenza virus infection. However, inactivated influenza vaccines sometimes result in low antigenicity as result leads to generating of incomplete immune protection in the form of low cellular and humoral immunity. While the low temperature adapted, traditional live attenuated influenza vaccine (LAIV) is associated with the potential risk to revert to a virulent phenotype, there appears an essential need for an alternative potent methodology to design and develop influenza vaccines with substantial safety and efficacy which may confer solid protection against H9N2 or H5N1 influenza virus infections. In the present study, a replication-deficient recombinant influenza virus, WM01ma-HA(H5), expressing hemagglutinin (HA) of both H9N2 and H5N1 subtypes was developed. The chimeric gene segment expressing HA(H5), was designed using the sequence of an open reading frame (ORF) of HA adopted from A/wild duck/Hunan/021/2005(H5N1)(HN021ma) which was flanked by the NA packaging signals of mouse-adapted strain A/Mink/Shandong/WM01/2014(H9N2)(WM01ma). Due to the absence of ORF of structural protein NA, the replication of this engineered H9N2 influenza viruses WM01ma-HA(H5) was hampered in vitro and in vivo but was well competent in MDCK cells stably expressing the NA protein of WM01ma. Intranasal vaccination of mice with WM01ma-HA(H5) stimulated robust immune response without any clinical signs and conferred complete protection from infection by H5N1 or H9N2 subtype influenza viruses.

Emerging threat and vaccination strategies of H9N2 viruses in poultry in Indonesia: A review

Avian influenza virus subtype H9N2 was first documented in Indonesia in 2017. It has become prevalent in chickens in many provinces of Indonesia as a result of reassortment in live bird markets. Low pathogenic avian influenza subtype H9N2 virus-infected poultry provides a new direction for influenza virus. According to the latest research, the Indonesian H9N2 viruses may have developed through antigenic drift into new genotype, posing a significant hazard to poultry and public health. The latest proof of interspecies transmission proposes that, the next human pandemic variant will be avian influenza virus subtype H9N2. Manipulation and elimination of H9N2 viruses in Indonesia, constant surveillance of viral mutation, and vaccines updates are required to achieve effectiveness. The current review examines should be investigates/assesses/report on the development and evolution of newly identified H9N2 viruses in Indonesia and their vaccination strategy.

Emerging threats and vaccination strategies of H9N2 viruses in poultry in Indonesia: A review

Avian influenza virus subtype H9N2 was first documented in Indonesia in 2017. It has become prevalent in chickens in many provinces of Indonesia as a result of reassortment in live bird markets. Low pathogenic avian influenza subtype H9N2 virus-infected poultry provides a new direction for the influenza virus. According to the latest research, the Indonesian H9N2 viruses may have developed through antigenic drift into a new genotype, posing a significant hazard to poultry and public health. The latest proof of interspecies transmission proposes that the next human pandemic variant will be the avian influenza virus subtype H9N2. Manipulation and elimination of H9N2 viruses in Indonesia, constant surveillance of viral mutation, and vaccine updates are required to achieve effectiveness. The current review examines should be investigates/assesses/report on the development and evolution of newly identified H9N2 viruses in Indonesia and their vaccination strategy.

Coinfection of Chickens with H9N2 and H7N9 Avian Influenza Viruses Leads to Emergence of Reassortant H9N9 Virus with Increased Fitness for Poultry and a Zoonotic Potential

An H7N9 low-pathogenicity avian influenza virus (LPAIV) emerged in 2013 through genetic reassortment between H9N2 and other LPAIVs circulating in birds in China. This virus causes inapparent clinical disease in chickens, but zoonotic transmission results in severe and fatal disease in humans. To examine a natural reassortment scenario between H7N9 and G1 lineage H9N2 viruses predominant in the Indian subcontinent, we performed an experimental coinfection of chickens with A/Anhui/1/2013/H7N9 (Anhui/13) virus and A/Chicken/Pakistan/UDL-01/2008/H9N2 (UDL/08) virus. Plaque purification and genotyping of the reassortant viruses shed via the oropharynx of contact chickens showed H9N2 and H9N9 as predominant subtypes. The reassortant viruses shed by contact chickens also showed selective enrichment of polymerase genes from H9N2 virus. The viable "6+2" reassortant H9N9 (having nucleoprotein [NP] and neuraminidase [NA] from H7N9 and the remaining genes from H9N2) was successfully shed from the oropharynx of contact chickens, plus it showed an increased replication rate in human A549 cells and a significantly higher receptor binding to α2,6 and α2,3 sialoglycans compared to H9N2. The reassortant H9N9 virus also had a lower fusion pH, replicated in directly infected ferrets at similar levels compared to H7N9 and transmitted via direct contact. Ferrets exposed to H9N9 via aerosol contact were also found to be seropositive, compared to H7N9 aerosol contact ferrets. To the best of our knowledge, this is the first study demonstrating that cocirculation of H7N9 and G1 lineage H9N2 viruses could represent a threat for the generation of novel reassortant H9N9 viruses with greater virulence in poultry and a zoonotic potential. IMPORTANCE We evaluated the consequences of reassortment between the H7N9 and the contemporary H9N2 viruses of the G1 lineage that are enzootic in poultry across the Indian subcontinent and the Middle East. Coinfection of chickens with these viruses resulted in the emergence of novel reassortant H9N9 viruses with genes derived from both H9N2 and H7N9 viruses. The "6+2" reassortant H9N9 (having NP and NA from H7N9) virus was shed from contact chickens in a significantly higher proportion compared to most of the reassortant viruses, showed significantly increased replication fitness in human A549 cells, receptor binding toward human (α2,6) and avian (α2,3) sialic acid receptor analogues, and the potential to transmit via contact among ferrets. This study demonstrated the ability of viruses that already exist in nature to exchange genetic material, highlighting the potential emergence of viruses from these subtypes with zoonotic potential.

The PB1 gene from H9N2 avian influenza virus showed high compatibility and increased mutation rate after reassorting with a human H1N1 influenza virus

BACKGROUND

Reassortment between human and avian influenza viruses (AIV) may result in novel viruses with new characteristics that may threaten human health when causing the next flu pandemic. A particular risk may be posed by avian influenza viruses of subtype H9N2 that are currently massively circulating in domestic poultry in Asia and have been shown to infect humans. In this study, we investigate the characteristics and compatibility of a human H1N1 virus with avian H9N2 derived genes.

METHODS

The polymerase activity of the viral ribonucleoprotein (RNP) complex as combinations of polymerase-related gene segments derived from different reassortment events was tested in luciferase reporter assays. Reassortant viruses were generated by reverse genetics. Gene segments of the human WSN-H1N1 virus (A/WSN/1933) were replaced by gene segments of the avian A2093-H9N2 virus (A/chicken/Jiangsu/A2093/2011), which were both the Hemagglutinin (HA) and Neuraminidase (NA) gene segments in combination with one of the genes involved in the RNP complex (either PB2, PB1, PA or NP). The growth kinetics and virulence of reassortant viruses were tested on cell lines and mice. The reassortant viruses were then passaged for five generations in MDCK cells and mice lungs. The HA gene of progeny viruses from different passaging paths was analyzed using Next-Generation Sequencing (NGS).

RESULTS

We discovered that the avian PB1 gene of H9N2 increased the polymerase activity of the RNP complex in backbone of H1N1. Reassortant viruses were able to replicate in MDCK and DF1 cells and mice. Analysis of the NGS data showed a higher substitution rate for the PB1-reassortant virus. In particular, for the PB1-reassortant virus, increased virulence for mice was measured by increased body weight loss after infection in mice.

CONCLUSIONS

The higher polymerase activity and increased mutation frequency measured for the PB1-reassortant virus suggests that the avian PB1 gene of H9N2 may drive the evolution and adaptation of reassortant viruses to the human host. This study provides novel insights in the characteristics of viruses that may arise by reassortment of human and avian influenza viruses. Surveillance for infections with H9N2 viruses and the emergence of the reassortant viruses in humans is important for pandemic preparedness.

Kinetic stability modulation of polymeric nanoparticles for enhanced detection of influenza virus via penetration of viral fusion peptides

Specific interactions between viruses and host cells provide essential insights into material science-based strategies to combat emerging viral diseases. pH-triggered viral fusion is ubiquitous to multiple viral families and is important for understanding the viral infection cycle. Inspired by this process, virus detection has been achieved using nanomaterials with host-mimetic membranes, enabling interactions with amphiphilic hemagglutinin fusion peptides of viruses. Most research has been on designing functional nanoparticles with fusogenic capability for virus detection, and there has been little exploitation of the kinetic stability to alter the ability of nanoparticles to interact with viral membranes and improve their sensing performance. In this study, a homogeneous fluorescent assay using self-assembled polymeric nanoparticles (PNPs) with tunable responsiveness to external stimuli is developed for rapid and straightforward detection of an activated influenza A virus. Dissociation of PNPs induced by virus insertion can be readily controlled by varying the fraction of hydrophilic segments in copolymers constituting PNPs, giving rise to fluorescence signals within 30 min and detection of various influenza viruses, including H9N2, CA04(H1N1), H4N6, and H6N8. Therefore, the designs demonstrated in this study propose underlying approaches for utilizing engineered PNPs through modulation of their kinetic stability for direct and sensitive identification of infectious viruses.

Double mutations in the H9N2 avian influenza virus PB2 gene act cooperatively to increase viral host adaptation and replication for human infections

Avian H9N2 influenza viruses in East Asia are genetically diversified and multiple genotypes (A-W) have been established in poultry. Genotype S strains are currently the most prevalent strains, have caused many human infections and pose a public health threat. In this study, human adaptation mutations in the PB2 polymerase in genotype S strains were identified by database screening. Several PB2 double mutations were identified that acted cooperatively to produce higher genotype S virus polymerase activity and replication in human cells than in avian cells and to increase viral growth and virulence in mice. These mutations were chronologically and phylogenetically clustered in a new group within genotype S viruses. Most of the relevant human virus isolates carry the PB2-A588V mutation together with another PB2 mutation (i.e. K526R, E627V or E627K), indicating a host adaptation advantage for these double mutations. The prevalence of PB2 double mutations in human H9N2 virus isolates has also been found in genetically related human H7N9 and H10N8 viruses. These results suggested that PB2 double mutations in viruses in the field acted cooperatively to increase human adaptation of the currently prevalent H9N2 genotype S strains. This may have contributed to the recent surge of H9N2 infections and may be applicable to the human adaptation of several other avian influenza viruses. Our study provides a better understanding of the human adaptation pathways of genetically related H9N2, H7N9 and H10N8 viruses in nature.

Genetic determinants of receptor-binding preference and zoonotic potential of H9N2 avian influenza viruses

Receptor recognition and binding is the first step of viral infection and a key determinant of host specificity. The inability of avian influenza viruses to effectively bind human-like sialylated receptors is a major impediment to their efficient transmission in humans and pandemic capacity. Influenza H9N2 viruses are endemic in poultry across Asia and parts of Africa where they occasionally infect humans and are therefore considered viruses with zoonotic potential. We previously described H9N2 viruses, including several isolated from human zoonotic cases, showing a preference for human-like receptors. Here we take a mutagenesis approach, making viruses with single or multiple substitutions in H9 haemagglutinin and test binding to avian and human receptor analogues using biolayer interferometry. We determine the genetic basis of preferences for alternative avian receptors and for human-like receptors, describing amino acid motifs at positions 190, 226 and 227 that play a major role in determining receptor specificity, and several other residues such as 159, 188, 193, 196, 198 and 225 that play a smaller role. Furthermore, we show changes at residues 135, 137, 147, 157, 158, 184, 188, and 192 can also modulate virus receptor avidity and that substitutions that increased or decreased the net positive charge around the haemagglutinin receptor-binding site show increases and decreases in avidity, respectively. The motifs we identify as increasing preference for the human-receptor will help guide future H9N2 surveillance efforts and facilitate our understanding of the emergence of influenza viruses with increased zoonotic potential.IMPORTANCE As of 2020, over 60 infections of humans by H9N2 influenza viruses have been recorded in countries where the virus is endemic. Avian-like cellular receptors are the primary target for these viruses. However, given that human infections have been detected on an almost monthly basis since 2015, there may be a capacity for H9N2 viruses to evolve and gain the ability to target human-like cellular receptors. Here we identify molecular signatures that can cause viruses to bind human-like receptors, and we identify the molecular basis for the distinctive preference for sulphated receptors displayed by the majority of recent H9N2 viruses. This work will help guide future surveillance by providing markers that signify the emergence of viruses with enhanced zoonotic potential as well as improving understanding of the basis of influenza virus receptor-binding.

Internal Gene Cassette From a Human-Origin H7N9 Influenza Virus Promotes the Pathogenicity of H9N2 Avian Influenza Virus in Mice

H9N2 avian influenza virus is one of the most widely circulating viruses in poultry and poses a huge potential threat to human health due to its frequent gene reassortment with other influenza viruses. In this study, we generated a series of H9N2-H7N9 reassortant viruses and examined their pathogenicity in a mouse model. We found that HA or combined HA and NA replacement on the H9N2 background led to no substantial change in the virus-induced pathogenicity, whereas H9N2 virus containing H7N9 internal genes had significantly higher virulence in comparison to the parental H9N2 virus. This increased pathogenicity is associated with enhanced viral replication both in mice and in MDCK cells. We further demonstrated that the viral ribonucleoprotein complex from H7N9 virus possessed higher activity than that from its H9N2 counterpart. Collectively, our data demonstrated that genetic compatibility between H9N2 and H7N9 viruses facilitated the reassortment between H7N9 and H9N2 viruses co-circulated in poultry and that internal gene replacement would convert H9N2 virus into a novel threat to human health.

H9 Influenza Viruses: An Emerging Challenge

Influenza A viruses (IAVs) of the H9 subtype are enzootic in Asia, the Middle East, and parts of North and Central Africa, where they cause significant economic losses to the poultry industry. Of note, some strains of H9N2 viruses have been linked to zoonotic episodes of mild respiratory diseases. Because of the threat posed by H9N2 viruses to poultry and human health, these viruses are considered of pandemic concern by the World Health Organization (WHO). H9N2 IAVs continue to diversify into multiple antigenically and phylogenetically distinct lineages that can further promote the emergence of strains with pandemic potential. Somewhat neglected compared with the H5 and H7 subtypes, there are numerous indicators that H9N2 viruses could be involved directly or indirectly in the emergence of the next influenza pandemic. The goal of this work is to discuss the state of knowledge on H9N2 IAVs and to provide an update on the contemporary global situation.

Adaptive amino acid substitutions enable transmission of an H9N2 avian influenza virus in guinea pigs

H9N2 is the most prevalent low pathogenic avian influenza virus (LPAIV) in domestic poultry in the world. Two distinct H9N2 poultry lineages, G1-like (A/quail/Hong Kong/G1/97) and Y280-like (A/Duck/Hong Kong/Y280/1997) viruses, are usually associated with binding affinity for both α 2,3 and α 2,6 sialic acid receptors (avian and human receptors), raising concern whether these viruses possess pandemic potential. To explore the impact of mouse adaptation on the transmissibility of a Y280-like virus A/Chicken/Hubei/214/2017(H9N2) (abbreviated as WT), we performed serial lung-to-lung passages of the WT virus in mice. The mouse-adapted variant (MA) exhibited enhanced pathogenicity and advantaged transmissibility after passaging in mice. Sequence analysis of the complete genomes of the MA virus revealed a total of 16 amino acid substitutions. These mutations distributed across 7 segments including PB2, PB1, PA, NP, HA, NA and NS1 genes. Furthermore, we generated a panel of recombinant or mutant H9N2 viruses using reverse genetics technology and confirmed that the PB2 gene governing the increased pathogenicity and transmissibility. The combinations of 340 K and 588 V in PB2 were important in determining the altered features. Our findings elucidate the specific mutations in PB2 contribute to the phenotype differences and emphasize the importance of monitoring the identified amino acid substitutions due to their potential threat to human health.

Laboratory-Confirmed Avian Influenza A(H9N2) Virus Infection, India, 2019

A 17-month-old boy in India with severe acute respiratory infection was laboratory confirmed to have avian influenza A(H9N2) virus infection. Complete genome analysis of the strain indicated a mixed lineage of G1 and H7N3. The strain also was found to be susceptible to adamantanes and neuraminidase inhibitors.

First report of human infection with avian influenza A(H9N2) virus in Oman: The need for a One Health approach

Following the detection of the first human case of avian influenza A subtype H9N2 in 1998, more than 40 cases were diagnosed worldwide. However, the spread of the virus has been more remarkable and significant in global poultry populations, causing notable economic losses despite its low pathogenicity. Many surveillance studies and activities conducted in several countries have shown the predominance of this virus subtype. We present the case of a 14-month-old female in Oman with an A(H9N2) virus infection. This is the first human case of A(H9N2) reported from Oman and the Gulf Cooperation Countries, and Oman is the second country outside of southern and eastern Asia to report a case (cases have also been detected in Egypt). The patient had bronchial asthma and presented with a high-grade temperature and symptoms of lower respiratory tract infection that necessitated admission to a high dependency unit in a tertiary care hospital. It is of urgency that a multisector One Health approach be established to combat the threat of avian influenza at the animal-human interface. In addition to enhancements of surveillance and control in poultry, there is a need to develop screening and preventive programs for high-risk occupations.

Global patterns of avian influenza A (H7): virus evolution and zoonotic threats

Avian influenza viruses (AIVs) continue to impose a negative impact on animal and human health worldwide. In particular, the emergence of highly pathogenic AIV H5 and, more recently, the emergence of low pathogenic AIV H7N9 have led to enormous socioeconomical losses in the poultry industry and resulted in fatal human infections. While H5N1 remains infamous, the number of zoonotic infections with H7N9 has far surpassed those attributed to H5. Despite the clear public health concerns posed by AIV H7, it is unclear why specifically this virus subtype became endemic in poultry and emerged in humans. In this review, we bring together data on global patterns of H7 circulation, evolution and emergence in humans. Specifically, we discuss data from the wild bird reservoir, expansion and epidemiology in poultry, significant increase in their zoonotic potential since 2013 and genesis of highly pathogenic H7. In addition, we analysed available sequence data from an evolutionary perspective, demonstrating patterns of introductions into distinct geographic regions and reassortment dynamics. The integration of all aspects is crucial in the optimisation of surveillance efforts in wild birds, poultry and humans, and we emphasise the need for a One Health approach in controlling emerging viruses such as AIV H7.

Molecular epidemiology of respiratory viruses in commercial chicken flocks in Pakistan from 2014 through to 2016

Background

Viral diseases are a matter of great concern for poultry farmers in Pakistan. Multiple common viral respiratory diseases (CVRDs) cause huge economic losses in the poultry industry. The prevalence of CVRDs in many countries, including Pakistan, is not clearly understood.

Results

Incidences of 5 chicken respiratory viruses: avian influenza virus (AIV), Newcastle disease virus (NDV/AAVV-1), infectious bronchitis virus (IBV), avian metapneumovirus (aMPV) and infectious laryngotracheitis virus (ILTV) were assessed on commercial Pakistani farms with respiratory problems from 2014 through to 2016. While AIV and AAVV-1 were frequently detected (16 to 17% of farms), IBV and aMPV were rarely detected (in 3 to 5% of farms) and ILTV was not detected. We characterized H9 AIV of the G1 lineage, genotype VII AAVV-1, GI-13 IBV, and type B aMPV strains with very little genetic variability in the 2-year study period. Co-infections with AIV and AAVV-1 were common and wild type AAVV-1 was detected despite the use of vaccines. Control measures to limit the virus burden in chicken flocks are discussed.

Conclusions

Our data shows that AIV (H9), AAVV-1, IBV and aMPV are prevalent in commercial poultry in Pakistan. Further studies are necessary to assess circulating strains, economic losses caused by infections and coinfections of these pathogens, and the costs and benefits of countermeasures. Furthermore, veterinarians and farmers should be informed of the pathogens circulating in the field and hence advised on the use of vaccines.

Amantadine resistance markers among low pathogenic avian influenza H9N2 viruses isolated from poultry in India, during 2009-2017

Antiviral susceptibility screening of avian influenza (AI) H9N2 viruses is crucial considering their role at the animal-human interface and potential to cause human infections. The Matrix 2 (M2) inhibitors (amantadine and rimantadine) have been used for prophylaxis and treatment of influenza A virus infections, however, resistance to these drugs has been widely reported. Information about amantadine susceptibility of H9N2 viruses from India is scanty. Matrix genes of 48H9N2 viruses isolated from India during 2009-2017 were sequenced and M2 trans-membrane region sequences were screened for mutations which are known to confer resistance to amantadine namely, L26F, V27A, A30 T/V, S31N and G34E. All the viruses isolated during the year 2009 were sensitive to amantadine. However, resistance started to appear since the year 2010 and all the viruses isolated from the year 2015 onwards showed presence of molecular markers conferring resistance to amantadine. Majority of the resistant viruses exhibited S31 N mutation. Four isolates showed presence of V27A + S31 N dual mutations. Comparison of the M2 sequences from other Asian countries showed different patterns of amantadine resistance wherein phylogenetic analysis of the M genes of the strains from Pakistan formed a separate cluster. In conclusion, the present study reports prevalence and gradual increase of amantadine resistance among AI H9N2 viruses in India, emphasizing the importance of the antiviral surveillance.

Genome Sequences of an H9N2 Avian Influenza Virus Strain Found in Pakistan in 2017

In 2017, we isolated an H9N2 avian influenza virus in Pakistan. Genetic analysis showed that the A/chicken/Kasoor/SI36/2017(H9N2) isolate belongs to the G1 lineage. In addition, this isolate possesses mammalian host-specific mutations which could possibly favor interspecies transmission, suggesting that Pakistani H9N2 viruses are still potentially infectious for mammals.

In 2017, we isolated an H9N2 avian influenza virus in Pakistan. Genetic analysis showed that the A/chicken/Kasoor/SI36/2017(H9N2) isolate belongs to the G1 lineage. In addition, this isolate possesses mammalian host-specific mutations which could possibly favor interspecies transmission, suggesting that Pakistani H9N2 viruses are still potentially infectious for mammals.

A Global Perspective on H9N2 Avian Influenza Virus

H9N2 avian influenza viruses have become globally widespread in poultry over the last two decades and represent a genuine threat both to the global poultry industry but also humans through their high rates of zoonotic infection and pandemic potential. H9N2 viruses are generally hyperendemic in affected countries and have been found in poultry in many new regions in recent years. In this review, we examine the current global spread of H9N2 avian influenza viruses as well as their host range, tropism, transmission routes and the risk posed by these viruses to human health.

Adlhoch C, Kuiken T, Monne I, Mulatti P, Smietanka K, Staubach C, Guajardo IM, Baldinelli F. Avian influenza overview November 2018 - February 2019

No human infections due to highly pathogenic avian influenza (HPAI) A(H5N8) or A(H5N6) viruses ‐ detected in wild birds and poultry outbreaks in Europe ‐ have been reported so far and the risk of zoonotic transmission to the general public in Europe is considered very low. Between 16 November 2018 and 15 February 2019, two HPAI A(H5N8) outbreaks in poultry establishments in Bulgaria, two HPAI A(H5N6) outbreaks in wild birds in Denmark and one low pathogenic avian influenza (LPAI) A(H5N3) in captive birds in the Netherlands were reported in the European Union (EU). Genetic characterisation of the HPAI A(H5N6) viruses reveals that they cluster with the A(H5N6) viruses that have been circulating in Europe since December 2017. The wild bird species involved were birds of prey and were likely infected due to hunting or scavenging infected wild waterfowl. However, HPAI virus was not detected in other wild birds during this period. Outside the EU, two HPAI outbreaks were reported in poultry during the reporting period from western Russia. Sequence information on an HPAI A(H5N6) virus found in a common gull in western Russia in October 2018 suggests that the virus clusters within clade 2.3.4.4c and is closely related to viruses that transmitted zoonotically in China. An increasing number of outbreaks in poultry and wild birds in Asia, Africa and the Middle East was observed during the time period for this report. Currently there is no evidence of a new HPAI virus incursion from Asia into Europe. However, passive surveillance systems may not be sensitive enough if the prevalence or case fatality in wild birds is very low. Nevertheless, it is important to encourage and maintain a certain level of passive surveillance in Europe testing single sick or dead wild birds and birds of prey as they may be sensitive sentinel species for the presence of HPAI virus in the environment. A well‐targeted active surveillance might complement passive surveillance to collect information on HPAI infectious status of apparently healthy wild bird populations.