Surveillance of Live Poultry Markets for Low Pathogenic Avian Influenza Viruses in Guangxi Province, Southern China, from 2012-2015

Isolation and genetic characteristics of Novel H4N1 Avian Influenza viruses in ChongQing, China

BACKGROUND

Avian influenza viruses (AIVs) constitute significant zoonotic pathogens encompassing a broad spectrum of subtypes. Notably, the H4 subtype of AIVs has a pronounced ability to shift hosts. The escalating prevalence of the H4 subtype heightens the concern for its zoonotic potential, signaling an urgent need for vigilance.

METHODS

During the period from December 2021 to November 2023, we collected AIV-related environmental samples and assessed them using a comprehensive protocol that included nucleic acid testing, gene sequencing, isolation culture, and resequencing.

RESULTS

In this study, a total of 934 environmental samples were assessed, revealing a remarkably high detection rate (43.66%, 289/662) of AIV in the live poultry market. Notably, the H4N1 subtype AIV (cs2301) was isolated from the live poultry market and its complete genome sequence was successfully determined. Subsequent analysis revealed that cs2301, resulting from a reassortment event between wild and domesticated waterfowl, exhibits multiple mutations and demonstrates potential for host transfer.

CONCLUSIONS

Our research once again demonstrates the significant role of wild and domesticated waterfowl in the reassortment process of avian influenza virus, enriching the research on the H4 subtype of AIV, and emphasizing the importance of proactive monitoring the environment related to avian influenza virus.

Cross-Species Transmission Potential of H4 Avian Influenza Viruses in China: Epidemiological and Evolutionary Study

H4 avian influenza viruses (AIVs) have been widely detected in live poultry markets in China. However, the potential public health impact of H4 AIVs remains largely uncertain. Here, we fully analyzed the distribution and phylogenetic relationship of H4 AIVs in China. We obtained 31 isolates of H4 viruses in China during 2009-2022 through surveillance in poultry-associated environments, such as live poultry markets and poultry farms. Genomic sequence analysis together with publicly available data revealed that frequent reassortment and introduction of H4 AIV from wild birds to poultry may have occurred. We identified 62 genotypes among 127 whole genome sequences of H4 viruses in China, indicating that H4 AIVs had great genetic diversity in China. We also investigated molecular markers and found that drug resistance mutations frequently occurred in the M2 protein and a few mutations related to receptor binding and the host signature in H4 AIVs. Our study demonstrates the cross-species transmission potential of H4 AIVs in China and provides some reference significance for its risk assessment.

Phylogeny and Pathogenicity of Subtype XIIb NDVs from Francolins in Southwestern China and Effective Protection by an Inactivated Vaccine

Most genotype XII newcastle disease viruses (NDVs) were isolated from poultry, chickens, or geese, with the exception of one subtype, XIIa NDV, which was isolated from a peacock. Here, two subtype XIIb NDVs, francolin/China/GX01/2017 and francolin/China/GX02/2017 (GX01 and GX02 hereafter), were isolated from francolins, which are resident birds in southern China. GX01 and GX02 were characterized as velogenic NDVs. Based on the weaker pathogenicity of these viruses in chickens, the amino acid sequences of seven proteins from genotype XII NDVs were compared, which revealed 17, 40, 15, 7, 32, 25, and 31 variations in the NP, P, M, F, HN, L, and V proteins, respectively, some of which could be responsible for this decreased pathogenicity. Epidemiological and phylogenetic analyses suggest that subtype XIIb NDVs have multiple transmission chains, and that resident birds may be involved in this process as intermediate hosts in which viruses keep evolving. Because of the increased pathogenicity of subtype XIIb NDVs, the protective efficacy of GX01 as an inactivated vaccine was evaluated and compared with that of two commercial inactivated vaccines in chickens. The results showed that the subtype XIIb NDVs could be candidate genotype-matched vaccine strains against genotype XII NDVs.

Avian influenza A virus H7N9 in China, a role reversal from reassortment receptor to the donator

Reassortment can introduce one or more gene segments of influenza A viruses (IAVs) into another, resulting in novel subtypes. Since 2013, a new outbreak of human highly pathogenic avian influenza has emerged in the Yangtze River Delta (YRD) and South-Central regions of China. In this study, using Anhui province as an example, we discuss the possible impact of H7N9 IAVs on future influenza epidemics through a series of gene reassortment events. Sixty-one human H7N9 isolates were obtained from five outbreaks in Anhui province from 2013 to 2019. Bioinformatics analyses revealed that all of them were characterized by low pathogenicity and high human or mammalian tropism and had introduced novel avian influenza A virus (AIV) subtypes such as H7N2, H7N6, H9N9, H5N6, H6N6, and H10N6 through gene reassortment. In reassortment events, Anhui isolates may donate one or more segments of HA, NA, and the six internal protein-coding genes for the novel subtype AIVs. Our study revealed that H7N9, H9N2, and H5N1 can serve as stable and persistent gene pools for AIVs in the YRD and South-Central regions of China. Novel AIV subtypes might be generated continuously by reassortment. These AIVs may have obtained human-type receptor-binding abilities from their donors and prefer binding to them, which can cause human epidemics through accidental spillover infections. Facing the continual threat of emerging avian influenza, constant monitoring of AIVs should be conducted closely for agricultural and public health.

An Enzyme-Free Sandwich Amperometry-Type Immunosensor Based on Au/Pt Nanoparticle-Functionalized Graphene for the Rapid Detection of Avian Influenza Virus H9 Subtype

Avian influenza virus H9 subtype (AIV H9) has contributed to enormous economic losses. Effective diagnosis is key to controlling the spread of AIV H9. In this study, a nonenzymatic highly electrocatalytic material was prepared using chitosan (Chi)-modified graphene sheet (GS)-functionalized Au/Pt nanoparticles (GS-Chi-Au/Pt), followed by the construction of a novel enzyme-free sandwich electrochemical immunosensor for the detection of AIV H9 using GS-Chi-Au/Pt and graphene-chitosan (GS-Chi) nanocomposites as a nonenzymatic highly electrocatalytic material and a substrate material to immobilize capture antibodies (avian influenza virus H9-monoclonal antibody, AIV H9/MAb), respectively. GS, which has a large specific surface area and many accessible active sites, permitted multiple Au/Pt nanoparticles to be attached to its surface, resulting in substantially improved conductivity and catalytic ability. Au/Pt nanoparticles can provide modified active sites for avian influenza virus H9-polyclonal antibody (AIV H9/PAb) immobilization as signal labels. Upon establishing the electrocatalytic activity of Au/Pt nanoparticles on graphene towards hydrogen peroxide (H₂O₂) reduction for signal amplification and optimizing the experimental parameters, we developed an AIV H9 electrochemical immunosensor, which showed a wide linear range from 10^1.37 EID₅₀ mL^-1 to 10^6.37 EID₅₀ mL^-1 and a detection limit of 10^0.82 EID₅₀ mL^-1. This sandwich electrochemical immunosensor also exhibited high selectivity, reproducibility and stability.

Evidence for flock transmission of individual subtypes and strains of avian influenza viruses: A monitoring study of wild birds in Kazakhstan

An active surveillance study of avian influenza viruses (AIVs) in wild birds was carried out in Kazakhstan in 2018-2019. In total, 866 samples were collected from wild birds and analyzed for influenza viruses using molecular and virological tests. Genome segments of Asian, European, and Australian lineages were detected in 25 (4.6%) out of 541 waterfowl samples positive for subtype H3N8, and in two (0.6%) out of 325 H3N8 positive samples from terrestrial birds. No highly pathogenic avian influenza virus (AIV) was detected. The results indicated transmission of closely related strains or identical subtypes of AIVs by a flock-unit of migratory birds or annual cyclical pattern of subtype dominance. The simultaneous circulation of genome segments of the Asian, European and Australian genetic lineages of H3N8 AIVs in wild birds in Kazakhstan indicated the important role of Central Asia as a transmission hub of AI viruses linking the East Asian migratory flyways with European flyways and vice versa.

Detection of Chicken Respiratory Pathogens in Live Markets of Addis Ababa, Ethiopia, and Epidemiological Implications

A moderate to high seroprevalence of exposure to Newcastle disease (NDV), avian metapneumovirus (aMPV), infectious laryngotracheitis virus (ILTV), infectious bronchitis virus (IBV) and Mycoplasma gallisepticum (MG) has recently been reported in Ethiopia, but it is unclear to what extent these contribute to clinical cases of respiratory disease. This study investigated the presence of these pathogens in chickens exhibiting respiratory disease in two live markets in Addis Ababa. Markets were visited weekly for three months, and 18 chickens displaying respiratory clinical signs were acquired. Swab samples were taken from the choana, trachea, air sac and larynx for bacteriology and PCR tests targeting these five pathogens. PCR-positive samples were sequenced. All 18 chickens were PCR-positive for aMPV, 50% for each of Mg and NDV, 39% for IBV and 11% for ILTV. Infections with >3 pathogens were detected in 17 of 18 chickens. Potentially pathogenic bacteria such as Escherichia coli, Klebsiella spp., Streptococcus spp. and Staphylococcus were found in 16 to 44% of chickens. IBV-positive samples were of the 793B genotype. The results associate the presence of these organisms with clinical respiratory disease and are consistent with recent serological investigations, indicating a high level of exposure to multiple respiratory pathogens.

Two Novel Avian Influenza Virus Subtypes Isolated from Domestic Ducks in North of Iran

Avian Influenza Viruses (AIV) are the causative agents of Avian Influenza (AI), which is a contagious and zoonotic disease in birds. Among birds, wild waterfowls and ducks are the primary and natural reservoirs of low pathogenic avian influenza viruses (LPAI). This study aimed to identify and differentiate between two AIV subtypes (i.e., hemagglutinin and neuraminidase from domestic ducks by hemagglutinin inhibition (HI) and neuraminidase inhibition (NI) assays. To this end, 962 cloacal swabs were collected from domestic ducks being sold at different Iranian Live Bird Markets in Gilan, Mazandaran, and Golestan provinces, located at the southern coast of the Caspian Sea. The samples were inoculated in 10-day-old embryonated specific pathogen-free chicken eggs, and subsequently, harvested allantoic fluids were subjected to agar gel immunodiffusion, HI, and NI assays. In total, five positive samples, including two H4N2 and three H3N2 AIV subtypes were identified. Isolation of H4N2 and H3N2 viruses has never been reported from Iranian domestic ducks previously. This finding further suggests the diversity of LPAI viruses in Iranian ducks and also shows that the HI and NI assays are highly efficient in determining AIV subtypes.

Survey of low pathogenic avian influenza viruses in live poultry markets in Guangxi Province, Southern China, 2016-2019

Low pathogenic avian influenza viruses (LPAIVs) have been widespread in poultry and wild birds throughout the world for many decades. LPAIV infections are usually asymptomatic or cause subclinical symptoms. However, the genetic reassortment of LPAIVs may generate novel viruses with increased virulence and cross-species transmission, posing potential risks to public health. To evaluate the epidemic potential and infection landscape of LPAIVs in Guangxi Province, China, we collected and analyzed throat and cloacal swab samples from chickens, ducks and geese from the live poultry markets on a regular basis from 2016 to 2019. Among the 7,567 samples, 974 (12.87%) were LPAIVs-positive, with 890 single and 84 mixed infections. Higher yearly isolation rates were observed in 2017 and 2018. Additionally, geese had the highest isolation rate, followed by ducks and chickens. Seasonally, spring had the highest isolation rate. Subtype H3, H4, H6 and H9 viruses were detected over prolonged periods, while H1 and H11 viruses were detected transiently. The predominant subtypes in chickens, ducks and geese were H9, H3, and H6, respectively. The 84 mixed infection samples contained 22 combinations. Most mixed infections involved two subtypes, with H3 + H4 as the most common combination. Our study provides important epidemiological data regarding the isolation rates, distributions of prevalent subtypes and mixed infections of LPAIVs. These results will improve our knowledge and ability to control epidemics, guide disease management strategies and provide early awareness of newly emerged AIV reassortants with pandemic potential.

Evolution and pathogenicity of H6 avian influenza viruses isolated from Southern China during 2011 to 2017 in mice and chickens

H6 subtype avian influenza viruses spread widely in birds and pose potential threats to poultry and mammals, even to human beings. In this study, the evolution and pathogenicity of H6 AIVs isolated in live poultry markets from 2011 to 2017 were investigated. These H6 isolates were reassortant with other subtypes of influenza virus with increasing genomic diversity. However, no predominant genotype was found during this period. All of the H6N2 and most of the H6N6 isolates replicated efficiently in lungs of inoculated mice without prior adaptation. All of the H6N2 and two H6N6 isolates replicated efficiently in nasal turbinates of inoculated mice, which suggested the H6N2 viruses were more adaptive to the upper respiratory tract of mice than the H6N6 viruses. One of H6N2 virus caused systemic infection in one out of three inoculated mice, which indicated that H6 avian influenza virus, especially the H6N2 viruses posed a potential threat to mammals. Five H6 strains selected from different genotypes caused no clinical signs to inoculated chickens, and their replication were limited in chickens since the viruses have been detected only from a few tissues or swabs at low titers. Our study strongly suggests that the H6 avian influenza virus isolated from live poultry markets pose potential threat to mammals.

Dominant subtype switch in avian influenza viruses during 2016-2019 in China

We have surveyed avian influenza virus (AIV) genomes from live poultry markets within China since 2014. Here we present a total of 16,091 samples that were collected from May 2016 to February 2019 in 23 provinces and municipalities in China. We identify 2048 AIV-positive samples and perform next generation sequencing. AIV-positive rates (12.73%) from samples had decreased substantially since 2016, compared to that during 2014–2016 (26.90%). Additionally, H9N2 has replaced H5N6 and H7N9 as the dominant AIV subtype in both chickens and ducks. Notably, novel reassortants and variants continually emerged and disseminated in avian populations, including H7N3, H9N9, H9N6 and H5N6 variants. Importantly, almost all of the H9 AIVs and many H7N9 and H6N2 strains prefer human-type receptors, posing an increased risk for human infections. In summary, our nation-wide surveillance highlights substantial changes in the circulation of AIVs since 2016, which greatly impacts the prevention and control of AIVs in China and worldwide.

In this study, the authors present a genomic surveillance of avian influenza genomes sampled from live poultry markets in China. They report that a number of variants have emerged since 2016 that pose an increased risk to humans. They highlight the importance of continuous genome surveillance of circulating influenza strains.

Isolation of two novel reassortant H3N6 avian influenza viruses from long-distance migratory birds in Jiangxi Province, China

Two novel reassortant avian influenza A (H3N6) viruses were isolated from swan goose in Poyang Lake, Jiangxi Province, China, in 2014. Phylogenetic analyses indicated that these viruses are most likely derived from the Eurasian‐originated H3Ny (N3, N6, N8) and H5N6 viruses circulating among wild and domestic birds. It is noteworthy that H9N2 viruses have contributed PB1 gene to these novel H3N6 viruses. Our findings provide phylogenetic evidence to elucidate the ongoing viral reassortment in the wild bird population in southern China. Active surveillance of avian influenza viruses in Poyang Lake is warranted.

Production and identification of monoclonal antibodies and development of a sandwich ELISA for detection of the H3-subtype avian influenza virus antigen

The H3 subtype of avian influenza virus (AIV) is widespread in avian species and is frequently isolated in surveillance projects; thus, we have developed a more effective diagnostic approach of a monoclonal antibody (mAb)-based sandwich ELISA for the H3 AIV detection. First, we have produced the essential reagent of mAb against AIV H3 strains with the development of an mAb-Mouse immunization with a purified H3-subtype AIV strain and cell fusion to generate hybridoma cells. These cells were screened with hemagglutination inhibition (HI) tests, and optimal cells were subcloned. We chose a hybridoma cell line that steadily secreted a specific H3-subtype AIV mAb, designated 9F12, that belongs to the IgG1 subclass and has a K-type light chain. 9F12 was shown to bind specifically to the H3-subtype AIV antigen by both immunofluorescence assay and Western blot analysis. Finally, a 9F12-based sandwich ELISA was successfully developed and used to specifically test for this antigen. The sandwich ELISA conditions were optimized, and the specificity and sensitivity were validated. The results for clinical sample detection were consistent with viral isolation. Consequently, the 9F12-based sandwich ELISA is a specific, sensitive, robust, rapid and versatile diagnostic tool for H3-subtype AIV and provides a promising strategy for effective influenza virus prevention and control.

The evolution and genetic diversity of avian influenza A(H9N2) viruses in Cambodia, 2015 - 2016

Low pathogenic A(H9N2) subtype avian influenza viruses (AIVs) were originally detected in Cambodian poultry in 2013, and now circulate endemically. We sequenced and characterised 64 A(H9N2) AIVs detected in Cambodian poultry (chickens and ducks) from January 2015 to May 2016. All A(H9) viruses collected in 2015 and 2016 belonged to a new BJ/94-like h9-4.2.5 sub-lineage that emerged in the region during or after 2013, and was distinct to previously detected Cambodian viruses. Overall, there was a reduction of genetic diversity of H9N2 since 2013, however two genotypes were detected in circulation, P and V, with extensive reassortment between the viruses. Phylogenetic analysis showed a close relationship between A(H9N2) AIVs detected in Cambodian and Vietnamese poultry, highlighting cross-border trade/movement of live, domestic poultry between the countries. Wild birds may also play a role in A(H9N2) transmission in the region. Some genes of the Cambodian isolates frequently clustered with zoonotic A(H7N9), A(H9N2) and A(H10N8) viruses, suggesting a common ecology. Molecular analysis showed 100% of viruses contained the hemagglutinin (HA) Q226L substitution, which favours mammalian receptor type binding. All viruses were susceptible to the neuraminidase inhibitor antivirals; however, 41% contained the matrix (M2) S31N substitution associated with resistance to adamantanes. Overall, Cambodian A(H9N2) viruses possessed factors known to increase zoonotic potential, and therefore their evolution should be continually monitored.

Novel Reassortant Avian Influenza A(H3N8) Virus Isolated from a Wild Bird in Jiangxi, China

Here, we report the detection of a reassortant avian influenza A(H3N8) virus isolated from a wild bird in Poyang Lake, Jiangxi, China, in 2014. Phylogenetic analyses indicated that this virus is most likely derived from the Eurasian-origin H3Ny and HxN8 viruses and two strains endemic to China, namely, H5N1 and H5N6.

Here, we report the detection of a reassortant avian influenza A(H3N8) virus isolated from a wild bird in Poyang Lake, Jiangxi, China, in 2014. Phylogenetic analyses indicated that this virus is most likely derived from the Eurasian-origin H3Ny and HxN8 viruses and two strains endemic to China, namely, H5N1 and H5N6.

A study of the relationship between human infection with avian influenza a (H5N6) and environmental avian influenza viruses in Fujian, China

BACKGROUND

Avian influenza A (H5N6) virus poses a great threat to the human health since it is capable to cross the species barrier and infect humans. Although human infections are believed to largely originate from poultry contaminations, the transmissibility is unclear and only limited information was available on poultry environment contaminations, especially in Fujian Province.

METHODS

A total of 4901 environmental samples were collected and tested for Avian Influenza Virus (AIV) from six cities in Fujian Province through the Fujian Influenza Surveillance System from 2013 to 2017. Two patient-related samples were taken from Fujian's first confirmed H5N6 human case and his backyard chicken feces in 2017. Chi-square test or Fisher's exact probability test was used to compare the AIV and the viral subtype positive rates among samples from different Surveillance cities, surveillance sites, sample types, and seasons. Phylogenetic tree analysis and molecular analysis were conducted to track the viral transmission route of the human infection and to map out the evolutions of H5N6 in Fujian.

RESULTS

The overall positive rate of the H5 subtype AIVs was 4.24% (208/4903). There were distinctive differences (p < 0.05) in the positive rates in samples from different cities, sample sites, sample types and seasons. The viruses from the patient and his backyard chicken feces shared high homologies (99.9-100%) in all the eight gene segments. Phylogenetic trees also showed that these two H5N6 viruses were closely related to each other, and were classified into the same genetic clade 2.3.4.4 with another six H5N6 isolates from the environmental samples. The patient's H5N6 virus carried genes from H6N6, H5N8 and H5N6 viruses originated from different areas. The R294K or N294S substitution was not detected in the neuraminidase (NA). The S31 N substitution in the matrix2 (M2) gene was detected but only in one strain from the environmental samples.

CONCLUSIONS

The H5 subtype of AIVs has started circulating in the poultry environments in Fujian Province. The patient's viral strain originated from the chicken feces in his backyard. Genetic reassortment in H5N6 viruses in Fujian Province was indicated. The H5N6 viruses currently circulating in Fujian Province were still commonly sensitive to Oseltamivir and Zanamivir, but the resistance against Amantadine has emerged.

Avian influenza in the Greater Mekong Subregion, 2003-2018

The persistent circulation of avian influenza viruses (AIVs) is an ongoing problem for many countries in South East Asia, causing large economic losses to both the agricultural and health sectors. This review analyses AIV diversity, evolution and the risk of AIV emergence in humans in countries of the Greater Mekong Subregion (GMS): Cambodia, Laos, Myanmar, Thailand and Vietnam (excluding China). The analysis was based on AIV sequencing data, serological studies, published journal articles and AIV outbreak reports available from January 2003 to December 2018. All countries of the GMS have suffered losses due repeated outbreaks of highly pathogenic (HP) H5N1 that has also caused human cases in all GMS countries. In Laos, Myanmar and Vietnam AIV outbreaks in domestic poultry have also been caused by clade 2.3.4.4 H5N6. A diverse range of low pathogenic AIVs (H1-H12) have been detected in poultry and wild bird species, though surveillance for and characterization of these subtypes is limited. Subtype H3, H4, H6 and H11 viruses have been detected over prolonged periods; whilst H1, H2, H7, H8, H10 and H12 viruses have only been detected transiently. H9 AIVs circulate endemically in Cambodia and Vietnam with seroprevalence data indicating human exposure to H9 AIVs in Cambodia, Thailand and Vietnam. As surveillance studies focus heavily on the detection of H5 AIVs in domestic poultry further research is needed to understand the true level of AIV diversity and the risk AIVs pose to humans in the GMS.

Simultaneous Differentiation of the N1 to N9 Neuraminidase Subtypes of Avian Influenza Virus by a GeXP Analyzer-Based Multiplex Reverse Transcription PCR Assay

To date, nine neuraminidase (NA) subtypes of avian influenza virus (AIV) have been identified in poultry and wild birds. Rapid and effective methods for differentiating these nine NA subtypes are needed. We developed and validated a rapid, sensitive, and robust method utilizing a GeXP analyzer-based multiplex RT-PCR assay and capillary electrophoresis for the simultaneous differentiation of the N1 to N9 subtypes in a single-tube reaction. Ten pairs of primers-nine subtype-specific pairs and one pan-AIV pair-were screened and used to establish the GeXP multiplex RT-PCR assay. A single subtype was detected using the developed GeXP assay; the N1 to N9 AIV subtypes individually generated two target peaks: the NA subtype-specific peak and the general AIV peak. Different concentrations of multiplexed subtypes were tested with this GeXP assay and the peaks of the corresponding NA subtypes were generated, suggesting that this GeXP assay is useful for identifying NA subtypes in mixed samples. Moreover, no peaks were generated for other important avian viruses, indicating negative results and validating the lack of cross-reactions between AIV subtypes and other avian pathogens. RNA templates synthesized through in vitro transcription were used to analyze the sensitivity of the assay; the limit of detection was 100 copies per reaction mixture. The results obtained from clinical samples using this GeXP method were consistent with the results of the neuraminidase inhibition (NI) test, and the ability of the GeXP assay to identify mixed infections was superior to amplicon sequencing of isolated viruses. In conclusion, this GeXP assay is proposed as a specific, sensitive, rapid, high-throughput, and versatile diagnostic tool for nine NA subtypes of AIV.

Computational identification of physicochemical signatures for host tropism of influenza A virus

Avian influenza viruses from migratory birds have managed to cross host species barriers and infected various hosts like human and swine. Epidemics and pandemics might occur when influenza viruses are adapted to humans, causing deaths and enormous economic loss. Receptor-binding specificity of the virus is one of the key factors for the transmission of influenza viruses across species. The determination of host tropism and understanding of molecular properties would help identify the mechanism why zoonotic influenza viruses can cross species barrier and infect humans. In this study, we have constructed computational models for host tropism prediction on human-adapted subtypes of influenza HA proteins using random forest. The feature vectors of the prediction models were generated based on seven physicochemical properties of amino acids from influenza sequences of three major hosts. Feature aggregation and associative rules were further applied to select top 20 features and extract host-associated physicochemical signatures on the combined model of nonspecific subtypes. The prediction model achieved high performance ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mtext>Accuracy</mml:mtext><mml:mo>=</mml:mo><mml:mn>0</mml:mn><mml:mo>.</mml:mo><mml:mn>9</mml:mn><mml:mn>4</mml:mn><mml:mn>8</mml:mn></mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mtext>Precision</mml:mtext><mml:mo>=</mml:mo><mml:mn>0</mml:mn><mml:mo>.</mml:mo><mml:mn>9</mml:mn><mml:mn>5</mml:mn><mml:mn>4</mml:mn></mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mtext>MCC</mml:mtext><mml:mo>=</mml:mo><mml:mn>0</mml:mn><mml:mo>.</mml:mo><mml:mn>9</mml:mn><mml:mn>2</mml:mn><mml:mn>2</mml:mn></mml:math> ). Support and confidence rates were calculated for the host class-association rules. The results indicated that secondary structure and normalized Van der Waals volume were identified as more important physicochemical signatures in determining the host tropism.

Zoonotic Potential of Influenza A Viruses: A Comprehensive Overview

Influenza A viruses (IAVs) possess a great zoonotic potential as they are able to infect different avian and mammalian animal hosts, from which they can be transmitted to humans. This is based on the ability of IAV to gradually change their genome by mutation or even reassemble their genome segments during co-infection of the host cell with different IAV strains, resulting in a high genetic diversity. Variants of circulating or newly emerging IAVs continue to trigger global health threats annually for both humans and animals. Here, we provide an introduction on IAVs, highlighting the mechanisms of viral evolution, the host spectrum, and the animal/human interface. Pathogenicity determinants of IAVs in mammals, with special emphasis on newly emerging IAVs with pandemic potential, are discussed. Finally, an overview is provided on various approaches for the prevention of human IAV infections.

Molecular epidemiological survey and complete genomic phylogenetic analysis of H6 subtype avian influenza viruses in poultry in China from 2011 to 2016

To investigate the prevalence and evolution of the H6 subtype avian influenza viruses (AIVs) circulating in poultry in China from 2011 to 2016, 11 molecular epidemiological surveys was performed in this study. In total, 893 H6 subtype viral strains were isolated from 67,639 swab samples and 360 environmental samples. From these strains, 35 representative strains were selected and their whole genomic sequences determined. According to a phylogenetic analysis and molecular characterization, all 35 viral strains belonged to the Eurasian avian lineage. All of them were categorized as 'low pathogenic' and a few strains had some bioinformatical mutations. This epidemiological survey shows that the prevalence of H6 subtype AIVs increased from 2012 to 2016 in China, and suggests that infections by H6 subtype AIVs in China has increased in recent years.

Characterization of an Avian Influenza Virus H9N2 Strain Isolated from Dove in Southern China

We report here the complete genome sequence of strain H9N2, an avian influenza virus (AIV) isolated from dove in Guangxi, China. Phylogenetic analysis showed that it was a novel reassortant AIV derived from chicken, duck, and wild bird. This finding provides useful information for understanding the H9N2 subtype of AIV circulating in southern China.