Analysis of the Evolution of Pandemic Influenza A(H1N1) Virus Neuraminidase Reveals Entanglement of Different Phenotypic Characteristics

ABSTRACT The influenza A virus (IAV) neuraminidase (NA) is essential for virion release from cells and decoy receptors and an important target of antiviral drugs and antibodies. Adaptation to a new host sialome and escape from the host immune system are forces driving the selection of mutations in the NA gene. Phylogenetic analysis shows that until 2015, 16 amino acid substitutions in NA became fixed in the virus population after introduction in the human population of the pandemic IAV H1N1 (H1N1pdm09) in 2009. The accumulative effect of these substitutions, in the order in which they appeared, was analyzed using recombinant proteins and viruses in combination with different functional assays. The results indicate that NA activity did not evolve to a single optimum but rather fluctuated within a certain bandwidth. Furthermore, antigenic and enzymatic properties of NA were intertwined, with several residues affecting multiple properties. For example, the substitution K432E in the second sialic acid binding site, next to the catalytic site, was shown to affect catalytic activity, substrate specificity, and the pH optimum for maximum activity. This substitution also altered antigenicity of NA, which may explain its selection. We propose that the entanglement of NA phenotypes may be an important determining factor in the evolution of NA. IMPORTANCE Since its emergence in 2009, the pandemic H1N1 influenza A virus (IAV) has caused significant disease and mortality in humans. IAVs contain two envelope glycoproteins, the receptor-binding hemagglutinin (HA) and the receptor-destroying neuraminidase (NA). NA is essential for virion release from cells and decoy receptors, is an important target of antiviral drugs, and is increasingly being recognized as an important vaccine antigen. Not much is known, however, about the evolution of this protein upon the emergence of the novel pandemic H1N1 virus, with respect to its enzymatic activity and antigenicity. By reconstructing the evolutionary path of NA, we show that antigenic and enzymatic properties of NA are intertwined, with several residues affecting multiple properties. Understanding the entanglement of NA phenotypes will lead to better comprehension of IAV evolution and may help the development of NA-based vaccines.

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Pandemic H1N1 2009 Influenza A Virus Induces Weak Cytokine Responses in Human Macrophages and Dendritic Cells and Is Highly Sensitive to the Antiviral Actions of Interferons

Journal of Virology ◽

10.1128/jvi.01619-09 ◽

2009 ◽

Vol 84 (3) ◽

pp. 1414-1422 ◽

Cited By ~ 110

Author(s):

Pamela Österlund ◽

Jaana Pirhonen ◽

Niina Ikonen ◽

Esa Rönkkö ◽

Mari Strengell ◽

...

Keyword(s):

Dendritic Cells ◽

Influenza A Virus ◽

Influenza A ◽

H1n1 Virus ◽

Influenza Viruses ◽

Type I ◽

Pandemic H1n1 ◽

Pandemic Virus ◽

Highly Sensitive ◽

Influenza A H1n1

ABSTRACT In less than 3 months after the first cases of swine origin 2009 influenza A (H1N1) virus infections were reported from Mexico, WHO declared a pandemic. The pandemic virus is antigenically distinct from seasonal influenza viruses, and the majority of human population lacks immunity against this virus. We have studied the activation of innate immune responses in pandemic virus-infected human monocyte-derived dendritic cells (DC) and macrophages. Pandemic A/Finland/553/2009 virus, representing a typical North American/European lineage virus, replicated very well in these cells. The pandemic virus, as well as the seasonal A/Brisbane/59/07 (H1N1) and A/New Caledonia/20/99 (H1N1) viruses, induced type I (alpha/beta interferon [IFN-α/β]) and type III (IFN-λ1 to -λ3) IFN, CXCL10, and tumor necrosis factor alpha (TNF-α) gene expression weakly in DCs. Mouse-adapted A/WSN/33 (H1N1) and human A/Udorn/72 (H3N2) viruses, instead, induced efficiently the expression of antiviral and proinflammatory genes. Both IFN-α and IFN-β inhibited the replication of the pandemic (H1N1) virus. The potential of IFN-λ3 to inhibit viral replication was lower than that of type I IFNs. However, the pandemic virus was more sensitive to the antiviral IFN-λ3 than the seasonal A/Brisbane/59/07 (H1N1) virus. The present study demonstrates that the novel pandemic (H1N1) influenza A virus can readily replicate in human primary DCs and macrophages and efficiently avoid the activation of innate antiviral responses. It is, however, highly sensitive to the antiviral actions of IFNs, which may provide us an additional means to treat severe cases of infection especially if significant drug resistance emerges.

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Rapid Multiplex Reverse Transcription-PCR Typing of Influenza A and B Virus, and Subtyping of Influenza A Virus into H1, 2, 3, 5, 7, 9, N1 (Human), N1 (Animal), N2, and N7, Including Typing of Novel Swine Origin Influenza A (H1N1) Virus, during the 2009 Outbreak in Milwaukee, Wisconsin

Journal of Clinical Microbiology ◽

10.1128/jcm.00998-09 ◽

2009 ◽

Vol 47 (9) ◽

pp. 2772-2778 ◽

Cited By ~ 65

Author(s):

J. He ◽

M. E. Bose ◽

E. T. Beck ◽

J. Fan ◽

S. Tiwari ◽

...

Keyword(s):

Influenza A Virus ◽

Reverse Transcription ◽

Influenza A ◽

H1n1 Virus ◽

Reverse Transcription Pcr ◽

Influenza A H1n1 ◽

B Virus

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Recycling of H1N1 influenza A virus in man — a haemagglutinin antibody study

Journal of Hygiene ◽

10.1017/s0022172400029028 ◽

1993 ◽

Vol 90 (3) ◽

pp. 397-402 ◽

Cited By ~ 15

Author(s):

N. Masurel ◽

R. A. Heijtin

Keyword(s):

Hong Kong ◽

Influenza A Virus ◽

Human Population ◽

Influenza A ◽

H1n1 Virus ◽

H1n1 Influenza ◽

H3n2 Virus ◽

Influenza A H1n1 ◽

Antibody Titres

SUMMARYSera from people born between 1883 and 1930 and collected in 1977 were tested for the presence of HI antibodies to A/FM/1/47 (H1N1) virus and three recently (1977 and 1978) isolated influenza A-H1N1 viruses. The highest frequency of high-titred antibody to the four H1N1 viruses was detected in sera from people born in 1903–4, i.e. 42,54,38, and 22% had antibody against A/FM/1/47, A/Hong Kong/117/77, A/Brazil/11/78, and A/Fukushima/103/78 respectively. The birthdate groups 1896–1907 showed a higher percentage of HI antibody titres ≥18, ≥50, ≥100 or ≥1600 against the four H1N1 viruses than the birthdate groups 1907–30. This indicates the existence of an era, 1908–18, in which, apart from the H3N2 virus (1900–18), the H1N1 virus was epidemic among the human population.

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Oseltamivir-Resistant Variants of the 2009 Pandemic H1N1 Influenza A Virus Are Not Attenuated in the Guinea Pig and Ferret Transmission Models

Journal of Virology ◽

10.1128/jvi.01424-10 ◽

2010 ◽

Vol 84 (21) ◽

pp. 11219-11226 ◽

Cited By ~ 80

Author(s):

Christopher W. Seibert ◽

Michael Kaminski ◽

Jennifer Philipp ◽

Dennis Rubbenstroth ◽

Randy A. Albrecht ◽

...

Keyword(s):

Guinea Pig ◽

Influenza A Virus ◽

Influenza A ◽

H1n1 Virus ◽

H1n1 Influenza ◽

Viral Fitness ◽

Pandemic H1n1 ◽

Number Of Patients ◽

2009 H1n1 ◽

Transmission Models

ABSTRACT Oseltamivir is routinely used worldwide for the treatment of severe influenza A virus infection, and should drug-resistant pandemic 2009 H1N1 viruses become widespread, this potent defense strategy might fail. Oseltamivir-resistant variants of the pandemic 2009 H1N1 influenza A virus have been detected in a substantial number of patients, but to date, the mutant viruses have not moved into circulation in the general population. It is not known whether the resistance mutations in viral neuraminidase (NA) reduce viral fitness. We addressed this question by studying transmission of oseltamivir-resistant mutants derived from two different isolates of the pandemic H1N1 virus in both the guinea pig and ferret transmission models. In vitro, the virus readily acquired a single histidine-to-tyrosine mutation at position 275 (H275Y) in viral neuraminidase when serially passaged in cell culture with increasing concentrations of oseltamivir. This mutation conferred a high degree of resistance to oseltamivir but not zanamivir. Unexpectedly, in guinea pigs and ferrets, the fitness of viruses with the H275Y point mutation was not detectably impaired, and both wild-type and mutant viruses were transmitted equally well from animals that were initially inoculated with 1:1 virus mixtures to naïve contacts. In contrast, a reassortant virus containing an oseltamivir-resistant seasonal NA in the pandemic H1N1 background showed decreased transmission efficiency and fitness in the guinea pig model. Our data suggest that the currently circulating pandemic 2009 H1N1 virus has a high potential to acquire drug resistance without losing fitness.

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Experiences after Twenty Months with Pandemic Influenza A (H1N1) 2009 Infection in the Naïve Norwegian Pig Population

Influenza Research and Treatment ◽

10.1155/2011/206975 ◽

2011 ◽

Vol 2011 ◽

pp. 1-7 ◽

Cited By ~ 4

Author(s):

B. Gjerset ◽

C. Er ◽

S. Løtvedt ◽

A. Jørgensen ◽

O. Hungnes ◽

...

Keyword(s):

Influenza A Virus ◽

Influenza A ◽

Clinical Signs ◽

Swine Influenza ◽

Active Phase ◽

Pandemic H1n1 ◽

Susceptible Population ◽

Influenza A H1n1 ◽

Pandemic H1n1 2009 ◽

Ongoing Infection

Pandemic (H1N1) 2009 influenza A virus was detected in Norwegian pigs in October 2009. Until then, Norway was regarded free of swine influenza. Intensified screening revealed 91 positive herds within three months. The virus was rapidly transmitted to the susceptible population, including closed breeding herds with high biosecurity. Humans were important for the introduction as well as spread of the virus to pigs. Mild or no clinical signs were observed in infected pigs. Surveillance of SIV in 2010 revealed that 41% of all the Norwegian pig herds had antibodies to pandemic (H1N1) 2009 virus. Furthermore, this surveillance indicated that pigs born in positive herds after the active phase did not seroconvert, suggesting no ongoing infection in the herds. However, results from surveillance in 2011 show a continuing spread of the infection in many herds, either caused by new introduction or by virus circulation since 2009.

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Influenza A (H1N1) Virus Infection in Hematologic patients In The South And West Of Spain

Blood ◽

10.1182/blood.v116.21.1740.1740 ◽

2010 ◽

Vol 116 (21) ◽

pp. 1740-1740

Author(s):

Fátima de la Cruz-Vicente ◽

Vicente Rubio ◽

Encarnación Gil-Esparraga ◽

Juan Bergua ◽

Élvira González ◽

...

Keyword(s):

Mechanical Ventilation ◽

Virus Infection ◽

Influenza A Virus ◽

Influenza A ◽

H1n1 Virus ◽

Clinical Course ◽

Influenza A H1n1 ◽

2009 H1n1 ◽

Influenza H1n1 ◽

H1n1 Virus Infection

Abstract Abstract 1740 Background: Patients with hematologic malignancies are likely to be at an increased risk for influenza infection. A few small series have documented seasonal influenza outbreaks among such patients, demonstrating the susceptibility of immunocompromised populations. These limited reports suggest that cancer patients are at a high risk for acquisition of influenza in both the community and health care settings. In April 2009, Mexico reported Influenza A virus outbreak. The virus was recognized as a novel known as Influenza A/pandemic 2009/H1N1 or 2009 H1N1 Influenza A. At present, there is scarce information on the clinical course of influenza A virus infection in hematologic patients. Objectives: To analyze the clinical course and laboratory characteristics of a cohort of hematologic patients diagnosed with influenza virus H1N1. Patients and Methods: Prospective study in five centers in Andalucia and Extremadura (Spain), in hematologic patients who developed an influenza H1N1 virus infection in the winter of 2009. Clinical characteristics, laboratory, radiological findings and clinical course were collected and analyzed. Diagnosis of the infection was made by viral isolation determined by PCR in pharyngal or nasal samples or both. Patients were followed during at least one month after diagnosis of infection. Non-normal distribution data were expressed as median values (range). Chi-square test or Fisher exact test were used to compare differences between groups of categorical data. Differences were considered statistically significant for p-values <0.05. All statistical analyses were performed using SPSS 17.0 software (Chicago, IL). Results: A total of twenty-nine patients entered the study between September and December 2009. One patient had been vaccinated against influenza H1N1 virus. Fifty per cent were female, with a median age of 40 years (3-78). Hematolgic diseases were: acute leukemia (24.1%), multiple myeloma 13.8%, non-hodgkin lymphomas 17.2%, Hodgkin lymphoma 20.7%, chronic lymphocytic leukemia 10.3%, myelodysplastic syndrome 3.4%, hemoglobinopathies 6.9% and other hematologic diseases 3.4%. Twelve (41.4%) patients were hematopoietic stem cell recipients: allogeneic (58.3%), most of them from identical sibling (85.7%) and peripheral blood source (91.7%) and autologous (41.7%). Lymphopenia was observed in 72.4% cases and neutropenia in 27.6% cases. The median days between the initial symptoms and diagnosis was 2 days (0-7). Most patients were in an outpatient basis (82.2%) and only 8 patients (27.6%) were hospitalized for these reason. Thirteen patients (44.8%) presented radiologic findings: interstitial changes (54.5%) and alveolar condensation (45.5%). 28 patients received treatment with oseltamivir, most of them at 75 mg/12 h, during a median of 5 days (1-21) and 21 patients received simultaneously another antimicrobial therapy. Six patients (20.7%) needed mechanical ventilation. At the end of the follow up the global mortality was 20.7% (6 cases) being three death (10.3) caused by influenza A H1N1 virus infection. There was an increase risk of mortality in patients who had pneumonia at the beginning of the infection (9.5% vs 50%, p=0.033), suffered a respiratory co-infection (8% vs 60%, p=0.008), developed respiratory complications (0 vs 46.1%, p=0.005), progressed to pneumonia during the infection (4.7% vs 71.4%, p=0.001) or required mechanical ventilation (8% vs 66.7%, p=0.008). There were no differences in the evolution of HSCT recipients. Conclusions: Respiratory co-infection, pneumonia at the beginning or during the infection and mechanical ventilation showed a relationship with fatal clinical course of influenza A/H1N1 virus infection in haematologic patients. Disclosures: No relevant conflicts of interest to declare.

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A structure-free digital microfluidic platform for detection of influenza a virus by using magnetic beads and electromagnetic forces

Lab on a Chip ◽

10.1039/c9lc01126a ◽

2020 ◽

Vol 20 (4) ◽

pp. 789-797 ◽

Cited By ~ 6

Author(s):

Po-Hsien Lu ◽

Yu-Dong Ma ◽

Chien-Yu Fu ◽

Gwo-Bin Lee

Keyword(s):

Influenza A Virus ◽

Influenza A ◽

Magnetic Beads ◽

H1n1 Virus ◽

Virus Detection ◽

Electromagnetic Forces ◽

Microfluidic Platform ◽

Influenza A H1n1 ◽

New Type ◽

Digital Microfluidic

A new type of digital microfluidic platform for influenza A H1N1 virus detection by utilizing a one-aptamer/two-antibodies assay on magnetic beads was reported.

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Infrarenal Aorta Thrombosis Associated with H1N1 Influenza A Virus Infection

Case Reports in Infectious Diseases ◽

10.1155/2016/9567495 ◽

2016 ◽

Vol 2016 ◽

pp. 1-3 ◽

Cited By ~ 2

Author(s):

Can Hüzmeli ◽

Mustafa Saglam ◽

Ali Arıkan ◽

Barıs Doner ◽

Gulay Akıncı ◽

...

Keyword(s):

Virus Infection ◽

Influenza A Virus ◽

Influenza A ◽

H1n1 Virus ◽

H1n1 Influenza ◽

Influenza Viruses ◽

Infrarenal Aorta ◽

Influenza A H1n1 ◽

Polymerase Chain ◽

Influenza A Virus Infection

Influenza viruses are members of the Orthomyxoviridae family, of which influenza A, B, and C viruses constitute three separate genera. Arterial thrombosis associated with H1N1 influenza A virus infection has rarely been reported. A Turkish man aged 28 years was admitted to our emergency department with dyspnea, bilateral lower extremity insensitivity, and cold. He reported symptoms of fever, myalgia, and cough, which he had had for fifteen days before being admitted to our hospital. The patient was tested for pandemic influenza A (H1N1) virus using polymerase chain reaction (PCR) tests, which were positive. Abdominal computerized tomography with contrast revealed a large occlusive thrombus within the infrarenal aorta.

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