Multiple Avian Influenza Viruses Research Articles

Detection of clade 2.3.4.4 highly pathogenic avian influenza H5 viruses in healthy wild birds in the Hadeji-Nguru wetland, Nigeria 2022.

The introduction of multiple avian influenza virus (AIV) subtypes into Nigeria has resulted in several poultry outbreaks purportedly linked to trade and wild birds. The role of wild birds in perpetuating AIV in Nigeria was, therefore, elucidated. A cross-sectional study was conducted among wild aquatic bird species at the Hadejia-Nguru wetlands in Northeastern Nigeria between March and April 2022. A total of 452 swabs (226 cloacae and 226 oropharyngeal) were collected using a mist net to capture the birds. These samples were tested by RT-qPCR, followed by sequencing. Highly pathogenic AIV of the H5N1 subtype was identified in clinically healthy wild bird species, namely, African jacana, ruff, spur-winged goose, squared-tailed nightjar, white-faced whistling ducks, and white stork. A prevalence of 11.1% (25/226) was recorded. Phylogenetic analysis of the complete HA gene segment indicated the presence of clade 2.3.4.4b. However, these H5N1 viruses characterized from these wild birds cluster separately from the H5N1 viruses characterized in Nigerian poultry since early 2021. Specifically, the viruses form two distinct genetic groups both linked with the Eurasian H5N1 gene pool but likely resulting from two distinct introductions of the virus in the region. Whole-genome characterization of the viruses reveals the presence of mammalian adaptive marker E627K in two Afro-tropical resident aquatic ducks. This has zoonotic potential. Our findings highlight the key role of surveillance in wild birds to monitor the diversity of viruses in this area, provide the foundations of epidemiological understanding, and facilitate risk assessment.

Paper-based electrochemical immunosensor for label-free detection of multiple avian influenza virus antigens using flexible screen-printed carbon nanotube-polydimethylsiloxane electrodes

Many studies have been conducted on measuring avian influenza viruses and their hemagglutinin (HA) antigens via electrochemical principles; most of these studies have used gold electrodes on ceramic, glass, or silicon substrates, and/or labeling for signal enhancement. Herein, we present a paper-based immunosensor for label-free measurement of multiple avian influenza virus (H5N1, H7N9, and H9N2) antigens using flexible screen-printed carbon nanotube-polydimethylsiloxane electrodes. These flexible electrodes on a paper substrate can complement the physical weakness of the paper-based sensors when wetted, without affecting flexibility. The relative standard deviation of the peak currents was 1.88% when the electrodes were repeatedly bent and unfolded twenty times with deionized water provided each cycle, showing the stability of the electrodes. For the detection of HA antigens, approximately 10-μl samples (concentration: 100 pg/ml–100 ng/ml) were needed to form the antigen–antibody complexes during 20–30 min incubation, and the immune responses were measured via differential pulse voltammetry. The limits of detections were 55.7 pg/ml (0.95 pM) for H5N1 HA, 99.6 pg/ml (1.69 pM) for H7N9 HA, and 54.0 pg/ml (0.72 pM) for H9N2 HA antigens in phosphate buffered saline, and the sensors showed good selectivity and reproducibility. Such paper-based sensors are economical, flexible, robust, and easy-to-manufacture, with the ability to detect several avian influenza viruses.

Avian Influenza Virus Status and Maternal Antibodies in Nestling White Ibis (Eudocimus albus)

The White Ibis (Eudocimus albus), a nomadic wading bird, has increased its exploitation of urban habitats in South Florida, United States, and has recently established several urban breeding colonies. Certain characteristics of ibis ecology could position them in the natural cycle of the avian influenza virus (AIV). In fact, experimentally infected ibises were shown to be competent hosts for multiple AIV subtypes, and seroconversion to AIV has been documented in adult ibises in natural populations. However, the mechanisms of transmission and the timing of infection are unclear as we have yet to isolate AIV from a free-living ibis. To investigate the age-specific AIV dynamics of ibis, we captured nestlings (n = 115) weekly for 1–4 weeks from urban and natural settings in 2020 and 2021. We collected choanal/cloacal swabs for rRT-PCR and virus isolation, and plasma to screen for maternal AIV antibodies. AIV was not detected in any individual by virus isolation; however, maternal antibodies to AIV were detected in 95% of nestlings, with varying rates of catabolism. These results confirm that nestlings are afforded maternal antibodies from adults at rates reflective of higher adult seroprevalence than previously documented and that nestlings in breeding colonies may have some degree of protection and are unlikely to become infected with AIV.

Migratory birds in southern Brazil are a source of multiple avian influenza virus subtypes.

BackgroundThere is insufficient knowledge about the relation of avian influenza virus (AIV) to migratory birds in South America. Accordingly, we studied samples obtained over a 4‐year period (2009‐2012) from wild birds at a major wintering site in southern Brazil.MethodsWe obtained 1212 oropharyngeal/cloacal samples from wild birds at Lagoa do Peixe National Park and screened them for influenza A virus by RT‐PCR amplification of the matrix gene. Virus isolates were subjected to genomic sequencing and antigenic characterization.ResultsForty‐eight samples of 1212 (3.96%) contained detectable influenza virus RNA. Partial viral sequences were obtained from 12 of these samples, showing the presence of H2N2 (1), H6Nx (1), H6N1 (8), H9N2 (1), and H12N5 (1) viruses. As H6 viruses predominated, we generated complete genomes from all 9 H6 viruses. Phylogenetic analyses showed that they were most similar to viruses of South American lineage. The H6N1 viruses caused no disease signs in infected ferrets and, despite genetic differences, were antigenically similar to North American isolates.ConclusionsLagoa do Peixe National Park is a source of multiple AIV subtypes, with the levels of influenza virus in birds being highest at the end of their wintering period in this region. H6N1 viruses were the predominant subtype identified. These viruses were more similar to viruses of South American lineage than to those of North American lineage.

LabVIEW-based impedance biosensing system for detection of avian influenza virus

In order to detect the multiple avian influenza viruses (AIVs) rapidly, specifically and sensitively, a LabVIEW and microelectrode array-based impedance biosensor was developed and demonstrated. A laptop with LabVIEW software was used to generate excitation signals at different frequencies with an audio card and measure the impedance of target viruses through a data acquisition card. The audio card of the laptop was used as a function generator, while a data acquisition card was used for data communication. A virtual instrument was programmed with LabVIEW to provide a platform for impedance measurement, data processing, and control. Six interdigitated microelectrodes were placed at the bottom of six wells on a microplate to form six sensors for different AIVs and controls. Then, AIV specific ligands were immobilized on the microelectrode surface to capture target viruses. To enhance the sensitivity, AIV specific aptamers conjugated gold nanoparticles and thiocyanuric acid were employed to form a network structure and used as an amplifier. Results of the measured impedance were compared with a commercial IM6 impedance analyzer, and the error was less than 5%. The developed biosensor was portable with the sensitivity and specificity for applications to on-site or in-field rapid screening of avian influenza viruses. Keywords: biosensor, impedance detection, avian influenza virus, LabVIEW DOI: 10.3965/j.ijabe.20160904.1704 Citation: Zhang B H, Wang R H, Wang Y X, Li Y B. LabVIEW-based impedance biosensing system for detection of avian influenza virus. Int J Agric & Biol Eng, 2016; 9(4): 116－122.

Circulation of reassortant influenza A(H7N9) viruses in poultry and humans, Guangdong Province, China, 2013.

Influenza A(H7N9) virus emerged in eastern China in February 2013 and continues to circulate in this region, but its ecology is poorly understood. In April 2013, the Guangdong Provincial Center for Disease Control and Prevention (CDC) implemented environmental and human syndromic surveillance for the virus. Environmental samples from poultry markets in 21 city CDCs (n = 8,942) and respiratory samples from persons with influenza-like illness or pneumonia (n = 32,342) were tested; viruses isolated from 6 environmental samples and 16 patients were sequenced. Sequence analysis showed co-circulation of 4 influenza A(H7N9) virus strains that evolved by reassortment with avian influenza A(H9N2) viruses circulating in this region. In addition, an increase in human cases starting in late 2013 coincided with an increase in influenza A H7 virus isolates detected by environmental surveillance. Co-circulation of multiple avian influenza viruses that can infect humans highlights the need for increased surveillance of poultry and potential environmental sources.

Serological report of influenza A (H7N9) infections among pigs in Southern China.

BackgroundIn 2013, a novel H7N9 avian influenza virus (AIV) was isolated from ill humans in Shanghai and Anhui Province, China. Since then, the virus has spread quickly throughout China. Previous isolation of H7N2 virus from swine suggests that additional H7 subtype AIVs may be transmitted through pigs. However, prior to the recent zoonosis of H7N9, there were very few studies on the seroprevalence of the H7 subtypes in this species. Thus, there is a need to perform serological surveys for novel H7N9 as well as other H7 subtype AIVs in swine. This surveillance may help us understand risk factors for outbreaks of influenza A (H7N9) virus.ResultsOnly 2.0% (26/1310) of the pig sera had antibodies with an HI titer ≥1:20, and none had an MN titer ≥1:80, against the H7 antigen. Thus, no samples were found to be positive against H7N9. However, 13.6% (178/1310) of the pig sera had antibodies with HI titer ≥1:20 and 8.5% (112/1310) by MN titer ≥1:80 against H9 antigen. Thirty-seven percent (484/1310) of the pig sera had antibodies with HI titer ≥1:20 and 18.2% (238/1310) had MN titer ≥1:80 against pandemic 2009.ConclusionsPigs in southern China have been shown to be infected with multiple avian influenza viruses. As the prevalence of novel influenza A viruses (e.g., H7N9 avian influenza virus) may be increasing among poultry in China, similar seroepidemiological studies of pigs should be conducted in the future.

Intranasal vaccination with H5, H7 and H9 hemagglutinins co-localized in a virus-like particle protects ferrets from multiple avian influenza viruses

Avian influenza H5, H7 and H9 viruses top the World Health Organization's (WHO) list of subtypes with the greatest pandemic potential. Here we describe a recombinant virus-like particle (VLP) that co-localizes hemagglutinin (HA) proteins derived from H5N1, H7N2, and H9N2 viruses as an experimental vaccine against these viruses. A baculovirus vector was configured to co-express the H5, H7, and H9 genes from A/Viet Nam/1203/2004 (H5N1), A/New York/107/2003 (H7N2) and A/Hong Kong/33982/2009 (H9N2) viruses, respectively, as well as neuraminidase (NA) and matrix (M1) genes from A/Puerto Rico/8/1934 (H1N1) virus. Co-expression of these genes in Sf9 cells resulted in production of triple-subtype VLPs containing HA molecules derived from the three influenza viruses. The triple-subtype VLPs exhibited hemagglutination and neuraminidase activities and morphologically resembled influenza virions. Intranasal vaccination of ferrets with the VLPs resulted in induction of serum antibody responses and efficient protection against experimental challenges with H5N1, H7N2, and H9N2 viruses.

Serological surveillance reveals widespread influenza A H7 and H9 subtypes among chicken flocks in Egypt

Multiple avian influenza viruses' subtypes are circulating worldwide possessing serious threat to human populations and considered key contributors to the emergence of human influenza pandemics. This study aimed to identify the potential existence of H7 and H9 avian influenza infections circulating among chicken flocks in Egypt. Serum samples were collected from chicken flocks that experienced respiratory distresses and/or variable mortality rates. H7 and H9 virus infections were screened by haemagglutination inhibition assay using chicken erythrocytes. Serum samples were collected from 9 broiler, 12 breeder and 18 layer flocks. Out of 1,225 examined sera, 417 (34 %) from 14 flocks and 605 (49.4 %) from 21 flocks were found positive for H7 and H9, respectively. Prevalence of both H7 and H9 antibodies were higher in layer followed by breeder then broiler flocks. Special consideration should be paid to control influenza viruses in Egypt, as pandemic influenza strains may develop unnoticed given the presence of subclinical infections, and the possibility of re-assortment with the prevailing endemic H5N1 virus strains in Egypt do exist.

Infection With Multiple Avian Influenza Viruses in a Man Without Poultry-Handling Practices Suggesting an Increased Probability of Emergent Pandemic Influenza Virus in General Population

Infection With Multiple Avian Influenza Viruses in a Man Without Poultry-Handling Practices Suggesting an Increased Probability of Emergent Pandemic Influenza Virus in General Population

Homo- and Heterosubtypic Low Pathogenic Avian Influenza Exposure on H5N1 Highly Pathogenic Avian Influenza Virus Infection in Wood Ducks (Aix sponsa)

Wild birds in the Orders Anseriformes and Charadriiformes are the natural reservoirs for avian influenza (AI) viruses. Although they are often infected with multiple AI viruses, the significance and extent of acquired immunity in these populations is not understood. Pre-existing immunity to AI virus has been shown to modulate the outcome of a highly pathogenic avian influenza (HPAI) virus infection in multiple domestic avian species, but few studies have addressed this effect in wild birds. In this study, the effect of pre-exposure to homosubtypic (homologous hemagglutinin) and heterosubtypic (heterologous hemagglutinin) low pathogenic avian influenza (LPAI) viruses on the outcome of a H5N1 HPAI virus infection in wood ducks (Aix sponsa) was evaluated. Pre-exposure of wood ducks to different LPAI viruses did not prevent infection with H5N1 HPAI virus, but did increase survival associated with H5N1 HPAI virus infection. The magnitude of this effect on the outcome of the H5N1 HPAI virus infection varied between different LPAI viruses, and was associated both with efficiency of LPAI viral replication in wood ducks and the development of a detectable humoral immune response. These observations suggest that in naturally occurring outbreaks of H5N1 HPAI, birds with pre-existing immunity to homologous hemagglutinin or neuraminidase subtypes of AI virus may either survive H5N1 HPAI virus infection or live longer than naïve birds and, consequently, could pose a greater risk for contributing to viral transmission and dissemination. The mechanisms responsible for this protection and/or the duration of this immunity remain unknown. The results of this study are important for surveillance efforts and help clarify epidemiological data from outbreaks of H5N1 HPAI virus in wild bird populations.

The public health impact of avian influenza viruses

Influenza viruses with novel hemagglutinin and 1 or more accompanying genes derived from avian influenza viruses sporadically emerge in humans and have the potential to result in a pandemic if the virus causes disease and spreads efficiently in a population that lacks immunity to the novel hemagglutinin. Since 1997, multiple avian influenza virus subtypes have been transmitted directly from domestic poultry to humans and have caused a spectrum of human disease, from asymptomatic to severe and fatal. To assess the pandemic risk that avian influenza viruses pose, we have used multiple strategies to better understand the capacity of avian viruses to infect, cause disease, and transmit among mammals, including humans. Seroepidemiologic studies that evaluate the frequency and risk of human infection with avian influenza viruses in populations with exposure to domestic or wild birds can provide a better understanding of the pandemic potential of avian influenza subtypes. Investigations conducted in Hong Kong following the first H5N1 outbreak in humans in 1997 determined that exposure to poultry in live bird markets was a key risk factor for human disease. Among poultry workers, butchering and exposure to sick poultry were risk factors for antibody to H5 virus, which provided evidence for infection. A second risk assessment tool, the ferret, can be used to evaluate the level of virulence and potential for host-to-host transmission of avian influenza viruses in this naturally susceptible host. Avian viruses isolated from humans exhibit a level of virulence and transmissibility in ferrets that generally reflects that seen in humans. The ferret model thus provides a means to monitor emerging avian influenza viruses for pandemic risk, as well as to evaluate laboratory-generated reassortants and mutants to better understand the molecular basis of influenza virus transmissibility. Taken together, such studies provide valuable information with which we can assess the public health risk of avian influenza viruses.

An avian live attenuated master backbone for potential use in epidemic and pandemic influenza vaccines

The unprecedented emergence in Asia of multiple avian influenza virus (AIV) subtypes with a broad host range poses a major challenge in the design of vaccination strategies that are both effective and available in a timely manner. The present study focused on the protective effects of a genetically modified AIV as a source for the preparation of vaccines for epidemic and pandemic influenza. It has previously been demonstrated that a live attenuated AIV based on the internal backbone of influenza A/Guinea fowl/Hong Kong/WF10/99 (H9N2), called WF10att, is effective at protecting poultry species against low- and high-pathogenicity influenza strains. More importantly, this live attenuated virus provided effective protection when administered in ovo. In order to characterize the WF10att backbone further for use in epidemic and pandemic influenza vaccines, this study evaluated its protective effects in mice. Intranasal inoculation of modified attenuated viruses in mice provided adequate protective immunity against homologous lethal challenges with both the wild-type influenza A/WSN/33 (H1N1) and A/Vietnam/1203/04 (H5N1) viruses. Adequate heterotypic immunity was also observed in mice vaccinated with modified attenuated viruses carrying H7N2 surface proteins. The results presented in this report suggest that the internal genes of a genetically modified AIV confer similar protection in a mouse model and thus could be used as a master donor strain for the generation of live attenuated vaccines for epidemic and pandemic influenza.

Pathogens Transmitted by Migratory Birds: Threat Perceptions to Poultry Health and Production

Pathogens Transmitted by Migratory Birds: Threat Perceptions to Poultry Health and Production