Panorama phylogenetic diversity and distribution of type A influenza viruses based on their six internal gene sequences

Eliciting a single amino acid change by vaccination generates antibody protection against group 1 and group 2 influenza A viruses

Broadly neutralizing antibodies (bnAbs) targeting the hemagglutinin (HA) stem of influenza A viruses (IAVs) tend to be effective against either group 1 or group 2 viral diversity. In rarer cases, intergroup protective bnAbs can be generated by human antibody paratopes that accommodate the conserved glycan differences between the group 1 and group 2 stems. We applied germline-engaging nanoparticle immunogens to elicit a class of cross-group bnAbs from physiological precursor frequency within a humanized mouse model. Cross-group protection depended on the presence of the human bnAb precursors within the B cell repertoire, and the vaccine-expanded antibodies enriched for an N55T substitution in the CDRH2 loop, a hallmark of the bnAb class. Structurally, this single mutation introduced a flexible fulcrum to accommodate glycosylation differences and could alone enable cross-group protection. Thus, broad IAV immunity can be expanded from the germline repertoire via minimal antigenic input and an exceptionally simple antibody development pathway.

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.

Investigation of antibiotic resistance determinants and virulence factors of uropathogenic Escherichia coli

Multidrug-resistant (MDR) uropathogenic Escherichia coli (UPEC) are prevalent throughout the world resulting in a major public health burden. In this research, we isolated and identified 28 MDR UPEC from one university hospital in China, investigated MDR and pathogenic mechanisms by PCR, including 55 antibiotic resistance determinants (ARDs) genes, 13 genetic markers of mobile genetic elements (MGEs) and 6 virulence factors (VFs) genes. In these isolates, we identified 23 ARDs genes and 6 genetic markers of MGEs that played a key role in MDR phenotypes. In addition, we found 2 VFs genes, hofQ and ompT, which could be associated with pathogenicity and invasiveness of these strains in urinary tract infections (UTIs).

Detection of a Reassortant H9N2 Avian Influenza Virus with Intercontinental Gene Segments in a Resident Australian Chestnut Teal

The present study reports the genetic characterization of a low-pathogenicity H9N2 avian influenza virus, initially from a pool and subsequently from individual faecal samples collected from Chestnut teals (Anas castanea) in southeastern Australia. Phylogenetic analyses of six full gene segments and two partial gene segments obtained from next-generation sequencing showed that this avian influenza virus, A/Chestnut teal/Australia/CT08.18/12952/2018 (H9N2), was a typical, low-pathogenicity, Eurasian aquatic bird lineage H9N2 virus, albeit containing the North American lineage nucleoprotein (NP) gene segment detected previously in Australian wild birds. This is the first report of a H9N2 avian influenza virus in resident wild birds in Australia, and although not in itself a cause of concern, is a clear indication of spillover and likely reassortment of influenza viruses between migratory and resident birds, and an indication that any lineage could potentially be introduced in this way.

Diversity and distribution of type A influenza viruses: an updated panorama analysis based on protein sequences

Background

Type A influenza viruses (IAVs) cause significant infections in humans and multiple species of animals including pigs, horses, birds, dogs and some marine animals. They are of complicated phylogenetic diversity and distribution, and analysis of their phylogenetic diversity and distribution from a panorama view has not been updated for multiple years.

Methods

139,872 protein sequences of IAVs from GenBank were selected, and they were aligned and phylogenetically analyzed using the software tool MEGA 7.0. Lineages and subordinate lineages were classified according to the topology of the phylogenetic trees and the host, temporal and spatial distribution of the viruses, and designated using a novel universal nomenclature system.

Results

Large phylogenetic trees of the two external viral genes (HA and NA) and six internal genes (PB2, PB1, PA, NP, MP and NS) were constructed, and the diversity and the host, temporal and spatial distribution of these genes were calculated and statistically analyzed. Various features regarding the diversity and distribution of IAVs were confirmed, revised or added through this study, as compared with previous reports. Lineages and subordinate lineages were classified and designated for each of the genes based on the updated panorama views.

Conclusions

The panorama views of phylogenetic diversity and distribution of IAVs and their nomenclature system were updated and assumed to be of significance for studies and communication of IAVs.

Electronic supplementary material

The online version of this article (10.1186/s12985-019-1188-7) contains supplementary material, which is available to authorized users.

Prediction of Influenza A virus infections in humans using an Artificial Neural Network learning approach

The Influenza type A virus can be considered as one of the most severe viruses that can infect multiple species with often fatal consequences to the hosts. The Haemagglutinin (HA) gene of the virus has the potential to be a target for antiviral drug development realised through accurate identification of its sub-types and possible the targeted hosts. In this paper, to accurately predict if an Influenza type A virus has the capability to infect human hosts, by using only the HA gene, is therefore developed and tested. The predictive model follows three main steps; (i) decoding the protein sequences into numerical signals using EIIP amino acid scale, (ii) analysing these sequences by using Discrete Fourier Transform (DFT) and extracting DFT-based features, (iii) using a predictive model, based on Artificial Neural Networks and using the features generated by DFT. In this analysis, from the Influenza Research Database, 30724, 18236 and 8157 HA protein sequences were collected for Human, Avian and Swine respectively. Given this set of the proteins, the proposed method yielded 97.36% (± 0.04%), 97.26% (± 0.26%), 0.978 (± 0.004), 0.963 (± 0.005) and 0.945 (±0.005) for the training accuracy validation accuracy, precision, recall and Mathews Correlation Coefficient (MCC) respectively, based on a 10-fold cross-validation. The classification model generated by using one of the largest dataset, if not the largest, yields promising results that could lead to early detection of such species and help develop precautionary measurements for possible human infections.

Genetic variation and co-evolutionary relationship of RNA polymerase complex segments in influenza A viruses

The RNA polymerase complex (RNApc) in influenza A viruses (IVs) is composed of the PB2, PB1 and PA subunits, which are encoded by the three longest genome segments (Seg1-3) and are responsible for the replication of vRNAs and transcription of viral mRNAs. However, the co-evolutionary relationships of the three segments from the known 126 subtypes IVs are unclear. In this study, we performed a detailed analysis based on a total number of 121,191 nucleotide sequences. Three segment sequences were aligned before the repeated, incomplete and mixed sequences were removed for homologous and phylogenetic analyses. Subsequently, the estimated substitution rates and TMRCAs (Times for Most Recent Common Ancestor) were calculated by 175 representative IVs. Tracing the cladistic distribution of three segments from these IVs, co-evolutionary patterns and trajectories could be inferred. The further correlation analysis of six internal protein coding segments reflect the RNApc segments have the closer correlation than others during continuous reassortments. This global approach facilitates the establishment of a fast antiviral strategy and monitoring of viral variation.

N-glycan profiles in H9N2 avian influenza viruses from chicken eggs and human embryonic lung fibroblast cells

N-glycosylation can affect the host specificity, virulence and infectivity of influenza A viruses (IAVs). In this study, the distribution and evolution of N-glycosylation sites in the hemagglutinin (HA) and neuraminidase (NA) of H9N2 virus were explored using phylogenetic analysis. Then, one strain of the H9N2 subtypes was proliferated in the embryonated chicken eggs (ECE) and human embryonic lung fibroblast cells (MRC-5) system. The proliferated viral N-glycan profiles were analyzed by a glycomic method that combined the lectin microarray and MALDI-TOF/TOF-MS. As a result, HA and NA of H9N2 viruses prossess six and five highly conserved N-glycosylation sites, respectively. Sixteen lectins (e.g., MAL-II, SNA and UEA-I) had increased expression levels of the glycan structures in the MRC-5 compared with the ECE system; however, 6 lectins (e.g., PHA-E, PSA and DSA) had contrasting results. Eleven glycans from the ECE system and 13 glycans from the MRC-5 system were identified. Our results showed that the Fucα-1,6GlcNAc(core fucose) structure was increased, and pentaantennary N-glycans were only observed in the ECE system. The SAα2-3/6Gal structures were highly expressed and Fucα1-2Galβ1-4GlcNAc structures were only observed in the MRC-5 system. We conclude that the existing SAα2-3/6Gal sialoglycans make the offspring of the H9N2 virus prefer entially attach to each other, which decreases the virulence. Alterations in the glycosylation sites for the evolution and role of IAVs have been widely described; however, little is known about the exact glycan structures for the same influenza strain from different hosts. Our findings may provide a novel way for further discussing the molecular mechanism of the viral transmission and virulence associated with viral glycosylation in avian and human hosts as well as vital information for designing a vaccine against influenza and other human viruses.

Assessing parallel gene histories in viral genomes

BACKGROUND

The increasing abundance of sequence data has exacerbated a long known problem: gene trees and species trees for the same terminal taxa are often incongruent. Indeed, genes within a genome have not all followed the same evolutionary path due to events such as incomplete lineage sorting, horizontal gene transfer, gene duplication and deletion, or recombination. Considering conflicts between gene trees as an obstacle, numerous methods have been developed to deal with these incongruences and to reconstruct consensus evolutionary histories of species despite the heterogeneity in the history of their genes. However, inconsistencies can also be seen as a source of information about the specific evolutionary processes that have shaped genomes.

RESULTS

The goal of the approach here proposed is to exploit this conflicting information: we have compiled eleven variables describing phylogenetic relationships and evolutionary pressures and submitted them to dimensionality reduction techniques to identify genes with similar evolutionary histories. To illustrate the applicability of the method, we have chosen two viral datasets, namely papillomaviruses and Turnip mosaic virus (TuMV) isolates, largely dissimilar in genome, evolutionary distance and biology. Our method pinpoints viral genes with common evolutionary patterns. In the case of papillomaviruses, gene clusters match well our knowledge on viral biology and life cycle, illustrating the potential of our approach. For the less known TuMV, our results trigger new hypotheses about viral evolution and gene interaction.

CONCLUSIONS

The approach here presented allows turning phylogenetic inconsistencies into evolutionary information, detecting gene assemblies with similar histories, and could be a powerful tool for comparative pathogenomics.

Phylogenetic Analysis of Hemagglutinin Genes of H9N2 Avian Influenza Viruses Isolated from Chickens in Shandong, China, between 1998 and 2013

Since H9N2 avian influenza virus (AIV) was first isolated in Guangdong province of China, the virus has been circulating in chicken flocks in mainland China. However, a systematic phylogenetic analysis of H9N2 AIV from chickens in Shandong of China has not been conducted. Based on hemagglutinin (HA) gene sequences of H9N2 AIVs isolated from chickens in Shandong of China between 1998 and 2013, genetic evolution of 35 HA gene sequences was systematically analyzed in this study. Our findings showed that the majority of H9N2 AIVs (21 out of 35) belonged to the lineage h9.4.2.5. Most of isolates (33 out of 35) had a PSRSSR↓GLF motif in HA cleavage site. Importantly, 29 out of these 35 isolates had an amino acid exchange (Q226L) in the receptor-binding site. The substitution showed that H9N2 AIVs had the potential affinity to bind to human-like receptor. The currently prevalent H9N2 AIVs in Shandong belonged to the lineage h9.4.2.5 which are different from the vaccine strain SS/94 clade h9.4.2.3. Therefore, the long-term surveillance of H9N2 AIVs is of significance to combat the possible H9N2 AIV outbreaks.

Comparison of three media for transport and storage of the samples collected for detection of avian influenza virus

Detection of avian influenza viruses (AIVs) is important for diagnosis, surveillance and control of avian influenza which is of great economic and public health significance. Proper transport and storage of samples is critical for the detection when the samples cannot be detected immediately. As recommended by some international or national authoritative entities and some publications, phosphate buffered saline (PBS), PBS-glycerol and brain heart infusion broth (BHIB) are frequently used for transport and storage of the samples collected for detection of AIVs worldwide. In this study, we compared these three media for transport and storage of simulated and authentic swab and feces samples collected for detection of AIVs using virus isolation and reverse transcription-PCR. The results suggest that PBS-glycerol is superior to PBS and BHIB as the sample transport and storage media. The results also suggest that the samples collected for detection of AIVs should be detected as soon as possible because the virus concentration of the samples may decline rapidly during storage within days at 4 or -20°C.

Evolutionary dynamics of influenza A nucleoprotein (NP) lineages revealed by large-scale sequence analyses

Influenza A viral nucleoprotein (NP) plays a critical role in virus replication and host adaptation, however, the underlying molecular evolutionary dynamics of NP lineages are less well-understood. In this study, large-scale analyses of 5094 NP nucleotide sequences revealed eight distinct evolutionary lineages, including three host-specific lineages (human, classical swine and equine), two cross-host lineages (Eurasian avian-like swine and swine-origin human pandemic H1N1 2009) and three geographically isolated avian lineages (Eurasian, North American and Oceanian). The average nucleotide substitution rate of the NP lineages was estimated to be 2.4 × 10(-3) substitutions per site per year, with the highest value observed in pandemic H1N1 2009 (3.4 × 10(-3)) and the lowest in equine (0.9 × 10(-3)). The estimated time of most recent common ancestor (TMRCA) for each lineage demonstrated that the earliest human lineage was derived around 1906, and the latest pandemic H1N1 2009 lineage dated back to December 17, 2008. A marked time gap was found between the times when the viruses emerged and were first sampled, suggesting the crucial role for long-term surveillance of newly emerging viruses. The selection analyses showed that human lineage had six positive selection sites, whereas pandemic H1N1 2009, classical swine, Eurasian avian and Eurasian swine had only one or two sites. Protein structure analyses revealed several positive selection sites located in epitope regions or host adaptation regions, indicating strong adaptation to host immune system pressures in influenza viruses. Along with previous studies, this study provides new insights into the evolutionary dynamics of influenza A NP lineages. Further lineage analyses of other gene segments will allow better understanding of influenza A virus evolution and assist in the improvement of global influenza surveillance.

PhyloMap: an algorithm for visualizing relationships of large sequence data sets and its application to the influenza A virus genome

Background

Results of phylogenetic analysis are often visualized as phylogenetic trees. Such a tree can typically only include up to a few hundred sequences. When more than a few thousand sequences are to be included, analyzing the phylogenetic relationships among them becomes a challenging task. The recent frequent outbreaks of influenza A viruses have resulted in the rapid accumulation of corresponding genome sequences. Currently, there are more than 7500 influenza A virus genomes in the database. There are no efficient ways of representing this huge data set as a whole, thus preventing a further understanding of the diversity of the influenza A virus genome.

Results

Here we present a new algorithm, "PhyloMap", which combines ordination, vector quantization, and phylogenetic tree construction to give an elegant representation of a large sequence data set. The use of PhyloMap on influenza A virus genome sequences reveals the phylogenetic relationships of the internal genes that cannot be seen when only a subset of sequences are analyzed.

Conclusions

The application of PhyloMap to influenza A virus genome data shows that it is a robust algorithm for analyzing large sequence data sets. It utilizes the entire data set, minimizes bias, and provides intuitive visualization. PhyloMap is implemented in JAVA, and the source code is freely available at http://www.biochem.uni-luebeck.de/public/software/phylomap.html

A complete analysis of HA and NA genes of influenza A viruses

BACKGROUND

More and more nucleotide sequences of type A influenza virus are available in public databases. Although these sequences have been the focus of many molecular epidemiological and phylogenetic analyses, most studies only deal with a few representative sequences. In this paper, we present a complete analysis of all Haemagglutinin (HA) and Neuraminidase (NA) gene sequences available to allow large scale analyses of the evolution and epidemiology of type A influenza.

METHODOLOGY/PRINCIPAL FINDINGS

This paper describes an analysis and complete classification of all HA and NA gene sequences available in public databases using multivariate and phylogenetic methods.

CONCLUSIONS/SIGNIFICANCE

We analyzed 18,975 HA sequences and divided them into 280 subgroups according to multivariate and phylogenetic analyses. Similarly, we divided 11,362 NA sequences into 202 subgroups. Compared to previous analyses, this work is more detailed and comprehensive, especially for the bigger datasets. Therefore, it can be used to show the full and complex phylogenetic diversity and provides a framework for studying the molecular evolution and epidemiology of type A influenza virus. For more than 85% of type A influenza HA and NA sequences into GenBank, they are categorized in one unambiguous and unique group. Therefore, our results are a kind of genetic and phylogenetic annotation for influenza HA and NA sequences. In addition, sequences of swine influenza viruses come from 56 HA and 45 NA subgroups. Most of these subgroups also include viruses from other hosts indicating cross species transmission of the viruses between pigs and other hosts. Furthermore, the phylogenetic diversity of swine influenza viruses from Eurasia is greater than that of North American strains and both of them are becoming more diverse. Apart from viruses from human, pigs, birds and horses, viruses from other species show very low phylogenetic diversity. This might indicate that viruses have not become established in these species. Based on current evidence, there is no simple pattern of inter-hemisphere transmission of avian influenza viruses and it appears to happen sporadically. However, for H6 subtype avian influenza viruses, such transmissions might have happened very frequently and multiple and bidirectional transmission events might exist.

Emergency surveillance of influenza during 2009 in the Chinese city of Qingdao

Please cite this paper as: Wang et al. (2010) Emergency surveillance of influenza during 2009 in the Chinese city of Qingdao. Influenza and Other Respiratory Viruses 5(1), 53–59.

Background  In April, 2009, a new influenza pandemic caused by a swine‐origin H1N1 subtype influenza virus was imminent. We thereby carried out an emergency surveillance study in a Chinese city of Qingdao.

Methods  Pharyngeal swab samples were collected from four targeted groups and tested by reverse‐transcription polymerase chain reaction. Each laboratory‐confirmed pandemic H1N1 case or cluster was investigated, and the hemagglutinin genes of some of the viruses were sequenced and analyzed.

Results  A total of 140 pandemic H1N1 cases including 92 from 7 clusters were identified in the four targeted groups. None of them developed into severe infections. Meanwhile, 103 cases of seasonal influenza (98 H3N2 and 5 H1N1) and 10 clusters of seasonal H3N2 influenza were also identified. Among them, 38 pandemic H1N1 and two seasonal H3N2 influenza cases were air travellers, suggesting that air travel facilitates the spread of pandemic and seasonal influenza even in the northern hemisphere summer. In addition, it was found that pandemic H1N1 and seasonal H3N2 influenza viruses co‐circulated in two clusters. No significant mutations were found in the hemagglutinin gene sequences of pandemic H1N1 viruses, but the seasonal H3N2 influenza viruses have become genetically distinguishable from those circulating in 2007–2008.

Understanding the Influenza A H1N1 2009 Pandemic

A new strain of Influenza A virus, with quadruple segment translocation in its RNA, caused an outbreak of human infection in April 2009 in USA and Mexico. It was classified as Influenza A H1N1 2009. The genetic material originates from three different species: human, avian and swine. By June 2009, the World Health Organization (WHO) had classified this strain as a pandemic virus, making it the first pandemic in 40 years. Influenza A H1N1 2009 is transmitted by respiratory droplets; the transmissibility of this strain is higher than other influenza strains which made infection control difficult. The majority of cases of H1N1 2009 were mild and self limiting, but some people developed complications and others died. Most laboratory tests are insensitive except the polymerase chain reaction (PCR) which is expensive and labour intensive. The Influenza A H1N1 2009 virus is sensitive to neuraminidase inhibitors (oseltamivir and zanamivir), but some isolates resistant to oseltamivir have been reported. A vaccine against the new pandemic strain was available by mid-September 2009 with very good immunogenicity and safety profile. Surveillance is very important at all stages of any pandemic to detect and monitor the trend of viral infections and to prevent the occurrence of future pandemics. The aim of this review is to understand pandemic influenza viruses, and what strategies can be used for surveillance, mitigation and control.

Genetic variation at a single locus and age of onset for Alzheimer's disease

This perspective article provides an opportunity to explain a new genetic finding for late-onset Alzheimer's disease (LOAD). It is specifically written for physicians and scientists who are interested in LOAD, but it may be relevant to those interested in identifying susceptibility variants for other complex diseases. The significant finding discussed here is that a variable-length, deoxythymidine homopolymer (poly-T) within intron 6 of the TOMM40 gene is associated with the age of onset of LOAD [Roses AD, Lutz MW, Amrine-Madsen H, Saunders AM, Crenshaw DG, Sundseth SS, et al. A TOMM40 variable-length polymorphism predicts the age of late-onset Alzheimer's disease. Pharmacogenomics J 2009 December 22;[Epublication ahead of print]. This result was obtained with a phylogenetic study of the genetic polymorphisms that reside within the linkage disequilibrium (LD) block that contains the TOMM40, APOE, and APOC1 genes from patients with LOAD and age-matched subjects without disease. Although the data will have diagnostic, prognostic, and therapeutic strategy implications, this perspective is meant to place the inheritance pattern for this "complex" human disease into context, and to highlight the potential utility of applying phylogenetic tools to the study of the genetics of complex diseases.

Molecular character of influenza A/H1N1 2009: Implications for spread and control

The world is experiencing a pandemic of influenza that emerged in March 2009, due to a novel strain designated influenza A/H1N1 2009. This strain is closest in molecular sequence to swine influenza viruses, but differs from all previously known influenza by a minimum of 6.1%, and from prior "seasonal" H1N1 by 27.2%, giving it great potential for widespread human infection. While spread into India was delayed for two months by an aggressive interdiction program, since 1 August 2009 most cases in India have been indigenous. H1N1 2009 has differentially struck younger patients who are naïve susceptibles to its antigenic subtype, while sparing those >60 who have crossreactive antibody from prior experience with influenza decades ago and the 1977 "swine flu" vaccine distributed in the United States. It also appears to more severely affect pregnant women. It emanated from a single source in central Mexico, but its precise geographical and circumstantial origins, from either Eurasia or the Americas, remain uncertain. While currently a mild pandemic by the standard of past pandemics, the seriousness of H1N1 2009 especially among children should not be underestimated. There is potential for the virus, which continues to adapt to humans, to change over time into a more severe etiologic agent by any of several foreseeable mutations. Mass acceptance of the novel H1N1 2009 vaccine worldwide will be essential to its control. Having spread globally in a few months, affecting millions of people, it is likely to remain circulating in the human population for a decade or more.

From where did the 2009 'swine-origin' influenza A virus (H1N1) emerge?

The swine-origin influenza A (H1N1) virus that appeared in 2009 and was first found in human beings in Mexico, is a reassortant with at least three parents. Six of the genes are closest in sequence to those of H1N2 'triple-reassortant' influenza viruses isolated from pigs in North America around 1999-2000. Its other two genes are from different Eurasian 'avian-like' viruses of pigs; the NA gene is closest to H1N1 viruses isolated in Europe in 1991-1993, and the MP gene is closest to H3N2 viruses isolated in Asia in 1999-2000. The sequences of these genes do not directly reveal the immediate source of the virus as the closest were from isolates collected more than a decade before the human pandemic started. The three parents of the virus may have been assembled in one place by natural means, such as by migrating birds, however the consistent link with pig viruses suggests that human activity was involved. We discuss a published suggestion that unsampled pig herds, the intercontinental live pig trade, together with porous quarantine barriers, generated the reassortant. We contrast that suggestion with the possibility that laboratory errors involving the sharing of virus isolates and cultured cells, or perhaps vaccine production, may have been involved. Gene sequences from isolates that bridge the time and phylogenetic gap between the new virus and its parents will distinguish between these possibilities, and we suggest where they should be sought. It is important that the source of the new virus be found if we wish to avoid future pandemics rather than just trying to minimize the consequences after they have emerged. Influenza virus is a very significant zoonotic pathogen. Public confidence in influenza research, and the agribusinesses that are based on influenza's many hosts, has been eroded by several recent events involving the virus. Measures that might restore confidence include establishing a unified international administrative framework coordinating surveillance, research and commercial work with this virus, and maintaining a registry of all influenza isolates.