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Influenza and the Swine Flu
Derrick Dill and Aaron Mix
The objective of this website is to act as resource page to help people understand what the seasonal influenza virus is, what the newly discovered H1N1 (Swine Flu) virus is, and how they are different. We will examine the structural properties of the influenza virus, how one becomes infected with the influenza virus, and how we can treat/prevent the influenza virus. During a time when this virus is circulating throughout the world, and is the topic on many television news shows, it is important to know how the influenza virus and H1N1 virus affect us as humans.
What is a Virus?
Viruses are known for their simple structural organization and their mechanism of multiplication. The characteristics and properties of a virus are:
Contain a single type of nucleic acid, either DNA or RNA
Contain a protein coat
Sometimes enclosed by an envelope of macromolecules that surrounds the nucleic acid
Multiply inside living cells by using the synthesizing machinery of the cell
Cause the synthesis of specialized structures that can transfer the viral nucleic acid to other cells
In(flu)enza - The Flu
Influenza is a infectious disease that is affects birds and mammals and is often referred to as "The Flu".The flu is a contagious respiratory illness caused by influenza viruses.
Influenza is highly contagious and is more common during the colder months of the year. In the United States alone, approximately 25 to 50 million people contract influenza each year and an estimated 50,000 to 70,000 Americans die annually of the flu.
The Orthomyxoviridae are a family of RNA viruses that include Influenza A, B, and C.
Influenza virus A is the cause of all flu pandemics, and infect humans, mammals, and birds - Spanish Flu (40 million+ deaths!)
Influenza virus B infect humans and seals - less common then A - mutates much slower (2-3 times), making immunity possible
Influenza virus C infect humans and pigs - least common, can cause severe illness in children
Influenza Virus Structure
The Viruses particles are usually spherical or ovoid (like an egg or ellipse) in shape and are usually 80-120 nanometers in diameter.
The Influenza virus is an enveloped virus that develops its lipid bilayer from the plasma membrane of its host. Scattered in the lipid bilayer are two integral membrane proteins:
Approximately 500 molecules of
") and some 100 molecules of
Two different varieties of spikes are embedded in the envelope
. About 80 percent of the spikes consist of Hemagglutinin, hemagglutinin is a protein that functions in the attachment of the virus to the host cell. The remaining (~20 percent) of neuraminidase
is thought to be used to release newly produced virus particles from the host cell
. On the inside of the Influenza virus is a antigenic protein lining which contains eight pieces of single stranded RNA
(A and B forms only; influenza C has 7 RNA segments). The RNA is packaged with nucleoprotein into a helical ribonucleic form, with three polymerase peptides for each RNA segment.
The symptoms of the flu are similar to those of the common cold, but tend to be more severe.Symptoms can happen quickly, and can start suddenly after one or two days of infection. Symptoms include: Fever, headache, fatigue, muscle weakness and pain, sore throat, cough,
extreme coldness and fever, Reddened eyes, skin (especially face), mouth, throat and nose, Irritated watering eyes
Influenza can be spread in three main ways: by direct transmission when an infected person sneezes mucus into the eyes, nose or mouth of another person; through people inhaling the aerosols produced by infected people coughing, sneezing and spitting; and through hand-to-mouth transmission from either contaminated surfaces or direct personal contact, such as a hand-shake.
The H1N1 Virus (The Swine Flu):
April 2009 H1N1 Virus
Swine Influenza (swine flu) is a respiratory disease of pigs caused by type A influenza virus that regularly causes outbreaks of influenza in pigs. Swine flu viruses cause high levels of illness and low death rates in pigs. Swine influenza viruses may circulate among swine throughout the year, but most outbreaks occur during the late fall and winter months similar to outbreaks in humans. The classical swine flu virus (an influenza type A H1N1 virus) was first isolated from a pig in 1930.
The H1N1 (referred to as “swine flu” early on) is a new influenza virus causing illness in people. This new virus was first detected in people in the United States in April 2009. Other countries, including Mexico and Canada, have reported people sick with this new virus. This virus is spreading from person-to-person, probably in much the same way that regular seasonal influenza viruses spread.
Why is this new H1N1 virus sometimes called “swine flu”?
This virus was originally referred to as “swine flu” because laboratory testing showed that many of the genes in this new virus were very similar to influenza viruses that normally occur in pigs in North America. But further study has shown that this new virus is very different from what normally circulates in North American pigs. It has two genes from flu viruses that normally circulate in pigs in Europe and Asia and avian genes and human genes. Scientists call this a “quadruple reassortant” virus.
Prevention & Treatment
Is there a vaccine for swine flu?
Vaccines are available to be given to pigs to prevent swine influenza. There is no vaccine to protect humans from swine flu. The seasonal influenza vaccine will likely help provide partial protection against swine H3N2, but not swine H1N1 viruses.
Are there medications available to treat swine flu infections in humans?
There are four different antiviral drugs that are licensed for use in the US for the treatment of influenza: amantadine, rimantadine, oseltamivir and zanamivir. While most swine influenza viruses have been susceptible to all four drugs, the most recent H1N1 influenza viruses isolated from humans are resistant to amantadine and rimantadine.
Take these everyday steps to protect your health:
Cover your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the trash after you use it.
Wash your hands often with soap and water, especially after you cough or sneeze. Alcohol-based hand cleaners are also effective.
Avoid touching your eyes, nose or mouth. Germs spread this way.
Try to avoid close contact with sick people.
Stay home if you are sick for 7 days after your symptoms begin or until you have been symptom-free for 24 hours, whichever is longer. This is to keep from infecting others and spreading the virus further.
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Microbiology: An Introduction
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