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The influenza A virus is known to cause influenza in birds and some mammals, like humans. Several subtypes of the influenza A virus have been isolated from wild birds. Occasionally, viruses can be transmitted from wild birds to domestic animals, like chickens or pigs. This may give rise to human influenza.<ref name="Arti2">Transmission of Avian Influenza A Viruses Between Animals and People, CDC, 2015, https://www.cdc.gov/flu/avianflu/virus-transmission.htm</ref>
Influenza A viruses are negative-sense, single-stranded RNA viruses. Subtypes of influenza A are characterized by proteins on the outermost membrane of the virus, called hemagglutinin (H or HA) and neuraminidase (N or NA). H and N are the antigens of the virus, and play an important role in the interaction between the host’s immunological response and the virus. Recently, researchers have reported the discovery of an antibody which that is generally effective against all subtypes of the influenza A virus.<ref name="Arti3">Super antibody' fights off flu, BBC, 2011, James Gallagher, https://www.bbc.com/news/health-14324901</ref>
The subtype which will be used in SensUs 2021 is H1N1. Historically, H1N1 has been responsible for most deaths due to influenza. It is a popular influenza strain for research purposes.<ref name="Arti4">Prevalent Eurasian avian-like H1N1 swine influenza virus with 2009 pandemic viral genes facilitating human infection, Research Gate, 2020, Sun, Honglei & Xiao, Yihong & Liu, Jiyu & Wang, Dayan & Li, Fangtao & Wang, Chenxi & Li, Chong & Zhu, Junda & Song, Jingwei & Sun, Haoran & Zhimin, Jiang & Liu, Litao & Zhang, Xin & Wei, Kai & Dongjun, Hou & Pu, Juan & Sun, Yipeng & Tong, Qi & Bi, Yuhai & Liu, Jinhua https://www.researchgate.net/publication/342555087_Prevalent_Eurasian_avian-like_H1N1_swine_influenza_virus_with_2009_pandemic_viral_genes_facilitating_human_infection</ref><ref name="Arti5">Comparison of Hospitalized Patients With ARDS Caused by COVID-19 and H1N1, CHEST, Xiao Tang, Rong-Hui Du, Rui Wang, Tan-Ze Cao, Lu-Lu Guan, Cheng-Qing Yang, Qi Zhu, Ming Hu, Xu-Yan Li, Ying Li, Li-Rong Liang, Zhao-Hui Tong, Bing Sun, Peng Peng, Huan-Zhong Shi, 2020, https://www.sciencedirect.com/science/article/pii/S0012369220305584</ref><ref name="Arti6">Landscape of coordinated immune responses to H1N1 challenge in humans, Journal of Clinical Investigation, 2020, Zainab Rahil, Rebecca Leylek, Christian M. Schürch, Han Chen, Zach Bjornson-Hooper, Shannon R. Christensen, Pier Federico Gherardini, Salil S. Bhate, Matthew H. Spitzer, Gabriela K. Fragiadakis, Nilanjan Mukherjee, Nelson Kim, Sizun Jiang, Jennifer Yo, Brice Gaudilliere, Melton Affrime, Bonnie Bock, Scott E. Hensley, Juliana Idoyaga, Nima Aghaeepour, Kenneth Kim, Garry P. Nolan, David R. McIlwain https://www.sciencedirect.com/science/article/pii/S0012369220305584</ref> Due to its popularity among researchers, antigens and antibodies are commercially available, making H1N1 suitable as a target for the SensUs competitionCompetition.
Influenza A vaccines for humans have been developed. New versions of the vaccines are developed twice per year for use all over the world, which is necessary due to rapid mutations of the influenza virus. Every year during flu season, a large part of the population is vaccinated in order to protect individuals against the virus. However, due to unforeseen mutations of the virus, it might be possible that in a certain year a vaccine will prove ineffective. In that case large portions of the population would be at risk and a pandemic could occur. The probability of a major influenza A pandemic is estimated to be around 0.5-1% each year.<ref name="Arti7">Pandemic risk: how large are the expected losses?, WHO, 2017, Victoria Y Fan, Dean T Jamisonb & Lawrence H Summers, https://www.who.int/bulletin/volumes/96/2/17-199588.pdf</ref>
==History of influenza (A)==
A lack of data up until 1500 AC complicates the research on influenza before that period.<ref name="Arti8">Internet‐Based Intelligence in Public Health Emergencies, NATO Science for Peace and Security Series - E: Human and Societal Dynamics, 2013 Mordini E., Green M., https://www.iospress.nl/book/internet%E2%80%90based-intelligence-in-public-health-emergencies/</ref> Possibly the first influenza pandemic occurred around 6000 BC in China. The symptoms of human influenza seem to have been clearly described by Hippocrates, roughly 2,400 years ago<ref name="Arti9">2,500-year Evolution of the Term Epidemic, Emerging infectious diseases, 2006, Martin PM, Martin-Granel E, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3373038/</ref> Although the virus seems to have caused epidemics throughout human history, historical data on influenza is difficult to interpret, due to the fact that symptoms of influenza are similar to those found in other respiratory diseases, like RSV (respiratory syncytial virus(RSV).
The most infamous and lethal outbreak was the 1918 flu pandemic, which lasted into until 1920. The number of deaths is unknown, but estimates range from 17 to 100 million people.<ref name="Arti10">Reassessing the Global Mortality Burden of the 1918 Influenza Pandemic, American journal of epidemiology, 2018, Spreeuwenberg P, Kroneman M, Paget J, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7314216/</ref>. This pandemic has been described as "the greatest medical holocaust in history"<ref name="Arti11"> Reviewing the History of Pandemic Influenza: Understanding Patterns of Emergence and Transmission
, Pathogens, 2016, Saunders-Hastings PR, Krewski D, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5198166/</ref> and may have killed as many people as the plague (Black Death). This huge death toll was caused by an extremely high infection rate of up to 50% and the severity of the symptoms, suspected to be caused by cytokine storms in which the innate immune system causes an uncontrolled and excessive release of pro-inflammatory signaling molecules called cytokines.
One of the most recent outbreaks of influenza was the 2009 Swine Flu. Similar to the Spanish Flu, it was also of the subtype H1N1. The death toll of the 2009 pandemic is estimated to be around 150,000 to 575,000.<ref name="Arti12">2009 H1N1 Pandemic (H1N1pdm09 virus), centers for disease control and prevention, 2010, https://www.cdc.gov/flu/pandemic-resources/2009-h1n1-pandemic.html</ref>
For disease control, it is crucial to know the infection rate in a specific region. The results may influence critical decisions such as whether to perform other diagnostic testing or to implement infection prevention and control measures for influenza. Furthermore, manpower can be in short supply during a pandemic and the speed at which someone can be tested and receive the result is of vital importance.
Biosensors that will be developed in SensUs 2021 are envisioned to be used outside the hospital in a point-of-care (POC) setting. Inside the hospital there is not a big advantage, as there are already very specific and accurate tests available for that setting.<ref name="Arti28">Diagnosing Flu, CDC, 2020, https://www.cdc.gov/flu/symptoms/testing.htm</ref><ref name="Arti29">Information on Rapid Molecular Assays, RT-PCR, and other Molecular Assays for Diagnosis of Influenza Virus Infection, CDC, 2020, https://www.cdc.gov/flu/professionals/diagnosis/molecular-assays.htm</ref> Important applications are fast testing at the GP general practioner and at home. Therefore the test should be easy to use. The biosensors will be designed to enable a fast yes/no answer, based on measuring the concentration of viral particles in the sample. The biosensors will not distinguish between different virus subtypes, as the subtype causing the pandemic is assumed to be known.
==State of the Art==
There are various influenza tests available on the market. The most common tests are ‘rapid influenza diagnostic tests’, also called RIDTs. RIDTs provide results in a qualitative way within approximately 10-15 minutes and work by detecting the parts of the virus that stimulate an immune response.<ref name="Arti17">Rapid Influenza Diagnostic Tests, 2016, Centers for Disease Control and Prevention, https://www.cdc.gov/flu/professionals/diagnosis/clinician_guidance_ridt.htm</ref>
The table contains examples of available Rapid Influenza Diagnostic Tests rapid influenza diagnostic tests that provide results in 10-15 minutes. In the SensUs Competition, a saliva based test will be developed. Moreover, SensUs strives to develop stimulate developement of sensors that provide results within 5-10 minutes and that are as sensitive as possible. The SensUs Competition aims to innovate the field of influenza biosensing by using saliva as a matrix, by improving the speed of the test, and by targeting a high sensitivity.
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The use of safety equipment combined with good practices is fundamental to laboratory safety and in helping to reduce the risks involved in dealing with biosafety hazards. Therefore, it is important that you consult with your local biosafety officer and comply to the safety rules of your own organization.
According to Article 4.84 of the Working Conditions Decree in The Netherlands, inactivated virus particles can be classified as category 1 of the biological agents<ref name="Arti30">1Short manual for the ML-I, ML-II laboratory(gmo-labs) and/or laboratory for working with biological agents / human materials, University of Twente, 2018,https://www.utwente.nl/.uc/f4fcab199010209618400ac90d20284e61d13c337a78900/short-manual-gmo.pdf</ref>, as they are unlikely to cause disease in humans. Therefore, the biosafety guidelines as defined in the ML-1 (minimum containment level) have to be followed. It is stipulated in the guidelines that general laboratory protocols such as the usage of barrier protection (lab coats, gloves , and face protection) when handling the samples are to be followed. The protection barriers are not always necessary from a microbiological perspective. However, it is compulsory when handling disinfectants or solvents.
== References ==
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