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Jenny Yu
Professor LeFebvre
Cluster 7: Biomedical Sciences
July 27, 2015
Influenza: the Coming Pandemic
Everyday single day, there is a chance of becoming infected with the influenza virus.
Even those who take precautionary measures are vulnerable. It is nearly impossible
to avoid this respiratory disease due to the fact that it is highly contagious. In order
to understand how to create vaccinations, scientists must have a clear
understanding of the virus’ molecular structure. Furthermore, becoming familiar
with the different types of influenza viruses is essential, for specific subtypes and
strains can trigger either the seasonal influenza or can lead to a devastating
pandemic.
Every year, millions of people are attacked by a contagious infection. Weakness
consumes the body, and, when severe enough, the body collapses. This infection acts as an
annual tradition; it is the influenza virus. Influenza, often referred to as the flu, is a viral
infection that causes critical damage to the respiratory system. Many innocent bystanders
become infected once they are within the range of a contaminated area or an ill host. The
virus can be introduced to a new host simply through a mere cough or sneeze; tiny droplets
are transported directly onto another host. In addition, the “virus can survive on hard,
nonporous surfaces (e.g., stainless steel, hard plastic) for 24 – 48 hours and on porous
materials (e.g., cloth, paper) for < 8 – 12 hours in ambient temperatures (1). Virus
persistence on surfaces increases up to 72 hours when those surfaces are moist or wet (2)”
(“Interim Guidance” para. 4). Every year, the flu demonstrates its dominance, especially
during the colder seasons, but even so, it can be obtained during any time of the year if
precautionary measures are not taken. Because this viral infection is contagious, it is
essential to know what is happening on the molecular level, which type of influenza virus
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one has been diagnosed with, and what the difference is between the pandemic and
seasonal influenza.
In order to understand how the infection intrudes the body, scientists must take a
closer look at the molecular structure of the virus. First, it is important to know what family
the virus comes from. According to Molecular Expressions, “the virus is comprise[d of]
their own viral family, Orthomyxoviridae” (“Molecular Expressions” para. 3). The virion,
the infective particle outside a host cell, has a spherical shape. More specifically, its
diameter ranges from 80 to 120 nanometers. The virion’s envelope is made up of two
proteins. Eighty percent of the envelope is covered with hemagglutinin spikes.
Hemagglutinin, usually abbreviated as HA, is the protein that is capable of attaching the
virus to a targeted host cell. The rest of the envelope is covered with neuraminidase spikes.
Neuraminidase, usually abbreviated as NA, is the protein that is responsible for producing
new virus particles from a specific host cell. Furthermore, within the envelope is an
antigenic matrix protein lining. As for the influenza genome, there are as many as eight
single-stranded RNA. Influenza types A and B both have eight RNA strands, but Influenza
type C has seven RNA strands. Adding to that, the RNA contains nucleoproteins that are
formed into “a helical ribonucleoprotein form, with three polymerase peptides for each
RNA segment” (“Molecular Expressions” para. 4). Understanding the basis of viral
infections by looking into the molecular level is an essential component, as well as
becoming familiar with all existing types of influenza viruses.
When diagnosed with influenza, it is important to know which type is infecting the
body. There are a total of three different types of viruses, which are categorized into three
groups: A, B, and C. The first type is Influenza type A; the virus is split amongst the two
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main proteins: hemagglutinin and neuraminidase. As of now, there are up to eighteen
known hemagglutinin subtypes and eleven neuraminidase subtypes. Because of this, there
are a variety of combinations in existence (“Influenza Type A Viruses” para. 2). Each
subtype has the ability to infect a certain host. For example, wild aquatic birds are
vulnerable to almost all known subtypes, excluding H17N10 and H18N11. There are also
other known subtypes, such as the avian, equine, swine, canine, etc. From birds to humans,
this illness attacks a variety of animals. The avian influenza, also known as the bird flu, has
the potential to cause severe damage, especially the H5N1 virus. There are many avian
influenza viruses such as H5N2, H7N1, H7N2, H7N3, H7N4, H7N7, H9N8, and H5N1. There
have been many recorded outbreaks regarding these subtypes. Currently, H5N1 holds the
most potential to creating “epidemics in several regions of the world… pandemic[s] of this
infectious disease is expected [in the future]” (Wiwankitki XV). In addition to the avian
subtypes, there are equine subtypes. The equine subtypes, H7N7 and H3N8, “target… the
horse's respiratory system; the influenza virus damages the lining and mucous membranes
in the animal's respiratory tract in a rather short period of time, with the incubation period
being only one to three days after infection” (“Flu Viruses in Horses” para. 1). Likewise, the
equine subtypes and canine subtypes are very similar. The canine subtypes, H3N8 and
H3N2, infect dogs and cats; they were first discovered in the year 2007 in South Korea.
According to Centers for Disease Control and Prevention, “an investigation showed that this
respiratory illness was caused by the equine influenza A H3N8 virus” (“Key Facts about
Canine Influenza” para. 4). To this day, there have been no signs of this subtype causing
infections in humans. Although, scientists do worry that they will have the ability to cause a
pandemic in the future, for humans are not immune to this. In addition to that, the swine
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subtypes have caused a major uproar in the past years. The swine subtypes, H1N1, H3N2,
and, H1N2, were first found in pigs. Studies have shown that the H1N1 strain has the ability
to affect humans as well. In 2009, there was a pandemic regarding this virus. As the years
have passed, new vaccines have been created. Today, the swine flu is a seasonal type of
influenza. When a human becomes infected with the swine flu, the name of the virus
changes into variant viruses. The purpose of variant viruses is to distinguish the virus
between animal and humans; the letter “v” is applied. For example, H1N1 would be
denoted to H1N1v. Like the Type A Influenza, the Type B Influenza acts very similar.
However, instead of being categorized into subtypes, they are categorized into strains. It is
less common to become infected with Influenza Type B when compared to Influenza Type
A. Once the host becomes ill, similar symptoms result; weakness and pain consume the
respiratory system. Not only that, but the body may feel fatigued, develop body aches, and
result in an alarming fever. The fever may reach as high as 106° Fahrenheit. Furthermore,
critical damage may result if the illness is not treated properly, for the host is exposed to a
higher risk of developing dangerous complications such as bacterial pneumonia,
Encephalitis, Myositis, Reye's syndrome, and more (“Influenza B” 1). Unlike Type A and B,
Influenza Type C differs, for it is milder. Those who become infected by C typically do not
become very ill in comparison to A and B. In fact, health organizations stress very little for
C. They predict that it holds no potential in triggering future epidemics (“Different Types of
Flu” 2). All in all, the significance of each type of influenza virus is critical; having a general
understanding of which type(s) bring about the seasonal influenza and which type(s) have
the potential of initiating a pandemic is crucial.
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Moreover, there is a large difference between the seasonal and pandemic influenzas.
First, it is important to note that the influenza strains are constantly changing. They slowly
manipulate themselves; this allows the new strains to infect a host whose immune system
is vulnerable. Since the immune system would be unfamiliar with the new strains, it would
be simple for infection(s) to quickly take place. As previously stated, Influenza Types A and
B contribute to the seasonal flu. During the colder seasons, it makes its visit. Those who
catch this typically have some sort of immunity towards it, whether it be a vaccination or
simply because s/he has had the respiratory infection beforehand. The seasonal influenza
usually results in symptoms such as a fatigued body, aching muscles, fever, sore throat,
cough, runny nose, etc. In the USA, there are approximately 36,000 deaths per year. As for
the pandemic influenza, Influenza Type A is the known cause of this. Those who become
infected are overwhelmed. Because there is no vaccination, and since there has been either
no or a small amount of pre-existing exposure to this strain, the immune system is forced to
become independent. During the twentieth century, there were a total of three recorded
outbreaks. In the year 1918, the death toll was estimated to be approximately 500,000.
Factors such as exhausted health systems, a low resource of antiviral medications, and
more, encourage the body to develop a range of mild to severe complications. All of these
factors contribute to support fatality; thus, creating a rise in the death rates (Earle 1).
Needless to say, the seasonal and pandemic influenzas contrast greatly.
Influenza, a serious virus that causes immense damage to, not only the respiratory
system but also overall general health, is a severe infection that has the power to weaken a
large population. In order to fight off the infection, it is important to be aware of the
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molecular configuration, which types of influenza viruses, subtypes, and strains affect the
body, and how to differentiate between the seasonal and pandemic influenza.
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Works Cited
Earle, Dp. "A Case of Flu: Immune Targets." Biochemical Education 17.3 (1989): 156.
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