scholarly journals Prevalent Eurasian avian-like H1N1 swine influenza virus with 2009 pandemic viral genes facilitating human infection

2020 ◽  
Vol 117 (29) ◽  
pp. 17204-17210 ◽  
Author(s):  
Honglei Sun ◽  
Yihong Xiao ◽  
Jiyu Liu ◽  
Dayan Wang ◽  
Fangtao Li ◽  
...  
Keyword(s):  
Influenza Virus ◽  
H1n1 Virus ◽  
Swine Influenza Virus ◽  
Swine Influenza ◽  
Airway Epithelial Cells ◽  
Cross Reactivity ◽  
Human Infection ◽  
Influenza Viruses ◽  
Progeny Virus ◽  
Genotype 4

Pigs are considered as important hosts or “mixing vessels” for the generation of pandemic influenza viruses. Systematic surveillance of influenza viruses in pigs is essential for early warning and preparedness for the next potential pandemic. Here, we report on an influenza virus surveillance of pigs from 2011 to 2018 in China, and identify a recently emerged genotype 4 (G4) reassortant Eurasian avian-like (EA) H1N1 virus, which bears 2009 pandemic (pdm/09) and triple-reassortant (TR)-derived internal genes and has been predominant in swine populations since 2016. Similar to pdm/09 virus, G4 viruses bind to human-type receptors, produce much higher progeny virus in human airway epithelial cells, and show efficient infectivity and aerosol transmission in ferrets. Moreover, low antigenic cross-reactivity of human influenza vaccine strains with G4 reassortant EA H1N1 virus indicates that preexisting population immunity does not provide protection against G4 viruses. Further serological surveillance among occupational exposure population showed that 10.4% (35/338) of swine workers were positive for G4 EA H1N1 virus, especially for participants 18 y to 35 y old, who had 20.5% (9/44) seropositive rates, indicating that the predominant G4 EA H1N1 virus has acquired increased human infectivity. Such infectivity greatly enhances the opportunity for virus adaptation in humans and raises concerns for the possible generation of pandemic viruses.

scholarly journals Influenza at the animal–human interface: a review of the literature for virological evidence of human infection with swine or avian influenza viruses other than A(H5N1)

2014 ◽  
Vol 19 (18) ◽  
Author(s):  
G S Freidl ◽  
A Meijer ◽  
E de Bruin ◽  
M de Nardi ◽  
O Munoz ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Avian Influenza ◽  
Influenza A ◽  
Swine Influenza Virus ◽  
Swine Influenza ◽  
Human Infection ◽  
Influenza Viruses ◽  
Diagnostic Methods ◽  
World Health ◽  
Review Of The Literature

Factors that trigger human infection with animal influenza virus progressing into a pandemic are poorly understood. Within a project developing an evidence-based risk assessment framework for influenza viruses in animals, we conducted a review of the literature for evidence of human infection with animal influenza viruses by diagnostic methods used. The review covering Medline, Embase, SciSearch and CabAbstracts yielded 6,955 articles, of which we retained 89; for influenza A(H5N1) and A(H7N9), the official case counts of the World Health Organization were used. An additional 30 studies were included by scanning the reference lists. Here, we present the findings for confirmed infections with virological evidence. We found reports of 1,419 naturally infected human cases, of which 648 were associated with avian influenza virus (AIV) A(H5N1), 375 with other AIV subtypes, and 396 with swine influenza virus (SIV). Human cases naturally infected with AIV spanned haemagglutinin subtypes H5, H6, H7, H9 and H10. SIV cases were associated with endemic SIV of H1 and H3 subtype descending from North American and Eurasian SIV lineages and various reassortants thereof. Direct exposure to birds or swine was the most likely source of infection for the cases with available information on exposure.

scholarly journals Swine-Origin H1 Influenza Viruses Isolated from Humans Exhibit Sustained Infectivity in an Aerosol State

2019 ◽  
Vol 85 (10) ◽  
Author(s):  
Joanna A. Pulit-Penaloza ◽  
Jessica A. Belser ◽  
Terrence M. Tumpey ◽  
Taronna R. Maines
Keyword(s):  
Influenza Virus ◽  
Swine Influenza Virus ◽  
Virus Transmission ◽  
Swine Influenza ◽  
Influenza Viruses ◽  
Aerosol State ◽  
The Stability ◽  
Higher Doses ◽  
Enhanced Stability

ABSTRACT The relative importance of influenza virus transmission via aerosols is not fully understood, but experimental data suggest that aerosol transmission may represent a critical mode of influenza virus spread among humans. Decades ago, prototypical laboratory strains of influenza were shown to persist in aerosols; however, there is a paucity of data available covering currently circulating influenza viruses, which differ significantly from their predecessors. In this study, we evaluated the longevity of influenza viruses in aerosols generated in the laboratory. We selected a panel of H1 viruses that exhibit diverse transmission profiles in the ferret model, including four human isolates of swine origin (referred to as variant) and a seasonal strain. By measuring the ratio of viral RNA to infectious virus maintained in aerosols over time, we show that influenza viruses known to transmit efficiently through the air display enhanced stability in an aerosol state for prolonged periods compared to those viruses that do not transmit as efficiently. We then assessed whether H1 influenza virus was still capable of infecting and causing disease in ferrets after being aged in suspended aerosols. Ferrets exposed to very low levels of influenza virus (≤17 PFU) in aerosols aged for 15 or 30 min became infected, with five of six ferrets shedding virus in nasal washes at titers on par with ferrets who inhaled higher doses of unaged influenza virus. We describe here an underreported characteristic of influenza viruses, stability in aerosols, and make a direct connection to the role this characteristic plays in influenza transmission. IMPORTANCE Each time a swine influenza virus transmits to a human, it provides an opportunity for the virus to acquire adaptations needed for sustained human-to-human transmission. Here, we use aerobiology techniques to test the stability of swine-origin H1 subtype viruses in aerosols and evaluate their infectivity in ferrets. Our results show that highly transmissible influenza viruses display enhanced stability in an aerosol state compared to viruses that do not transmit as efficiently. Similar to human-adapted strains, swine-origin influenza viruses are infectious in ferrets at low doses even after prolonged suspension in the air. These data underscore the risk of airborne swine-origin influenza viruses and support the need for continued surveillance and refinement of innovative laboratory methods to investigate mammalian exposure to inhaled pathogens. Determination of the molecular markers that affect the longevity of airborne influenza viruses will improve our ability to quickly identify emerging strains that present the greatest threat to public health.

scholarly journals Mutations in the NS1 Protein of Swine Influenza Virus Impair Anti-Interferon Activity and Confer Attenuation in Pigs

2005 ◽  
Vol 79 (12) ◽  
pp. 7535-7543 ◽  
Author(s):  
Alicia Solórzano ◽  
Richard J. Webby ◽  
Kelly M. Lager ◽  
Bruce H. Janke ◽  
Adolfo García-Sastre ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Nonstructural Protein ◽  
Swine Influenza Virus ◽  
Swine Influenza ◽  
Influenza Viruses ◽  
Model Systems ◽  
Ns1 Protein ◽  
Wild Type ◽  
Virulence Attenuation

ABSTRACT It has been shown previously that the nonstructural protein NS1 of influenza virus is an alpha/beta interferon (IFN-α/β) antagonist, both in vitro and in experimental animal model systems. However, evidence of this function in a natural host has not yet been obtained. Here we investigated the role of the NS1 protein in the virulence of a swine influenza virus (SIV) isolate in pigs by using reverse genetics. The virulent wild-type A/Swine/Texas/4199-2/98 (TX/98) virus and various mutants encoding carboxy-truncated NS1 proteins were rescued. Growth properties of TX/98 viruses with mutated NS1, induction of IFN in tissue culture, and virulence-attenuation in pigs were analyzed and compared to those of the recombinant wild-type TX/98 virus. Our results indicate that deletions in the NS1 protein decrease the ability of the TX/98 virus to prevent IFN-α/β synthesis in pig cells. Moreover, all NS1 mutant viruses were attenuated in pigs, and this correlated with the amount of IFN-α/β induced in vitro. These data suggest that the NS1 protein of SIV is a virulence factor. Due to their attenuation, NS1-mutated swine influenza viruses might have a great potential as live attenuated vaccine candidates against SIV infections of pigs.

scholarly journals Swine Influenza Virus PA and Neuraminidase Gene Reassortment into Human H1N1 Influenza Virus Is Associated with an Altered Pathogenic Phenotype Linked to Increased MIP-2 Expression

2015 ◽  
Vol 89 (10) ◽  
pp. 5651-5667 ◽  
Author(s):  
Daniel Dlugolenski ◽  
Les Jones ◽  
Elizabeth Howerth ◽  
David Wentworth ◽  
S. Mark Tompkins ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Sialic Acid ◽  
Influenza A ◽  
H1n1 Virus ◽  
Swine Influenza ◽  
Influenza Viruses ◽  
Pandemic H1n1 ◽  
Human Influenza ◽  
Swine Virus ◽  
Virus Reassortment

ABSTRACTSwine are susceptible to infection by both avian and human influenza viruses, and this feature is thought to contribute to novel reassortant influenza viruses. In this study, the influenza virus reassortment rate in swine and human cells was determined. Coinfection of swine cells with 2009 pandemic H1N1 virus (huH1N1) and an endemic swine H1N2 (A/swine/Illinois/02860/09) virus (swH1N2) resulted in a 23% reassortment rate that was independent of α2,3- or α2,6-sialic acid distribution on the cells. The reassortants had altered pathogenic phenotypes linked to introduction of the swine virus PA and neuraminidase (NA) into huH1N1. In mice, the huH1N1 PA and NA mediated increased MIP-2 expression early postinfection, resulting in substantial pulmonary neutrophilia with enhanced lung pathology and disease. The findings support the notion that swine are a mixing vessel for influenza virus reassortants independent of sialic acid distribution. These results show the potential for continued reassortment of the 2009 pandemic H1N1 virus with endemic swine viruses and for reassortants to have increased pathogenicity linked to the swine virus NA and PA genes which are associated with increased pulmonary neutrophil trafficking that is related to MIP-2 expression.IMPORTANCEInfluenza A viruses can change rapidly via reassortment to create a novel virus, and reassortment can result in possible pandemics. Reassortments among subtypes from avian and human viruses led to the 1957 (H2N2 subtype) and 1968 (H3N2 subtype) human influenza pandemics. Recent analyses of circulating isolates have shown that multiple genes can be recombined from human, avian, and swine influenza viruses, leading to triple reassortants. Understanding the factors that can affect influenza A virus reassortment is needed for the establishment of disease intervention strategies that may reduce or preclude pandemics. The findings from this study show that swine cells provide a mixing vessel for influenza virus reassortment independent of differential sialic acid distribution. The findings also establish that circulating neuraminidase (NA) and PA genes could alter the pathogenic phenotype of the pandemic H1N1 virus, resulting in enhanced disease. The identification of such factors provides a framework for pandemic modeling and surveillance.

scholarly journals Effect of health seeking interval on outcome in swine flu cases attended a tertiary care hospital in southern Rajasthan region of India

2019 ◽  
Vol 6 (7) ◽  
pp. 2910
Author(s):  
Shalabh Sharma ◽  
Yogesh Kumar Singhal
Keyword(s):  
Influenza Virus ◽  
Clinical Care ◽  
Swine Influenza Virus ◽  
Swine Influenza ◽  
Influenza Viruses ◽  
Swine Flu ◽  
Care Hospital ◽  
Health Seeking ◽  
Early Presentation ◽  
Number Of Patients

Background: Swine flu influenza is an infection by H1N1 type of swine influenza virus. Swine influenza virus or swine-origin influenza virus (SIV or S-OIV) is a strain of the family of influenza viruses that’s endemic in swine (pigs). Early diagnosis and treatment is key approach to control the morbidity and mortality associated with swine flu which can be achieved by improving health seeking behaviour of community. Understanding of behaviour of community is essential for planning strategies for prevention and control. Aim of this study is to establish a relation between healthcare interval and outcome of swine flu.Methods: A complete data of all the patients visiting swine flu OPDs, swine flu wards and ICU were maintained for year 2015. Each patient visiting either the swine flu OPD or the swine flu ward, who was suspected clinically to be H1N1 positive were tested for real time PCR. Data was collected in a standardized pre-structured questionnaire.Results: Out of 1247 samples tested for rt-PCR, number of patients found to be swine positive was 491 (39.37%). Total 267 patients were admitted in swine flu ward and ICU, out of them 62 was expired. Clinical care intervals of more than 5 days from onset of symptoms to swab collection, diagnosis and admission were more in female and rural population. Mean duration between onset of symptom to hospitalization, swab collection and diagnosis was significantly higher in deceased patients than survived.Conclusions: Early presentation to healthcare facility is associated with better prognosis and outcome. After patient report to the health care setup, early sample collection and diagnosis help to reduce mortality.

scholarly journals Resurrected ancestral influenza A viruses recapitulate the avian-to-mammalian adaptation of European avian-like swine influenza virus

2021 ◽  
Author(s):  
Wen Su ◽  
Rhodri Harfoot ◽  
Yvonne Su ◽  
Jennifer DeBeauchamp ◽  
Udayan Joseph ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Avian Influenza ◽  
Influenza A ◽  
Swine Influenza Virus ◽  
Swine Influenza ◽  
Polymerase Activity ◽  
Influenza Viruses ◽  
Mammalian Host ◽  
Influenza A Viruses ◽  
Sequence Reconstruction

Abstract The emergence of a pandemic influenza virus may be better anticipated if we better understand the evolutionary steps taken by avian influenza viruses as they adapt to mammals. We used ancestral sequence reconstruction to resurrect viruses representing initial adaptive stages of the European avian-like H1N1 virus as it transitioned from avian to swine hosts. We demonstrate that efficient transmissibility in pigs was gained through stepwise adaptation after 1983. These time-dependent adaptations resulted in changes in hemagglutinin receptor binding specificity and increased viral polymerase activity. An NP-R351K mutation under strong positive selection increased the transmissibility of a reconstructed virus. The stepwise-adaptation of a wholly avian influenza virus to a mammalian host suggests a window where targeted intervention may have highest impact. Successful intervention will, however, require strategic coordination of surveillance and risk assessment activities to identify these adapting viruses and guide pandemic preparedness resources.

Phylogeny of Spanish swine influenza viruses isolated from respiratory disease outbreaks and evolution of swine influenza virus within an endemically infected farm

2014 ◽  
Vol 170 (3-4) ◽  
pp. 266-277 ◽  
Author(s):  
Gerard E. Martín-Valls ◽  
Meritxell Simon-Grifé ◽  
Sander van Boheemen ◽  
Miranda de Graaf ◽  
Theo M. Bestebroer ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Respiratory Disease ◽  
Swine Influenza Virus ◽  
Swine Influenza ◽  
Disease Outbreaks ◽  
Influenza Viruses ◽  
Infected Farm

scholarly journals Migration of the Swine Influenza Virus δ-Cluster Hemagglutinin N-Linked Glycosylation Site from N142 to N144 Results in Loss of Antibody Cross-Reactivity

2012 ◽  
Vol 19 (9) ◽  
pp. 1457-1464 ◽  
Author(s):  
Ben M. Hause ◽  
Douglas L. Stine ◽  
Zizhang Sheng ◽  
Zhao Wang ◽  
Suvobrata Chakravarty ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Influenza A ◽  
Consensus Sequence ◽  
Swine Influenza Virus ◽  
Swine Influenza ◽  
Cross Reactivity ◽  
Glycosylation Site ◽  
Sequencing Analysis ◽  
Serum Neutralization ◽  
Glycosylation Sites

ABSTRACTRoutine antigenic characterization of swine influenza virus isolates in a high-throughput serum neutralization (HTSN) assay found that approximately 20% of isolates were not neutralized by a panel of reference antisera. Genetic analysis revealed that nearly all of the neutralization-resistant isolates possessed a seasonal human-lineage hemagglutinin (HA; δ cluster). Subsequent sequencing analysis of full-length HA identified a conserved N144 residue present only in neutralization-resistant strains. N144 lies in a predicted N-linked glycosylation consensus sequence, i.e., N-X-S/T (where X is any amino acid except for proline). Interestingly, neutralization-sensitive viruses all had predicted N-linked glycosylation sites at N137 or N142, with threonine (T) occupying position 144 of HA. Consistent with the HTSN assay, hemagglutination inhibition (HI) and serum neutralization (SN) assays demonstrated that migration of the potential N-linked glycosylation site from N137 or N142 to N144 resulted in a >8-fold decrease in titers. These results were further confirmed in a reverse genetics system where syngeneic viruses varying only by predicted N-glycosylation sites at either N142 or N144 exhibited distinct antigenic characteristics like those observed in field isolates. Molecular modeling of the hemagglutinin protein containing N142 or N144 in complex with a neutralizing antibody suggested that N144-induced potential glycosylation may sterically hinder access of antibodies to the hemagglutinin head domain, allowing viruses to escape neutralization. Since N-linked glycosylation at these sites has been implicated in genetic and antigenic evolution of human influenza A viruses, we conclude that the relocation of the hemagglutinin N-linked glycosylation site from N142 to N144 renders swine influenza virus δ-cluster viruses resistant to antibody-mediated neutralization.

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