Influenza

2021 ◽  
Author(s):  
Leong Hoe Nam
Keyword(s):  
Influenza Virus ◽  
Pandemic Influenza ◽  
Influenza A ◽  
Respiratory Infections ◽  
Rna Virus ◽  
Treatment Options ◽  
Antigenic Drift ◽  
New Techniques ◽  
Influenza A H1n1 ◽  
Viral Respiratory Infections

The influenza virus is a segmented RNA virus with different mechanisms for mutations, and hence for minor (antigenic drift) and major (antigenic shift) changes. Influenza virus A was responsible for pandemics on average every 30 years in the past, with the most recent being the 2009 swine-origin influenza A H1N1 (SO-H1N1). The clinical picture is unspecific: seasonal or pandemic influenza cannot be differentiated from other viral respiratory infections on clinical grounds. PCR has become the standard for microbiological confirmation of the diagnosis. Treatment options remain limited with neuraminidase inhibitors (oseltamivir; zanamivir). Resistance may occur under treatment or under prophylaxis; however, it is still rare overall. Vaccination is still the preferred method for prevention. However, the long lead time for production (at least 6 months) poses a challenge. Innovative new techniques like cell culture or recombinant productions are urgently needed. Pandemic influenza vaccines for SO-H1N1 were shown to be effective and safe in children, pregnant women, adults, and also in elderly. Pre-pandemic vaccines (H5N1) are also available.

scholarly journals Contemporary Seasonal Influenza A (H1N1) Virus Infection Primes for a More Robust Response To Split Inactivated Pandemic Influenza A (H1N1) Virus Vaccination in Ferrets

2010 ◽  
Vol 17 (12) ◽  
pp. 1998-2006 ◽  
Author(s):  
Ali H. Ellebedy ◽  
Thomas P. Fabrizio ◽  
Ghazi Kayali ◽  
Thomas H. Oguin ◽  
Scott A. Brown ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Pandemic Influenza ◽  
Influenza A ◽  
Seasonal Influenza ◽  
H1n1 Virus ◽  
H1n1 Influenza ◽  
Influenza Viruses ◽  
Inactivated Vaccine ◽  
H1n1 Influenza Virus ◽  
Influenza A H1n1

ABSTRACT Human influenza pandemics occur when influenza viruses to which the population has little or no immunity emerge and acquire the ability to achieve human-to-human transmission. In April 2009, cases of a novel H1N1 influenza virus in children in the southwestern United States were reported. It was retrospectively shown that these cases represented the spread of this virus from an ongoing outbreak in Mexico. The emergence of the pandemic led to a number of national vaccination programs. Surprisingly, early human clinical trial data have shown that a single dose of nonadjuvanted pandemic influenza A (H1N1) 2009 monovalent inactivated vaccine (pMIV) has led to a seroprotective response in a majority of individuals, despite earlier studies showing a lack of cross-reactivity between seasonal and pandemic H1N1 viruses. Here we show that previous exposure to a contemporary seasonal H1N1 influenza virus and to a lesser degree a seasonal influenza virus trivalent inactivated vaccine is able to prime for a higher antibody response after a subsequent dose of pMIV in ferrets. The more protective response was partially dependent on the presence of CD8+ cells. Two doses of pMIV were also able to induce a detectable antibody response that provided protection from subsequent challenge. These data show that previous infection with seasonal H1N1 influenza viruses likely explains the requirement for only a single dose of pMIV in adults and that vaccination campaigns with the current pandemic influenza vaccines should reduce viral burden and disease severity in humans.

Viral respiratory infections during the 2009 influenza A(H1N1) outbreak in the West Midlands Region, UK

2011 ◽  
Vol 140 (9) ◽  
pp. 1551-1556 ◽  
Author(s):  
H. E. TANNER ◽  
M. D. CURRAN ◽  
E. H. BOXALL ◽  
H. OSMAN
Keyword(s):  
Influenza A ◽  
Respiratory Infections ◽  
Respiratory Viruses ◽  
Virus Infections ◽  
Influenza Outbreak ◽  
Influenza A H1n1 ◽  
Significant Difference ◽  
West Midlands ◽  
The Uk ◽  
Viral Respiratory Infections

SUMMARYIn spring 2009 a new strain of influenza A(H1N1) emerged and caused a worldwide pandemic. This study utilized a large collection of respiratory specimens from suspected cases of influenza A(H1N1) in the UK West Midlands during the pandemic in order to investigate which other respiratory viruses were circulating and whether they played any role in the increased hospitalization rates seen during that period. Study specimens were selected from community and hospitalized patients positive and negative for influenza A(H1N1) and tested by PCR for other respiratory viruses. A number of infections diagnosed as influenza during the summer influenza outbreak were found to be due to other virus infections (most commonly rhinovirus). No statistically significant difference was found between the rates of respiratory virus co-infection with H1N1 in patients from community or hospital locations suggesting underlying factors were likely to be more significant than viral co-infections in determining severity of influenza A(H1N1) disease.

scholarly journals Effect of the 2009 Influenza A/H1N1 Pandemic on Viral Respiratory Infections in the First Year of Life

2012 ◽  
Vol 31 (11) ◽  
pp. 1107-1112 ◽  
Author(s):  
Linda C. Ede ◽  
Michael J. Loeffelholz ◽  
Pedro Alvarez-Fernandez ◽  
Dan L. Pong ◽  
Janak A. Patel ◽  
...  
Keyword(s):  
Influenza A ◽  
Respiratory Infections ◽  
First Year ◽  
H1n1 Pandemic ◽  
Influenza A H1n1 ◽  
Viral Respiratory Infections ◽  
First Year Of Life ◽  
Viral Respiratory

scholarly journals Preparing intensive care for the next pandemic influenza

Critical Care ◽  
2019 ◽  
Vol 23 (1) ◽  
Author(s):  
Taylor Kain ◽  
Robert Fowler
Keyword(s):  
Resource Allocation ◽  
Influenza Virus ◽  
Intensive Care ◽  
Pandemic Influenza ◽  
Influenza A ◽  
Large Scale ◽  
Influenza Pandemic ◽  
Influenza Viruses ◽  
Antigenic Drift ◽  
Timely Initiation

Abstract Few viruses have shaped the course of human history more than influenza viruses. A century since the 1918–1919 Spanish influenza pandemic—the largest and deadliest influenza pandemic in recorded history—we have learned much about pandemic influenza and the origins of antigenic drift among influenza A viruses. Despite this knowledge, we remain largely underprepared for when the next major pandemic occurs. While emergency departments are likely to care for the first cases of pandemic influenza, intensive care units (ICUs) will certainly see the sickest and will likely have the most complex issues regarding resource allocation. Intensivists must therefore be prepared for the next pandemic influenza virus. Preparation requires multiple steps, including careful surveillance for new pandemics, a scalable response system to respond to surge capacity, vaccine production mechanisms, coordinated communication strategies, and stream-lined research plans for timely initiation during a pandemic. Conservative models of a large-scale influenza pandemic predict more than 170% utilization of ICU-level resources. When faced with pandemic influenza, ICUs must have a strategy for resource allocation as strain increases on the system. There are several current threats, including avian influenza A(H5N1) and A(H7N9) viruses. As humans continue to live in closer proximity to each other, travel more extensively, and interact with greater numbers of birds and livestock, the risk of emergence of the next pandemic influenza virus mounts. Now is the time to prepare and coordinate local, national, and global efforts.

scholarly journals High frequency of cross-reacting antibodies against 2009 pandemic influenza A(H1N1) virus among the elderly in Finland

2010 ◽  
Vol 15 (5) ◽  
Author(s):  
N Ikonen ◽  
M Strengell ◽  
L Kinnunen ◽  
P Österlund ◽  
J Pirhonen ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Pandemic Influenza ◽  
Influenza A ◽  
Seasonal Influenza ◽  
H1n1 Virus ◽  
The Elderly ◽  
Influenza Viruses ◽  
Spanish Influenza ◽  
Pandemic Virus ◽  
Influenza A H1n1

Since May 2009, the pandemic influenza A(H1N1) virus has been spreading throughout the world. Epidemiological data indicate that the elderly are underrepresented among the ill individuals. Approximately 1,000 serum specimens collected in Finland in 2004 and 2005 from individuals born between 1909 and 2005, were analysed by haemagglutination-inhibition test for the presence of antibodies against the 2009 pandemic influenza A(H1N1) and recently circulating seasonal influenza A viruses. Ninety-six per cent of individuals born between 1909 and 1919 had antibodies against the 2009 pandemic influenza virus, while in age groups born between 1920 and 1944, the prevalence varied from 77% to 14%. Most individuals born after 1944 lacked antibodies to the pandemic virus. In sequence comparisons the haemagglutinin (HA) gene of the 2009 pandemic influenza A(H1N1) virus was closely related to that of the Spanish influenza and 1976 swine influenza viruses. Based on the three-dimensional structure of the HA molecule, the antigenic epitopes of the pandemic virus HA are more closely related to those of the Spanish influenza HA than to those of recent seasonal influenza A(H1N1) viruses. Among the elderly, cross-reactive antibodies against the 2009 pandemic influenza virus, which likely originate from infections caused by the Spanish influenza virus and its immediate descendants, may provide protective immunity against the present pandemic virus.

Effect of the 2009 Influenza A/H1N1 Pandemic on Viral Respiratory Infections in the First Year of Life

2013 ◽  
Vol 32 (1) ◽  
pp. 95-96
Author(s):  
Catiane Tiecher Cusinato ◽  
Caroline Beck ◽  
Nêmora Tregnago Barcellos ◽  
Fernando Herz Wolff
Keyword(s):  
Influenza A ◽  
Respiratory Infections ◽  
First Year ◽  
H1n1 Pandemic ◽  
Influenza A H1n1 ◽  
Viral Respiratory Infections ◽  
First Year Of Life ◽  
Viral Respiratory

scholarly journals Combination Therapy with Oseltamivir and Favipiravir Delays Mortality but Does Not Prevent Oseltamivir Resistance in Immunodeficient Mice Infected with Pandemic A(H1N1) Influenza Virus

Viruses ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 610 ◽  
Author(s):  
Mariana Baz ◽  
Julie Carbonneau ◽  
Chantal Rhéaume ◽  
Marie-Hélène Cavanagh ◽  
Guy Boivin
Keyword(s):  
Influenza Virus ◽  
Combination Therapy ◽  
Pandemic Influenza ◽  
Influenza A ◽  
Lethal Dose ◽  
Survival Rates ◽  
Oseltamivir Resistance ◽  
Immunodeficient Mice ◽  
Influenza A H1n1 ◽  
Viral Titers

Immunosuppressed individuals can shed influenza virus for prolonged periods of time, leading to the frequent emergence of antiviral resistance. We evaluated the benefits of oseltamivir and favipiravir combination therapy compared to single antiviral agents and monitored the emergence of drug-resistant variants in a pharmacologically immunosuppressed mouse model infected with the A(H1N1) pandemic influenza virus. C57BL/6 mice were immunosuppressed with cyclophosphamide and infected with a lethal dose of pandemic influenza A(H1N1) virus. Forty-eight hours post-infection, mice were treated with oseltamivir (20 mg/kg), favipiravir (20 or 50 mg/kg) or both agents BID for 5 or 10 days. Body weight losses, survival rates, lung viral titers, cytokine levels and emergence of resistant viruses were evaluated. Treatment of immunosuppressed mice with high (50 mg/kg) but not low (20 mg/kg) doses of favipiravir in combination with oseltamivir (20 mg/kg) significantly delayed mortality and reduced lung viral titers compared to treatment with a single drug regimen with oseltamivir but did not prevent the emergence of oseltamivir-resistant H275Y neuraminidase variants. Combination therapy with oseltamivir and favipiravir should be considered for evaluation in clinical trials.

scholarly journals In Vitro and In Vivo Characterization of Novel Neuraminidase Substitutions in Influenza A(H1N1)pdm09 Virus Identified Using Laninamivir-Mediated In Vitro Selection

2019 ◽  
Vol 93 (6) ◽  
Author(s):  
Khristine Kaith S. Lloren ◽  
Jin Jung Kwon ◽  
Won-Suk Choi ◽  
Ju Hwan Jeong ◽  
Su Jeong Ahn ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Deep Sequencing ◽  
Pandemic Influenza ◽  
Influenza A ◽  
Viral Fitness ◽  
Pdm09 Virus ◽  
Influenza A H1n1 ◽  
Na Gene

ABSTRACT Neuraminidase (NA) inhibitors (NAIs) are widely used antiviral drugs for the treatment of humans with influenza virus infections. There have been widespread reports of NAI resistance among seasonal A(H1N1) viruses, and most have been identified in oseltamivir-exposed patients or those treated with other NAIs. Thus, monitoring and identifying NA markers conferring resistance to NAIs—particularly newly introduced treatments—are critical to the management of viral infections. Therefore, we screened and identified substitutions conferring resistance to laninamivir by enriching random mutations in the NA gene of the 2009 pandemic influenza [A(H1N1)pdm09] virus followed by deep sequencing of the laninamivir-selected variants. After the generation of single mutants possessing each identified mutation, two A(H1N1)pdm09 recombinants possessing novel NA gene substitutions (i.e., D199E and P458T) were shown to exhibit resistance to more than one NAI. Of note, mutants possessing P458T—which is located outside of the catalytic or framework residue of the NA active site—exhibited highly reduced inhibition by all four approved NAIs. Using MDCK cells, we observed that the in vitro viral replication of the two recombinants was lower than that of the wild type (WT). Additionally, in infected mice, decreased mortality and/or mean lung viral titers were observed in mutants compared with the WT. Reverse mutations to the WT were observed in lung homogenate samples from D199E-infected mice after 3 serial passages. Overall, the novel NA substitutions identified could possibly emerge in influenza A(H1N1)pdm09 viruses during laninamivir therapy and the viruses could have altered NAI susceptibility, but the compromised in vitro/in vivo viral fitness may limit viral spreading. IMPORTANCE With the widespread emergence of NAI-resistant influenza virus strains, continuous monitoring of mutations that confer antiviral resistance is needed. Laninamivir is the most recently approved NAI in several countries; few data exist related to the in vitro selection of viral mutations conferring resistance to laninamivir. Thus, we screened and identified substitutions conferring resistance to laninamivir by random mutagenesis of the NA gene of the 2009 pandemic influenza [A(H1N1)pdm09] virus strain followed by deep sequencing of the laninamivir-selected variants. We found several novel substitutions in NA (D199E and P458T) in an A(H1N1)pdm09 background which conferred resistance to NAIs and which had an impact on viral fitness. Our study highlights the importance of continued surveillance for potential antiviral-resistant variants and the development of alternative therapeutics.

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