Teddies Talks Biology - Issue 9

Special Issue:

Viruses & Vaccines

What is a zoonosis? How do vaccines work? Why are some people anti - vax?

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Dear Readers,

The past eighteen months have seen global disruption on a perhaps unprece- dented scale – and all due to a biological phenomenon!

I think it is safe to say that we at Teddies have weathered the storm remarka- bly well, thanks to all the collective efforts to keep school going, while limiting the spread of the virus within the school community. Inevitably, as people involved in education, we have seen this as a tremen- dous opportunity for learning. To both highlight and encourage this, the Ted- dies Talks Biology team decided to compile this Special Issue on Viruses & Vaccines . A range of pupils have produced articles on zoonoses (diseases spread from animals to humans), the immune response, vaccines and vaccine hesitancy. Of particular interest is a fascinating article by 4 th Form pupil Tom Phillips on a beneficial use of viruses, and an immunologically - inspired piece of creative writing by Upper 6 th pupil Mashia Jaafari. The issue closes off with an experimental evaluation of the environmental impact of waste produced during the pandemic, by 4 th Form Applied Science pupil Douggie Campbell. In reading this collection of articles, it should be noted that we learn more each day about coronaviruses, and so any information and opinions shared in these pages should not be taken as the final word on the matter. For sound scientific advice regarding Covid - 19 and vaccination readers should explore the resources of bodies such as the World Health Organisation and Public Health England .

With that proviso in place, we hope that you will enjoy our latest issue, and maybe learn a few things along the way. Happy reading!

Best regards, 

Mr Cazabon & the TTB Team

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Table of Contents:

1. Non - Bacterial Pathogens …....……………………………………. pg4 Ayesha Nurjahan & Emma Somers 2. What is a Zoonosis? …….………………………………………... pg6 Lucy Draper 3. How Can We Use Viruses to Kill Superbugs? ..…..……..…... pg7 Tom Phillips 4. Immune Response to Viral Infections ….……………………… pg8 Daniela Olinic 5. How do Vaccines work?. ……………….....…………………….. pg10 Emma Somers & Alexis Mpanga 6. Vaccine Hesitancy …….…………..………………..……..……... pg12 Anton Myachin 7. The Anti - vaccination Movement ….…………………………..… pg13 Ruby Freeland 8. A Pathogen ’ s Story ………………….……………….……..…….. pg14 Creative Writing by Mashia Jaafari 9. Covid Waste ………………………………………………………... pg16 SESC Applied Science Project by Douggie Campbell

Production Designer: Lily Tan

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Ayesha Nurjahan & Emma Somers—LVI

A virus can be defined as an obligate intracellular parasite. Each virion, or viral particle, con- sists of a single nucleic acid (RNA or DNA) encoding the viral genome, surrounded by a protein coat, and is capable of replication only within the living cells of bacteria, animals or plants. Influenza The virus family Orthomyxoviridae consists of the genera Influenza virus A, B and C. Major epidemics are caused by A and B, and it is usually these two varieties that cause the flu. They have a diameter of about 100 nanometres, making them a medium sized virus.

The influenza virus is roughly spherical. It is an enveloped virus, with an outer layer that is a lipid membrane which is taken from the host cell in which the virus multiplies.

Inserted into the lipid membrane are ‘ spikes ’, which are glycoproteins, because they consist of protein linked to sugars also known as hemagglutinin (HA) and neuraminidase (NA). These are the proteins that determine the subtype of influenza virus. The HA and NA are important in the immune response against the virus: antibodies against these spikes may protect against infection. The NA protein is the target of the antiviral drugs Relenza and Tamiflu.

The Covid - 19 Virus Particle or Virion

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(continued)

Stem Rust Fungus: A Plant Pathogen

The stem rust fungus attacks the parts of the plant that are above ground. Spores that land on green wheat plants form a pustule that invades the outer layers of the stalk. • The hypha secretes enzymes that digest plant tissue - the nutrients are absorbed into the fungus. • The hyphae branch to form a mycelium.

Infected plants produce fewer tillers and set fewer seed, and in cases of severe infection the plant may die. • Absorbs nutrients from the plant, reducing yield • Pustules break the epidermis making it harder to control transpiration - increased water loss • Mycelium grows into the vascular tissue - absorbing water and nutrients • Weakens stem

Spores are carried by wind to the cereal host where they germinate and the germ tubes pene- trate into the plant. The spore needs water to germinate

Plasmodium and Malaria

The Plasmodium parasite (a Protoctist) is transmitted by mosquito vector - the bite of a female Anopheles mosquito. The infection happens both ways - the female mosquito picks up malaria as well as giving it while anticoagulants prevent blood from clotting.

• Malaria parasite transmitted to per- son from infected female Anopheles mosquito • Parasites travel to the liver • Next stage of malarial parasites re- leased into blood where they invade RBCs • Parasites reproduce asexually and burst out of RBCs and destroy them - happens every 48 - 72 hours • Malarial parasite transmitted to a mosquito taking a meal where it can be transmitted to another person

Malaria causes flu - like symptoms caused by parasite bursting out of red blood cells • Symptoms include: fever, sweating, shaking, muscle pains, headaches. • Long term damage to liver and reduction in number of RBCs • This leads to weakness, anaemia and death • When in the human body, it is mostly hidden from the immune system by hiding in liver cells and RBCs.

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Lucy Draper—LVI

A Zoonosis is a disease that is transmitted from an animal into a human. The disease is usually either bacterial, viral, fungal or parasitic. These diseases are then transmitted via either vec- tors, bites or saliva into the human body. Examples of such diseases would be Rabies and Lymes Disease. Once inside the human body, pathogenesis occurs: this describes replication in the host. The success of the replication can be affected by host immunity, defence factors and cell/organ specific receptors. Replication of an animal virus within the first human host is a key turning point in the zoonotic process, as it leads to the mutation and evolution under selective restraints of the body If successful, and there is a high virus titre (large quantity of virus in a given volume) it means that spread to another human is possible, therefore initiating selection for variants with in- creased capacity to spread in the human population. How the Covid virus moved from animal to human populations is yet to be determined, however there has been speculation amongst the scientific community about how it was transferred across the populations.

Dr. David Robertson, head of viral genomics and bioinformatics at the University of Glas- gow, found that the closest ancestor of Covid - 19 had been living in bats already for up to 70 years prior, and that despite the lack of clarity of what happened between bats and humans it is very likely that the virus circulated for a while in a pangolin or another intermediary an- imal. His research on the virus ’ s genetic code proves beyond a shadow of a doubt that the

virus originated in nature, therefore highlighting that the transmission could be classified as a zoonosis, as long as it can be proven that the transmission occurred through either an interme- diary animal or a bat itself—which even experts disagree on.

However, it is clear that the virus has required no significant adaptations since the start of the pan- demic, this shows that the virus, which naturally evolves in bats, was almost immediately ready to be spread through human contact. Thus showing how it contained properties which were conducive to human infection already, regardless of how it originally transferred to humans. In research un- dertaken by J. Mackenzie and D. Smith the Angi- otensin - converting enzyme 2 (ACE2) was known to be the cell receptor (the molecule which let the virus into the body) for other coronaviruses. The receptor - binding domain for Covid - 19 was suffi- ciently similar to this, indicating that Covid - 19 could successfully use human ACE2 for receptor

entry into cells, showing that it would have always been highly transmissible whether it emerged into the human community by bats or otherwise. In all, the pandemic could be classi- fied as a zoonotic disease, however, no animal reservoir has yet been found, so the classifica- tion could be described as premature. Instead, it could be called an ‘ emerging infectious dis- ease ’ (EID) of probable animal origin until the real cause is found, if ever.

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Tom Phillips— 4 th Form

For about 100 years we have used antibiotics to treat all kinds of bacterial infections. They have served us well throughout the 20 th and 21 st centuries. However, like all living things, some bacteria have evolved to become resistant to antibiotics. Our next hope is to use the biggest killer of planet earth, viruses, to help us defeat super bugs.

These viruses are called bacteriophage, a very small structure of protein and DNA. They are not living as, like all virus- es, they need a host cell to reproduce. Bacteriophage inject their genetic materi- al into certain types of bacteria and con- trol the ribosomes in the bacteria to cre- ate more of itself. The virus produces en- dolysin, an enzyme which makes the bacteria explode and kills the cell. The process is then repeated. Bacteriophage have evolved to only target particular types of bacteria. Some have been dis- covered to aim for superbugs. But what are superbugs and how have we got to this point where drugs on the market now cannot kill these bacteria?

Bacteria are living things, like us they evolved to become better adapted to the surrounded to their environment. About 100 years ago Alexander Fleming discovered penicillin, a fungus that can kill bacteria. However recently we have been using antibiotics for less harmful bacteria in- fections, therefore the bacteria have become resistant to our drugs and have evolved into stronger bacteria that is supposedly indestructible. In fact, it is estimated that more people will die from Superbugs in 2050 than from cancer. Superbugs are a threat, but what can we do? This is when Bacteriophage come into play. Scientists are looking more than ever to use Bacteriophage to help us defeat superbugs, as some of these Bacteriophages use these superbugs as hosts. Unlike antibiotics the Bacterio- phage only specialise in one bacterium, meaning they would not be able to take over any good bacteria in our body that we need or our cells, but only superbugs. Antibiotics kill all types of bacteria. The use of these viruses is still in the experimental stage, but there was a man who had a chest infection of a type of superbug and the doctors used an experimental dose of a bacteriophage to kill the bacteria in his chest. He managed to survive, showing the potential these viruses must save lives.

The idea of using bacteriophage to kill superbugs is still in the experimental stage. However, there is much hope for these viruses. For hospitals to widely use them, regulatory bodies will have to approve them for general use. Scientists are working hard to make it safe. The future is looking hopeful for using bacteriophage to kill superbugs.

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Daniela Olinic—LVI

Viruses are microscopic parasites that cannot reproduce by themselves. They are known to cause contagion, such as the COVID - 19 pandemic, the Ebola outbreak from 2014 in West Afri- ca and the H1N1 pandemic. Once a virus infects a cell, it can control the cell machinery and cause it to produce more viruses. They have either DNA or RNA as genetic material. The virus particle, or virion, is made of a nucleic acid and an outer shell protein. Viruses can also be use- ful research tools for scientists as they help better our understanding of cellular processes such as protein synthesis. In case of viral infection, organisms generate a defense by triggering an immune response. There are 3 types of immunity: innate, adaptive, and passive. Innate immunity, also known as natural immunity, is the one anyone is born with, such as the skin as a barrier against germs or other foreign invaders. The adaptive, or active immune system develops through immuniza- tions or being exposed to disease during our lives. Passive immunity is a short - time source of immunity, like the antibodies a baby gets from the mother ’ s breast milk.

Innate immunity is a first line defense against viral infection or replication and is active even before the infection begins. The innate immune system responds very quickly, within minutes or hours after infection. Its main ability is to recognize viruses as foreign. This is done through

pattern recognition receptors that distin- guish the viral proteins and nucleic acids. These proteins are present either in the cell cytoplasm or on cell membranes, where they are recognized by the invaded cells. The presence of cytokines is also an early indication of viral infection within the host cell. Cytokines are secreted by the infected cells. They function by binding with other cells locally, but also by engaging neighbor- ing cells. These cells produce cellular pro- teins which have antiviral activities. When cytokines enter circulation, they cause typi- cal symptoms of viral infections, such as fever, lethargy, and loss of appetite.

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(continued)

Another component of this immune response are sentinel cells, which can be found in skin or mucosal surfaces. They travel through the body, looking for signs of infection. They are either dendritic cell or macrophages. Dendritic cells bind cytokines produced by virus - infected cells and respond by producing even more cytokines to amplify the immune response. In the case of many viral infections, this early reaction is enough to eliminate pathogens. If innate defenses are overwhelmed, the second - line defense is mobilized to ensure host survival.

The adaptive immune system is com- posed of specialized cells and process- es, and it relies on the clonal expansion of plasma cells to produce sufficient numbers of antibodies. This results in a delay between initial pathogen expo- sure and the production of antibodies. If the pathogens are able to reproduce rapidly in the meantime, they can dis- rupt normal body functioning and cause disease. As a result of previous expo- sure, memory cells are produced. They are produced to prevent this delay in subsequent exposures and the devel- opment of symptoms. The adaptive im- mune response begins when an imma- ture dendritic cell ingests a pathogen in

the infected tissue. It becomes activated and travels to a lymph node. The dendritic cell then matures into an antigen - presenting cell and undergoes changes that allow it to activate patho- gen - specific lymphocytes that are in the lymph nodes. Pathogen antigens are carried to the T lymphocytes. T lymphocytes stimulate B lymphocytes. A small proportion of the B lymphocytes differentiate into memory cells. They survive for many years, providing low levels of circulating antibodies. In case of a second infection with the same pathogen, the memory cells will react quickly and produce antibodies. With antibodies being produced fast, the pathogen is not able to reproduce in sufficient amounts to cause symptoms. This means that exposure to that path- ogen does not cause disease to occur, and the individual is immune.

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Emma Somers and Alexis Mpanga—LVI

A vaccine is a suspension of antigens that are intentionally put into the body to create artificial active immunity, with active immunity being immunity to a pathogen following an exposure to said pathogen. When the body is exposed to a pathogen, B lymphocyte cells (a type of white blood cell) create antibodies, which help to destroy or neutralise the pathogen. (Antibodies are proteins that are capable of binding to sites on the pathogen ’ s surface called antigens.) When B cells encounter a pathogen, they create memory cells in addition to antibodies. Memory cells are a type of B cell produced following the primary infection that can recognize the pathogen. Memory cells can survive for decades, waiting within the body until the pathogen invades again, and when the body is exposed to the pathogen for a second time, the immune response is faster and more robust. Noradrenaline is a type of neurotransmitter found in the same nervous system as the hormone adrenaline. This works together with adrenaline to create the ‘ fight or flight ’ response. Immunity does not happen immediately after disease exposure. It can take days or weeks after the first exposure for active immunity to develop, however, once it does, the protection can last an entire lifetime. Highly effective vaccines will usually last a lifetime. This is because memory cells can recognise the pathogen, if the live version ever enters the body, and quickly produce antibodies to combat it. Usually, the response is so fast that it may result in a little discomfort or no noticed change to the individual. Less effective vaccines will often need subsequent injections, or top - ups. When many people in an area or in a community are vaccinated, the pathogen will find it diffi- cult to circulate, as most of the people it encounters are immune. The more people are vac- cinated, the less likely other people, who are unable to be protected by vaccines, are at risk of being exposed to the harmful pathogens. Often, the types of people who cannot receive vac- cines have underlying health conditions, such as HIV or allergies to components of vaccines, and the vaccine would risk them harm. In this case they must rely on herd immunity to be pro- tected. Vaccines can cause side effects, just as any medication can. Most side effects from vaccination are mild, such as soreness, swelling, or redness at the injection site. Some vaccines are associ- ated with fever, rash, and achiness. Serious side effects are rare but may include seizure or life -

threatening allergic reaction. Often, long term side effects of vaccines are un- known. The Covid - 19 vaccine, for ex- ample, does not have much research and information into the long - term side effects of the vac- cine, as the virus has not been a cause for concern for very long and the vaccine is a recent product.

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Continued

What is mRNA and how is it useful as a vaccine?

Messenger RNA, shortened to mRNA, has a structure similar to DNA, however they are not the same. The role of mes- senger RNA is to form a copy of the ba-

ses on one of the two strands of a DNA molecule in a process known as transcription. This all happens in the nucleus; the mRNA then leaves the nucleus and serves as instructions for the synthesis of proteins in the cytoplasm. As previously mentioned, most vaccines today are made up a weakened pathogens or parts of one which give us active immunity, mRNA vaccines provide immunity in a slightly different way. These vaccines contain mRNA with the necessary genetic information to make bits of these viral proteins, which triggers an immune response and provides active immunity. Exam- ples of mRNA vaccines include the Pfizer and Moderna, which are two of the most recent Covid vaccines. mRNA vaccine technology is not a new feat however, due to its single - stranded structure mRNA is a fragile molecule that is difficult to deliver to our cells. The issue of their stability has been overcome much more quickly due to the urgent need for a Covid vac- cine.

Conventional vaccines

mRNA vaccines

Most vaccines against viral diseases are made from viruses grown in mam- mal cells. The process of extracting, adapting, and shipping them can take months, which is problematic if there is immediate demand for the vac- cine. There are hazards associated with growing large batches of virus, such as contamination.

The RNA is made from a template in a lab from an electronic sequence that can be sent across the world instantly by computer. It takes roughly a week to produce an experimental batch of mRNA vaccines.

Production time

Only small quantities of virus are needed for gene sequencing and testing the vaccine.

Biosafety

Immune response The antigen is injected into the body. As soon as the body recognises it as a non - self - cell, the immune system pro- duces specific antibodies to neutralise it.

RNA enters the cells where it provides instructions to produce antigens. The body then recognises the antigens and produces antibodies to fight them.

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Anton Myachin—UVI

Vaccinations have been heavily discussed in the media recently, and two very clear sides have been formed. Those who are “ anti - vax ” and the rest of the world. Anti - vaxers have been criti- cised for their thoughts and beliefs, and I would like to bring some context to them. Firstly, vaccines have been known to cause serious and sometimes even fatal side effects. Ac- cording to the CDC every vaccine carries a chance of a life threatening allergic reaction (anaphylaxis). Furthermore seizures, comas and permanent brain damage, have all been linked with vaccinations due to mercury being used in their production. In the description of

each flu virus vaccine, it states: a small pos- sibility exists that the influenza vaccine is di- rectly linked to Guillain - Barré Syndrome a disorder where one ’ s immune system attacks the peripheral nervous system. Another ma- jor belief is that vaccines cause autism. This was first claimed after a 1998 scientific paper was released conducting a test with 12 chil- dren who received the MMR vaccine, showed that 8 developed regressive devel- opment disorder and several developed gas- trointestinal symptoms. [ Editor ’ e note: This paper has since been entirely discredited, and the scientific consensus is that there

is no link between the MMR vaccine and autism] .

New vaccines come with inevitable new resistance. Due to the high tech world that we live in, social media is a forum to spread propaganda. It has been reported that 31 million people fol- low anti - vax groups on Facebook, with another 17 million people subscribing to similar ac- counts on YouTube. With news of new COVID19 vaccines, never have we seen such contro- versy amongst the whole connected population. The Medicines and Healthcare products Regu-

latory Agency (MHRA) has been warning the government about the anti - vaccine rhetoric: they say “ We fear that the anti - vax movement could derail the coronavirus vaccine pro-

gramme. ” Most of the anti - vax claims are false, unsupported, and sometimes even comical, however they undermine the vaccine program as fewer people result in taking it. The govern- ment and countless other legitimate organisa- tions have made countless reassurances, but this is not sufficient for some people. Educa- tion and further transparency by large healthcare institutions is required to minimise the number of anti - vaxers.  

A paper published in Nature earlier this year mapped online views on vaccines. The author concluded by warning that the anti - vax movement will overwhelm pro - vaccination voices online within a decade. If this came to pass, the consequences would be far beyond than COVID19.

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Ruby Freeland—LVI

During these bizarre times it feels for many people that a vaccine would allow the slow progression to a certain normal- ity that we are all so desperate to get back. However, for many, the vaccine proposes a new sense of concern and is something that should be avoided.

In 2020 the WHO identified ‘’ vaccine hesitancy ’’ as one of the top ten heath threats in the world. Furthermore, it seems that most of the scepticism surrounding vaccinations began from a discretised study. In 1998 a study by Andrew Wakefield into the measles, mumps and rubella (MMR) vaccine claimed to find a correlation between the vaccine and autism. It ’ s important to note that the study was discredited in 2012 because several elements of it were found to be incorrect and Wakefield was stripped of his medical licence in May 2012. New findings show that vital parts of the study were wrong and found evidence of deliberate fraud in the publica- tion. However, as a result of the initial publication, uptake of the MMR vaccination dropped to 80% in the late 1990s and early 2000s and has taken years to recover. Furthermore, in the age of social media, fake news and propaganda, there are constant and persistent false claims about vaccines. Theories go as far as suggesting that a Covid vaccine

will alter the patient ’ s DNA and that you essentially be- come a genetically modified human being. The Pfizer vaccine, like many other Covid Vaccines is a RNA in- jection. Instead of the traditional vaccine where they inject weakened quantities of the virus, it is a strand of RNA is injected into the body. This then produces a coronavirus spike protein which is recognised by the immune system and then it is able to produce antibod- ies in preparation for the potential fight against infec- tion.

A more plausible concern is that the vaccine may have been developed too quickly. Vaccines can take years to be crafted and perfected to insure they perform correctly and are safe for public use. However, the Covid 19 vaccine has, by its nature, had to be developed at a record pace. To add to this pharmaceutical companies are aware of the profit that can be made from the vaccine due to the demand. However, what many people are not aware of is that though this virus is new scientists have the research from SARS and MERS which are from the same family of coronaviruses. Covid vaccines must also meet the same regulatory standards as all other medicines and have had much more financial aid and readily available resources. By mo- bilising more human resources scientists are able to analyse results from previous studies and map out the next stages of the process simultaneously, further increasing the speed. While there is still some cause for concern regarding the speed at which the vaccine has been produced it would allow a global push towards herd immunity. This is a vital step in returning to the normality of before the pandemic.

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Creative Writing by Mashia Jaafari—UVI

It was a nice day in the simplest sense; one of those days where you feel that nothing could go wrong, as if the golden glow of the sun or the melodic chirping of birds could somehow protect you from the harsh realities of life. Midday approached and the park became increasingly crowd- ed, the thick patches of grass disappearing under a façade of colourful picnic blankets and sun bathers who hoped they could use this opportunity to perfect their pre - summer tan. Numerous picnic baskets, all filled to the rim with an assortment of delicacies, were scattered across the land and in one of those baskets in particular there was an egg. A simple brown egg, common and unspectacular, appearing completely harmless to the humans that were unaware of the fam- ily of bacteria frantically multiplying within it. This seemingly normal egg had not been cooked properly; the hasty rush in the morning - caused by the intention of getting an acceptably close parking space - had meant that it was taken out of the water prematurely, before the high tem- peratures had the chance to completely eradicate this population salmonella bacteria.

Finally, as the sun asserted its unquestionable dominance in the centre of the sky and the surrounding plants began tran- spiring more and more quickly, it became universally clear that it was time for lunch. In response to this supposed sign of na- ture, a large hand eagerly swung open the lid of the picnic basket, expertly extracting from it none other than the afore- mentioned egg. It sat comfortably in the man ’ s rather large hand, which had by now crushed and removed the last of the coarse remnants of the egg ’ s harsh exterior. The man careful- ly guided it into his mouth and chewed slowly, enjoying the fa-

miliar taste that he was accustomed to from his usual breakfasts. Once he felt that the chewing sufficed and the protease enzymes in his saliva had successfully done their job, he swallowed. The epiglottis snapped shut in a rapid reflex action and the components of the egg moved down the oesophagus, being nudged down faster by the drink of water the man took to refresh himself. The bacteria were in. This concoction of protein and fat reached the stomach and was greeted by the unforgivingly low pH of hydrochloric acid. Usually at this point any bacteria would have fallen to the mercy of this acid, but not these bacteria. They have developed adaptive mecha- nisms that allowed them to survive the acidic conditions of the stomach and happily passed into the man ’ s intestinal tract. Once in the small intestine these salmonella bacteria felt at home, quickly and relentlessly invad- ing the lining of the small intestine. The bacterial endotoxins quickly went to work, inducing symptoms of the disease such as vomiting and diarrhoea. As the man woke up the next morning, his awful sunburn was not the only thing troubling him; he felt nauseous and a terrible urge to go to the toilet. Luckily, the bathroom was not far away, and he managed to drag himself onto the toilet before things got messy. As relieving as that was, even better was the fact that a non - specific response was even closer. Mast cells and basophils detected the polysaccharide part of lipopolysaccharide endotoxins and quickly released histamines. These histamines induced vaso- dilation leading to a local increase in temperature. They also caused the walls of the capillaries in the lining of the small intestine to become leaky by making the cells separate, thereby allowing some phagocytes into the area. Soon after this, the hypothalamus raised the body temperature to 38 degrees inducing a fever. The man felt very ill indeed, but this was even worse for the bac- teria – their division slowed while the phagocytes could work more efficiently. As soon as the phagocytes entered the infected tissue, they engulfed these treacherous pathogens, enclosing them into a phagosome which then fused with a lysosome. Fortunately, the hydrolytic enzymes within the lysosome brought the engulfed bacteria to their doom.

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Continued

The glory soon wore off because the non - specific response knew that it could not de- feat this pathogen alone. A stronger force was needed; something bigger, stronger and more specific. This is when the specific im- mune system came to save the mans life. A macrophage which had digested a pathogen bound fragments of the bacterial antigens with a major histocompatibility complex pro- tein and this was displayed on the surface of the macrophage, so it became an antigen presenting cell. With a sense of urgency this macrophage migrated to a lymph node, hop- ing that it would find a T cell which could

solve all of their problems. Days went by but to the macrophage it had seemed like years, the man ’ s health was deteriorating, and the necessary T cell was still not found. Just when the APC thought all hope was lost, it felt something attach to its surface. There it was, the T cell with the complementary receptors! Without further hesitation the T cell was activated and divid- ed by mitosis to form clones of T helper cells, T killer cells and T memory cells. While all of this was happening, somewhere near the small intestine a B cell with complemen- tary antibodies had attached to and digested one of the bacteria. It also became an antigen presenting cell and began migrating to the lymph node. Once at the lymph node, the B cell waited patiently until finally it happened, an activated T helper cell with complementary recep- tors attached to the antigen presenting B cell and released cytokines. These cytokines activat- ed the B cell, initiating clonal selection in which the B cell divided to produce B effector cells and B memory cells. The effector cells quickly differentiated to become plasma cells. That day the rough endoplasmic reticulum and the Golgi apparatus of the plasma cells worked longer shifts than ever before, tirelessly transcribing, translating and modifying until they were releas- ing sufficient antibodies into the blood. These antigens were like the super medicine the man needed. A sense of hope was restored. The antibodies attached to the pathogens and forced them to clump together in the terror which was agglutination and the phagocytes ravenously digested them in large numbers. The bacteria ’ s game of hide and seek was put to a stop as the antibodies opsonised the bacteria, making them visible to the phagocytes who then feasted on the blood of the helpless salmonella bacteria. At the same time, cells which had already fallen to the bacteria were respectfully executed by their T killer cell comrades, knowing all to well that their death would be the only way that life could continue. With this in mind they sacrificed themselves without hesitation and saluted the T killer cells as the perforins began to take ef- fect, creating holes in their membranes and leading to the inevitable lysis of these brave cells. Finally, it looked like the battle had been won, the bacteria had been eradicated without mercy. Unfortunately, he body had also lost a fair few soldiers who lay in beds of white pus. The man felt better; his fever had lowered, the diarrhoea and the vomiting disappeared, and he no long- er felt nauseous. He had escaped the wrath of the salmonella on this occasion but who knows if he will escape again next time? Rest assured he will once again defeat the bacteria in any future battles because his body now has trained soldiers, ready to fight specifically these indi- gestible bacteria if they dare to return. The second battle will be legendary, an easy victory for the body, and the man will live to see another day.

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—An SESC Applied Science project

by Douggie Campbell— 4 th Form

Single use plastics from Covid - 19 are a necessary yet extremely harmful part of this pandemic. I wanted to see if I could measure the impact that one mask, wipe or glove could have on the envi- ronment, and how in great numbers this impact could be extremely harmful. To measure how biodegradable Covid waste is, I left different types in compost for a period of 50 days. These results allowed me to predict how long these would take to fully decompose:

Item

Time to fully decompose

Gloves

1250 days (3 years, 4 months) 1000 days (2 years, 8 months) 164,250 days (450 years)

Wipes

Masks*

How biodegradable is Covid waste?

Covid waste is extremely harmful to our environment and can have a great negative effect on our planet. Disposable masks take 450 years to decompose, while wipes we use everyday at school take 3 years at least to decompose. It clearly is not made to disappear, and there is no reason for people in everyday life to have such a negative impact on the planet.

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