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Influenza pp
1. Department of Molecular Virology and MicrobiologyADITYA BHATT
MOLECULAR
VIROLOGY OF H1N1
The H1N1 Influenza Pandemic
PRESENTATION BY:ADITYA BHATT
2. Department of Molecular Virology and Microbiology
What is Swine Flu?
• A new type of flu that infects people
• Like regular flu, it is a respiratory disease
that causes fever, aches, coughing, runny
nose, chills, and tiredness
• More likely than regular flu to cause
vomiting and diarrhea
• Contagious disease that spreads from
person to person through microscopic
particles that enter the air from coughs
and sneezes of infected people
• Caused by a new type of flu virus
3. Department of Molecular Virology and Microbiology
What is a Flu Virus?
• Viruses are microscopic particles that
contain genetic material (DNA or RNA)
surrounded by a protein coating
• Viruses must infect cells to make more
copies of themselves
• Flu – or influenza – viruses have RNA as
their genetic material
• Flu viruses have eight pieces of RNA that
hold the instructions for making more
copies of itself
4. Department of Molecular Virology and Microbiology
Why is it called “Swine” Flu?
The flu can cause disease not only in humans, but also in
animals like pigs and birds
The new virus is made from pieces of flu viruses that infect
pigs from North America, pigs from Eurasia, and pieces
from human and bird flu viruses that were all mixed
together
Scientific name is Influenza A/H1N1
Eurasian
North
American+ + +
5. Department of Molecular Virology and Microbiology
What does “Influenza A/H1N1” mean?
• Three types of flu viruses – A, B, and C
• The “A” type is the most dangerous
• Divided into subtypes based on two proteins that
spike out of the virus
• H – or hemagglutinin – 16 versions, needed for
virus to enter cell
• N – or neuraminidase – 9 versions, needed for
virus to leave cell
• H1N1 has version 1 of “H” protein and version 1
of “N” protein
• Virus with version 3 of H and version 2 of N is
called… H3N2
6. Department of Molecular Virology and Microbiology
How are new flu viruses created?
• Two different flu viruses infect one cell and are
mixed together into a new virus
7. Department of Molecular Virology and Microbiology
Viral proteins:
1. Hemagglutinin(HA).
2. neuraminidase (NA).
3. matrix 1(M1).
4. matrix 2 (M2).
5. nucleoprotein (NP).
6. polymerase acidic protein (PA).
7. non-structural protein 1 (NSP1).
8. non-structural protein 2(NSP2).
9. acidic
8. Department of Molecular Virology and Microbiology
Viral proteins:
9. polymerase basic protein 1 (PB1).
10. polymerase basic protein 2 (PB2).
11.polymerase basic protein 1 – F2.
9. Department of Molecular Virology and Microbiology
How is swine flu different from regular flu?
• Regular flu viruses that occur each season
undergo small genetic changes
– Called drift
– Reason that flu shots are needed each year
• Swine flu is an example of a pandemic flu
formed when large genetic changes
happen
– Called shift
– Produces a new virus with a new combination of
“H” and “N” proteins
– People have little immunity or defense against
the new virus
16. Department of Molecular Virology and Microbiology
Major classes of anti-influenza
drugs
• The anti-influenza drugs are usually
classified
according to their target in
the viral life-cycle.
• Such antiviral molecules are
particularly used as inhibitors of the
following processes: 1.attachment of
the virus to host cell receptors,
endocytosis and fusion of viral and cell
membranes
17. Department of Molecular Virology and Microbiology
Major classes of anti-influenza
drugs
• replication and transcription of the
viral genome.
• synthesis of viral proteins
• assembly of the viral progeny and
release of the new virions into the
outside environment.
18. Department of Molecular Virology and Microbiology
Are there drugs or vaccines?
• Two drugs work against the new H1N1 swine
flu – Tamiflu and Relenza.
• Drugs block the action of the “NA” protein .
• Their use is not needed for all patients, but is
likely to be used in patients at high risk.
• A vaccine to prevent swine flu has been
developed and tested.
• Limited doses of the H1N1 vaccine are
currently available.
• Priority for the H1N1 vaccine is given to high-
risk groups, including school-age children.
19. Department of Molecular Virology and Microbiology
What are scientists doing about H1N1?
• Monitoring the spread of the virus
• Finding out which people are at highest
risk
• Analyzing the genetic makeup of the virus
to get an idea of how dangerous the virus
is or if it is changing
• Developing and testing vaccines that can
safely prevent infection by H1N1
• Studying the immune responses of
infected and vaccinated people
20. Department of Molecular Virology and Microbiology
Summary
• Swine flu is caused by a new flu virus – the
2009 H1N1 virus - that never existed before
• H1N1 contains pieces from pig (swine) flu
viruses
• Most people do not have natural protection
against the new H1N1 virus, so many people
will get infected
• H1N1 has spread around the world faster
than any other virus
• Most people recover completely without
medicine, but treatment can shorten the
length of sickness.
This slide presentation was prepared by Christine Herrmann, Ph.D., and reviewed by Dr. Paul Glezen and Dr. Tony Piedra, of the Department of Molecular Virology and Microbiology at Baylor College of Medicine. It is intended as an educational resource for middle and high school classrooms. Additional information about influenza and other emerging infectious diseases can be found on the Departmental website at http://www.bcm.edu/molvir/eidbt/eidbt-mvm-flu.htm.
The information in this presentation was current as of November 1, 2009. As the situation has the potential to change rapidly, check with the websites of the Centers for Disease Control and Prevention (http://www.cdc.gov/h1n1flu/) or the World Health Organization (http://www.who.int/csr/disease/swineflu/en/index.html) for the most up-to-date information and guidelines.
Image: Stained transmission electron micrograph of an influenza virus particle. Courtesy: CDC
Image: Stained transmission electron micrograph of an influenza virus particle. Courtesy: CDC
In the card analogy of the previous slide, shift is like changing from a red card to a black card (hearts to spades), while drift is more like changing from one red suit to another (hearts to diamonds).
Image Courtesy: CDC
High-risk groups include health care and emergency workers, pregnant women, everyone between the ages of 6 months to 24 years, adults up to age 64 with medical problems, and people caring for infants under 6 months old.
The stock used to produce the H1N1 vaccine has grown more slowly than stocks used to produce seasonal flu vaccines, slowing H1N1 vaccine production. Therefore fewer vaccine doses became available in October than anticipated. Sufficient supplies are expected to become available later in the flu season.
The H1N1 vaccine is produced in the same way as seasonal flu vaccines, so the risk is expected to be similar to that of regular flu shots. It is important to weigh the potential risks of a flu vaccine with the benefits of preventing a disease that can be deadly.
