Lecture 32, 12/3; Viruses, Immunology

Here is the audio.

• • Medically important human viruses
• • HSV-1, HSV-2 → herpes, oral and genital
• • RSV → respiratory sincicial virus. Mom can give it to the baby.
• • EBV → mono and burkettes lymphona
• • VZV → chicken pox and shingles
• • HPV → human papiloma virus. Causes warts. Some strains are associated with cervical cancer. (this is why Guardisil is popular)
• • Adenovirus → upper respiratory infections, not a cold
• • HAV → Hep A virus. Fecal/oral → contaminated water/food. There is a vaccine for it.
• • HBV → Hep B virus. Blood borne or semen. Linked with liver cancer. There is a vaccine for it.
• • HCV → Hep C virus. Similar transimission to Hep B. Used to be called transfusion disease. No vaccine.
• • Rotavirus → severe diarrhea in babies and toddlers. Rotateq combats this disease.
• • Rubella virus → German measles
• • Variola virus → supposedly eradicated. Smallpox
• • Rabies virus → rabies. Bullet shaped virus. Most deadly.
• • Measles virus → MMR takes care of it
• • Influenza → old get vaccinated. Hypermutability – changes very quickly. This is why you need a flu shot every year.
• • Hantavirus - Navajo flu → Comes from little white mice.
• • CMV – Cytomegalo virus → Babies, toddlers, and AIDs patients are susceptible.
• • Rhinovirus → common cold, 120 different strains (that is why there is no vaccine).
• • Echo/Coxsackle viruses - Noro virus → Causes gastroenteritis. Cruise ship disease.
• • Mumps virus → can move to testicles in guys. MMR vaccine takes care of it.
• • St. Louis Encephalitis virus (SLE) → mosquito borne
• • West Nile → mosquito borne
• • HIV-1 and HIV-2 → takes out all T helper cells. Allows for opportunistic disease to come in.
• • HTLV-1 and HTLV-2 - human T cell lymphoma viruses → Can cause cancer.
• • AID’s related infections – sheet from handout showing diseases AID’s patients get with time.
• o Bacterial skin infections are one of the first things you see.
• o Thrush comes in (usually a good indicator of AID’s)
• o Severe athletes foot
• o PCP, histo, herpes, crypto
• • IMMUNOLOGY
• o Winter viruses are typically airborne
• • 1st line of defense – Mechanical factors
• o lysosymes – good against gram (+).
• o Organisms can’t go through the skin EXCEPT for rabbit fever
• o Mucus is sticky and holds organisms
• o Normal flora – prevent pathogens from colonizing
• • Second line of defense - Cellular factors
• o If disease comes into bloodstream white blood cells will come to do phagocytosis (discovered by Meintchnekoff). Interferon was initially up to 10,000$ a shot.
• o Inflammation – heat, redness, swelling, pain. This is the bodies way of localizing an infection.
• • Third line; antibody formation. Takes 10-14 days
• o Acquired immunity
• • Types of acquired immunity
• o Active immunity – we form the antibodies (long lasting)
• • Artificially acquired - vaccines
• Naturally acquired – infections
• • Acute or sub-acute
• o Passive immunity – someone else is forming the antibodies
• • Artificially acquired – HBIG
• • Immune globulin – immediate protection but does not last long (about a month). They are preformed antibodies.
• • Naturally acquired – HgG and IgA
• IgG is given from the mother to baby across the placenta. IgA is from mothers milk – it coats intestine of baby and prevents diarrhea in baby. Rototeq can cause this diarrhea.
• • Classes of antibodies
• o “Y” usually represents antibodies
• o IgG – the most important one, we have the most of this in our blood. 80-85% of all the antibodies we carry is IgG. Major protective antibody in blood. If you run into an antigen it is IgG that will probably attach to it. It is also the one that comes from mom to baby over placenta.

Lecture 26, 11/12 (Maybruck 11); Viruses

Audio for lecture on 11/12 is available here.

• • Slide 1 handout from 11/9
• o Regulation of gene expression at the level of translation: Inhibit gene expression of a dominant protein. This is done by regulating translation. Bacteria do it using antisense RNA. Antisense RNA will complimentary bind its sequence to a specific mRNA sequence. This forms an RNA double stranded. RNA must be single stranded in order for it to translate. We use antisense DNA because it is easier to manufacture. Antisense DNA makes its way into the nucleus of the cell where it binds to a specific sequence and translation can no longer occur (double stranded → doesn’t work AND the double stranded nucleic acid doesn’t leave the nucleus. Translation usually occurs in the ER)
• o Another therapy is triplet DNA therapy regulation at transcription level: DNA strand that is complimentary to template strand. This is important because in transcription it only reads off the template strand DNA. This prevents DNA polymerase from attaching, binding and reading.
• • This process in its early stages – trouble getting DNA into nucleus
• • Can be used for cancer
• • Slide 1 11/12 VIRUSES
• o Ways to tell a virus is alive: growth, heredity, metabolism, protective mechanisms, transport of substances
• o A virus cant do this stuff independently → it can do it once it infects a cell. Virus should be considered as infectious particle.
• • Slide 2 Virus size
• o Virus size are less than .2 um → VERY small
• • Slide 3 virus structure
• o Virion – completed virus particle which has two parts
• • Outer covering – consists of a capsid and an envelope
•  Capsid (made with same protein subunit called capsomer) comes in two different forms: helical and Icosahedron.
• • Helical form - Capsids bind to one another and extend in a condensed helix. It manifests itself in a rod → called a naked virus.
• • Icosahedron – a polyhedron (3-d structure that contains sides that are polygons – a polygon has three straight sides and three angles). Icosahedron is made up of twenty polygons. This formation is called a facet. The facets are made up of 20 capsomers. As a result of this geometric formation there are 12 equally spaced corners. At each corner is 5 capsomers called penton center.
•  Envolope
• • Taken from the cell host. The envolope provides additional protection for the genetic material AND aids in release of genetic material into cell host.
• • Central core – consists of genetic material and enzymes
• o All viruses will have a capsid and genetic material meaning they also must have an outer covering and central core.
• • Slide 4 genetic material of viruses
• o Viruses contain either DNA or RNA (not both)
• o Viruses also use single stranded nucleic acids as their genetic code.
• o Because viruses are very small their genetic material must be concise. Hepatitis B has 4 genes (Human eukaryote has tens of thousands of genes). Those genes in a virus must code for synthesis of the viral capsid and genetic material, produce protein products that will regulate the actions of their cell host, they need to code for genes that will help package the virus (virion).
• • Slide 5 viral multiplication
• o 1st step – absorption
• o viruses attack specific cells. They determine it based on receptors of the cell host. This can help us characterize viruses into these categories:
• • restricted: example hep B → only infects liver cells
• • intermediate: example polio virus → infects intestinal cells and nerve cells
• • broad: example rabies virus → infects a bunch of eukaryotic cells
• • slide 6
• o it needs to release its genetic material into the cell host. This can be done by endocytosis (similar to how an amoeba eats food). Food vacuole is formed. Food vacuole is bombarded with enzymes and breaks down the capsid. As a result genetic material is released into the cell.
• o It can also transfer its DNA by merging. As it merges it will spread open and genetic material is released.
• • Slide 7 synthesis and assembly
• o Double stranded DNA virus can recombine into our genome and creates potential for cancer.
• o RNA polymerase transcribes viral DNA → it then moves to the ER where it is translated → proteins are then brought back in to the cytoplasm.
• • Slide 8 viral release
• o There will either be cell lyses or exocytosis.
• o Cell membrane is critical to life of cell