Infectious Diseases Unit Copyright © 2010 Ryan P. Murphy

"The first chapter of The Hot Zone is one of the most horrifying things I've read in my whole life--and then it gets worse. That's what I keep marveling over: it keeps getting worse. What a remarkable piece of work." --Stephen King Copyright © 2010 Ryan P. Murphy

Ebola virus

Infectious Diseases will include Viruses Bacteria Parasites Copyright © 2010 Ryan P. Murphy

Black Plague (also called Bubonic Plague) In four years, a bacterium killed 20 to 30 million Europeans. Copyright © 2010 Ryan P. Murphy

In the Extreme East, China dwindled from 123 million inhabitants at the beginning of the 13th century to just 65 million during the 14th century, because of the plague. You do the math… Copyright © 2010 Ryan P. Murphy

In the Extreme East, China dwindled from 123 million inhabitants at the beginning of the 13th century to just 65 million during the 14th century, because of the plague. You do the math… 58 Million Dead Copyright © 2010 Ryan P. Murphy

Copyright © 2010 Ryan P. Murphy

Spanish Flu –WWI (virus) (40 Million Dead Worldwide) Pandemic -Note: The Spanish Flu is not as well known as it occurred during war time and countries kept death toll a secret. Copyright © 2010 Ryan P. Murphy

Since 1914 to 1977 Smallpox (Bacterium) Killed 300 to 500 million people.

Since 1914 to 1977 Smallpox Killed 300 to 500 million people.

The smallpox virus. Copyright © 2010 Ryan P. Murphy

Polio (Virus)– Killed and Crippled Millions until about 1958

Another great vaccine saved millions from Polio in 1955.

HIV (Virus) – 60 Million Currently Infected

Malaria (Plasmodium Parasite) is found in 500 million people Malaria (Plasmodium Parasite) is found in 500 million people. 300 million cases are very severe. Hundreds of million die. Most of which are children. Copyright © 2010 Ryan P. Murphy

Gonorrhea and syphilis (Bacterium) 62 million people worldwide are affected. Most are 15 to 29 years of age. Copyright © 2010 Ryan P. Murphy

Pneumonia (Bacteria): It kills 3.5 million people each year.

2 million people die annually of tuberculosis. About 150 million people are estimated to have died of TBC since 1914.

Mad Cow Disease

Mad Cow Disease Prions (virus like protein – smaller than virus)

Viruses infect just about every type of life form.

How do they spread? How fast can they spread? Usually through fluid exchange Blood Saliva Mucus Wastes LET’S EXHANGE FLUIDS!!!

Section 18.1 Summary – pages 475-483 Viral Structure A virus has an inner core of nucleic acid, either RNA or DNA, and an outer protein coat called a capsid. Capsid Some relatively large viruses have an envelope, surrounding their capsids. Envelopes are made from the same type of materials of the cell membrane. Nucleic acid Envelope Section 18.1 Summary – pages 475-483

Lipid Envelope Nucleic Acid Protein Capsid Virion Associated Polymerase Spike Projections

Varies in size, shape and symmetry Highly impo. for classification 3 types of capsid symmetry: Cubic (icosahedral) Helical Complex 5 basic types of virus structure:

Viruses are non-living because… Viruses are not made of cells. They have no cell parts. They do not grow and develop. They do not respond to their environment Copyright © 2010 Ryan P. Murphy

Viruses COULD be considered living because… Viruses do Replicate, but only by invading living cells, not by themselves. They do Evolve / Mutate. This is why we still do not have a cure for HIV/AIDS End notes for hour 1 Copyright © 2010 Ryan P. Murphy

How do viruses multiply / infect? Two ways Lytic Infection – a virus enters a cell, makes copies of itself, and causes the cell to burst. Lysogenic Infection – host cell makes copies of virus indefinitely because the virus DNA is imbedded in the host DNA sequence

1 5 4 2 3 7 6 8 Virus attachment and entry Uncoating of virion Migration of genome 1 nucleic acid to nucleus 5 Transcription Genome replication Translation of virus mRNAs 4 2 3 7 Virion assembly Release of new virus particles 6 8

Section 18.1 Summary – pages 475-483 Lytic cycle Bacteriophage Bacterial DNA Nucleic acid Bacterial host cell B. Entry A. Attachment The bacteriophage injects its nucleic acid into the bacterial cell. E. Lysis and Release The host cell breaks open and releases new virus particles. C. Replication D. Assembly The host’s metabolic machinery makes viral nucleic acid and proteins. New virus particles are assembled. Section 18.1 Summary – pages 475-483

Section 18.1 Summary – pages 475-483 Viral Replication Before a virus can replicate, it must enter a host cell. A virus recognizes and attaches to a host cell when one of its proteins interlocks with a molecular shape that is the receptor site on the host cell’s plasma membrane. In some viruses, the attachment protein is in the capsid or in the envelope. In the T4 bacteriophage, a protein in the tail fibers recognizes and attaches the T4 to its bacterial host cell. Section 18.1 Summary – pages 475-483

Section 18.1 Summary – pages 475-483 T4 Bacteriophage Capsid Nucleic acid Tail Tail fiber Section 18.1 Summary – pages 475-483

A bacteriophage is any one of a number of viruses that infect bacteria Inject genetic material, which they carry enclosed in an outer protein capsid

Q: If you get a cold sore do you have herpes? A: Yes, Herpes Simplex, Not genital Herpes called Herpes Complex.

URGENT! Coldsores are a strain of herpes simplex. The herpes STD is a different strain of herpes called herpes complex. Copyright © 2010 Ryan P. Murphy

Herpes simplex can infect other areas besides your mouth. Copyright © 2010 Ryan P. Murphy

“Let’s be friends forever.” Lysogenic Virus – A virus that can hide inside your cells DNA until it breaks out (lytic) and then hides again. With you forever. “Let’s be friends forever.” Copyright © 2010 Ryan P. Murphy

Section 18.1 Summary – pages 475-483 Lysogenic cycle B. Provirus Formation A. Attachment and Entry Provirus Although the provirus is inactive, it replicates along with the host cell’s chromosome. C. Cell Division Bacterial host chromosome A lysogenic virus injects its nucleic acid into a bacterium. The viral nucleic acid is called a provirus when it becomes part of the host’s chromosome. LYSOGENIC CYCLE LYTIC CYCLE The provirus leaves the chromosome. The cell breaks open releasing viruses. Viral nucleic acid and proteins are made. Section 18.1 Summary – pages 475-483

The virus waits for many months, even years until conditions are right. Stress. Sun burn. Dryness. Then it strikes and looks for new host. Copyright © 2010 Ryan P. Murphy

She will now have his herpes virus in her cells for the rest of her life. Her cells will continue to copy the virus as they reproduce. Until… Copyright © 2010 Ryan P. Murphy

She will now have his herpes virus in her cells for the rest of her life. Her cells will continue to copy the virus as they reproduce. Until… Lytic outbreak Copyright © 2010 Ryan P. Murphy

Other Types of Viruses Oncogenic viruses: carry genes that disrupt the normal cell cycle of animals, which can lead to cancer (HPV virus) Retroviruses: viruses that contain RNA as their genetic material (HIV, influenza) Prions: “protein infectious particles;” abnormally shaped proteins located in the brains of animals (Mad cow disease, CWD)

Prevention & Treatment Vaccinations - made from dead or inactive viruses. Inactivated - do not replicate in the host Attenuated - viruses that have been genetically altered so they are not capable of causing the disease. Boosters - an additional dose of a vaccine to extend protection. Poliovirus

Symptoms Amount of virus Time Virus

Human T-cell Leukaemia Virus (HTLV-1) Hepatitis C virus Epstein Barr Virus Burkitt’s Lymphoma Human papillomavirus Benign warts Cervical Carcinoma Human T-cell Leukaemia Virus (HTLV-1) Leukaemia Hepatitis C virus Liver carcinoma

Prevention & Treatment Anti-viral drugs - drugs that interfere with the viral nucleic acid synthesis. These are given to infected patients. Best way to control disease is through prevention. ANTIBIOTICS are NOT useful against viruses. Photo Courtesy of CDC3

Where is the Centers for Disease Control and Prevention located? Atlanta, Georgia Moscow, Russia

World Health Organization AKA – W.H.O. Decided in 1967 to eradicate small pox the disease from the general population. This was officially accomplished in 1980, with the last known case in Somalia, 1977.

Emerging Viruses These are newly discovered viruses that are emerging in different parts of the world. They exist is isolated habitats and infect humans when those habitats are developed. Some examples include: Ebola, HIV, and West Nile.

Treatment of Viral Diseases Antibiotics do not work on viruses!! Why? Antibiotics destroy the cell walls of bacteria, but viruses are not composed of cells White blood cells