Viruses: A Detailed Overview PDF

Filterable virus Chamberland- 1800s- took tobacco leaf infected with tobacco mosaic virus- made a paste out of it- filtered it with small enough pores to filter out bacteria- rubbed filtered paste onto uninfected leaf-caused disease on that leaf too PROVED THAT VIRUSES EXIST-agent smaller than bact...

Filterable virus Chamberland- 1800s- took tobacco leaf infected with tobacco mosaic virus- made a paste out of it- filtered it with small enough pores to filter out bacteria- rubbed filtered paste onto uninfected leaf-caused disease on that leaf too PROVED THAT VIRUSES EXIST-agent smaller than bacteria Infectious fluids were passed through filters designed to trap bacteria The cell-free filtered fluid remained infectious This proved that an agent smaller than bacteria was the cause of the disease Causes common cold-rhinovirus emerging viruses A virus that has appeared suddenly or has recently come to the attention of medical scientists. Covid, avian influenza, H5N1 Virus A bag of DNA or RNA(nucleic acid-either RNA or DNA, surrounded by a protein capsid) Nonliving infectious agent Obligate parasite that needs a host(host-specific!) Generally too small to filter out Obligate parasite unable to grow outside of a living host Antibiotics do not kill _____. Viruses Sometimes, antibiotics are given for viral infections to prevent ____________. Secondary bacterial infection Ex. Antibiotics to prevent bacterial pneumonia in a person with whooping couch(which is a virus) Viruses- Random facts to know Measles- rash, respiratory infection Mumps- lymph nodes, can cause sterility in MALES Polio- spreads via fecal contamination- water- March of Dimes women raised money for polio research in the 1930s/40s/50s Rabies-has vaccine for dogs Shingles- a herpes virus, chickenpox Wart- burn or freeze to trigger immune system to attack, liquid nitrogen, HPV=wart, can turn on cancers, especially cervical and penile Colorful tulips- A virus that humans infect tulips with Smallpox- Eliminates worldwide in the 1970s via vaccine Smallpox vaccine causes the development of a pustule full of live virus, which can be contagious when it ruptures Canker sores/cold sores- herpes 1 virus Influenza- dangerous since it causes secondary infections, mutates very fast Ex. H5N1- bird to dairy cow to human Mass termination of birds for avian influenza Ex. canine influenza- show dogs are often vaccinated Envelope virus Virus with a phospholipid envelope Ex. Flu Non-envelope (naked) virus No extra layer Ex.Herpes electron microscope 1945 Need it to see viruses First human viral disease diagnosis from an animal Sir Walter Reed-1901- Transmission of yellow fever from mosquitos to humans in South America Humans cut down trees, the monkeys that mosquitos fed on left, mosquitos fed on humans instead, infected them with yellow fever Controls for viruses Vaccination Chemical control Ex- Polio has a vaccine We add chlorine to pool water to prevent it Agent that kills viruses virucide Bacteriophage A virus that infects bacteria, complex virus Types of nucleic acids in viruses ssRNA(mRNA) ssDNA dsDNA dsRNA Example of a ssDNA virus Parvovirus Puppies-fecal material Example of a ssRNA virus influenza a ssRNA virus with two ssRNA strands HIV (unusual!)-attacks T Helper cell-no immune system now! Enveloped virus Reverse transcriptase- retrovirus Transcribes RNA to DNA HIV enters cell, capsid proteins removed in the cytoplasm, RNA released, reverse transcriptase to DNA, DNA to nucleus, transcribes to mRNA for genome and released back to cytoplasm, capsid assembled around genomes, new HIVs bud from host cell! Glycoprotein spikes On the capsid or the envolope Used by mumps virus or HIV to attach to host receptors protein encoded by NA, integrated into the viral envelope Ex. hemagglutinin neuraminidase- attach to lungs Common in making flu cavvine capsomer A subunit of the virus capsid shaped as a triangle or disc. Bacteriophage anatomy Phage head Tail Tail fibers(used to attatch/inject) lytic cycle cycle of viral infection; results in replication of virus and cell destruction LYSES CELL lysogenic cycle a viral reproductive cycle in which the viral DNA is added to the host cell's DNA and is copied along with the host cell's DNA Viral Replication 1. ADSORPTION(attatchment of virus to host cell-glycoprotien spikes of virus bind to the receptors of the host cell) 2. PENETRATION(host cell can bring it in by vacuole/vesicle or virus can enter by itself) and UNCOATING(envolope/capsid is dissolved and the nucleic acid of the virus is released into cell cytoplasm) 3. SYNTHESIS/REPLICATION(nucleic acids translated into building blocks for new viruses, host cell machinery used) 4. MATURATION/ASSEMBLY (mature virus particles assembled from parts) 5. RELEASE (nonenveloped/complex viruses released when cell lyses, enveloped viruses released by budding through a membrane-ex. ER/cytoplasmic/etc- thus gaining their envelope) Retrovirus An RNA virus that reproduces by transcribing its RNA into DNA and then inserting the DNA into a cellular chromosome; an important class of cancer-causing viruses. DNA virus DNA is replicated and form new viral DNA => transcribed to produce viral proteins (DNA + viral proteins assemble to form new viruses). The protein coat disintegrates in the cytoplasm, DNA enters nucleus where replication and transcription occurs, mRNA goes to cytoplasm for translation of capsid proteins, return to nucleus for virion assembly RNA Virus A virus in which the genetic information is stored in the form of RNA (as opposed to DNA). Reproduction occurs in the cytoplasm Ex. Picornavirus Complex virus A virus with a complicated structure, such as a bacteriophage. virion complete virus particle Antiviral drugs: Inhibition of virus entry- EXAMPLES Amantidine: Blocks HIV by preventing it from binding to cell receptors Tamiflu: Blocks INFLUENZA by interfering with virus's fusion to cell membrane, stops neuraminidase. Take within 24 hours! Antiviral drugs: Inhibition of nucleic acid synthesis- EXAMPLES Acyclovir: inactivates DNA polymerase, stopping DNA replication in HERPES VIRUSES AZT/Zidovudine: Stops reverse transcriptase in HIV, blocking DNA production Nevirapine: Attaches/blocks HIV rt binding site Antiviral drugs: Inhibition of Viral Assembly/Release- EXAMPLE Saquinavir: Inserts into HIV protease, resulting in inactive viruses protease enzyme that breaks down proteins Vaccination sheets Tells you what you need to know, signed by parents/guardians if minor, nurses have vaccination sheets for many vaccines(Antibodies!) Hep, tetanus, diptheria, etc 6 Requirements for Effective Vaccines 1. Low level adverse side effects, no serious harm/toxicity 2. Protect against exposure to wild, natural, and artificial forms of pathogen 3. Stimulates antibody(B-cell) and cytotoxic(T-cell) response 4. Long term, lasting effect(memory!) 5. Not too many boosters or doses 6. Inexpensive, easy to administer, long shelf life Tdap vaccine/DTP vaccine tetanus, pertussis, and diptheria A toxoid vaccine Why vaccinate? To protect individuals To establish herd immunity - Protection of the whole population Prevention of epidemics - Protection of non-immunized individual How do vaccines work? - pathogen stimulaties wbc into making antigens - dead or inactive pathogen enter body via injection - antibodies stick to antigens and clump them together - memory cells = immunity Stimulate immunity with exposure to the pathogen Innate immunity first line of defense (chemical/physical/cellular barriers) Adaptive immunity the ability to recognize and remember specific antigens and mount an attack on them second line of defense aka acquired immunity Humoral immunity B cells produce antibodies after exposure to specific antigens; type of adaptive immunity cell-mediated immunity type of immunity produced by T cells that attack infected or abnormal body cells; type of adaptive immunity T cytotoxic cell the only T Cells that can DIRECTLY attack and kill diseased cells- including cancer cells T-Helper cell contacts the displayed antigen fragment and releases cytokines that activate B cells T-Suppressor cell Suppresses or stops the reaction of T & B cells or immune reaction Natural Killer Cell A type of white blood cell that can kill tumor cells and virus-infected cells as part of innate immunity, WITHOUT the stimulation of antigens Natural immunity acquired as part of normal life experiences artificial immunity protection from infection obtained through medical procedures Active natural immunity antibodies developed in response to an infection/being sick Active artificial immunity vaccination. Deliberate exposure to an antigen (vaccine) Passive natural immunity IgG transferred from mother to fetus: Across placenta Through breast milk Protection of infant for the first few months of life or until weaned Passive artificial immunity injection of antibodies (immune globulin) short term protection Vaccines with dead/inactive material are made by... Killing the cell/inactivating the virus bye heat or chemicals to denature the proteins and stop attachment but keep cell recognition Pathogens CANNOT multiply Attenuated vaccines are made with... Weakened living pathogens(with reduced virulence) Pathogens can multiply but NOT enough to sicken The only attenuated vaccine issue Polio and babies Cutter vaccine 1955 The influenza vaccine is made of________. glycoprotein spikes from multiple strains of flu viruses (microbe parts vaccine) Acellular vaccine A vaccine preparation that contains parts of BACTERIA to elicit immune response as opposed to the whole cell Type of microbe parts vaccine Examples of Acellular vaccines Tetanus- uses toxin Whooping cough Campylobacter/salmonella- Flagella vaccine Subunit vaccine Vaccine containing only specific antigenic proteins of the infectious VIRUS Microbe parts vaccine Parts of the microbe(antigens, virus or bacteria) are used to stimulate immunity but NO pathogens are present Recombinant vaccine Plasmid vaccine, uses gene for the antigen from the pathogen to stimulate immunity, but no pathogen is present Ex. 7 in 1 animal vaccines Whole cell vaccine- Vaccines containing killed whole bacteria- EXAMPLES Cholera- for travelers, short term effectiveness Whole cell vaccine- Vaccines containing attenuated bacteria- EXAMPLES Tuberculosis- for high risk occupations, protection varies Typhoid- for travelers, low effectiveness Acellular vaccines- Vaccines containing capsular polysaccharides or proteins- EXAMPLES Anthrax- for military protection, occupationally exposed Meningitis- infants and children, with DTaP Pneumococcal pneumonia- high risk people, moderate protection Pertussis(whooping cough)- newborns and children, recombinant protein Ags Acellular vaccines- Vaccines containing toxoids- EXAMPLES Diptheria- routine childhood vaccine, high effectiveness Tetanus- routine childhood vaccine, high effectiveness Pertussis- routine childhood vaccine, high effectiveness Botulism- Exposed laboratory personal Whole cell vaccine- Vaccines containing inactive whole viruses- EXAMPLES Rabies- Exposed/bitten people Influenza- High risk populations, requires constant updating for new strains, not durable immunity Hepatitis A- Travelers and institutionalized peoples Whole cell vaccine- Vaccines containing attenuated viruses EXAMPLES Measles Mumps Rubella Chickenpox(Varicella) Routine childhood vaccines, effective! MMRV Vaccine measles, mumps, rubella, varicella Subunit viral vaccines EXAMPLES Hep B- At birth, healthcare workers/at risk people Influenza Recombinant vaccines EXAMPLES Hepatitis B- At birth, healthcare workers/at risk people(used more than subunit!) Pertussis- Newborns/children HPV-Human Papilloma Virus- 2006- routing childhood/adolescent vaccine How can we diagnose viruses? 1. Signs and Symptoms 2. Cytopathic effects: Tissue culture examination to see evidence of viral cell infection(Speed of infection- virus identification-Polio destroys in 20-30min!) 3. Eggs- Injecting a virus/culture cell into an egg 4. Electron microscope- only way to see a virus, not often used, expensive, used to see parvo in the 80s 5. Gel electrophoresis 6. ELISA- Ag-Ab reaction (put Ag or Ab, in well, add opposing, see if Ag-Ab complex forms by adding an indicator) 7. Genetic analysis- of the viral nucleic acid using probes 8. Serological Testing- evidence of past infection through blood testing Eggs and vaccines: History Used to make vaccines with eggs, some people were allergic We now use human tissues to make rabies vaccines Progression of Disease 1. incubation period 2. prodromal period 3. illness 4. decline 5. convalescence Progression of Disease: Incubation period - No signs/symptoms - Period between initial exposure and first signs/symptoms - Incubation period ex. 21 days-chickenpox 24 hours-flu 6 years- leprosy 24 hours- new e.colis Factors that effect incubation period host age host health host immune system type of organism Progression of Disease: Prodromal Period SHORT characterized by mild symptoms ex. aches, fever, nausea, headache, spots(measles) Progression of Disease: Period of Illness most acute exhibit signs and symptoms for disease ex. strep throat- sore throat chickenpox- pox lesions hepatitis- jaundice High WBCs, high fever, swollen lymph nodes, sore muscles, vomiting Nausea is a symptom in the ________ period, vomiting is a symptom in the __________ period. Nausea: Prodromal Vomiting: Illness Progression of Disease: Period of decline - signs and symptoms decreasing(ex. lowered fever, pox heal, etc.) - takes 24 hours to several days - person is vulnerable to secondary infections (weak!) Progression of Disease: Period of convalesence regain strength, feels better, eating, etc. return to normal can still be subclinical and shedding disease particles ex. cholera Syphillis - number one STD in the US currently - not isolated to genitals, can travel to brain, spinal cord, etc. - bacterial - rash, fever, nervous system deterioration Treat with: - penecillin - condoms Flu: Influenza virus Symptoms: fever, muscle aches, lethargy, headache, sore throat, congestion, cough Incubation: 1-2 days Pathogenesis: Infection of respiratory epithelium, lytic cycle Always mutating slightly, vaccines made of glycoprotein spikes TamiFlu (Amantidine) 1st 24 hours! Chickenpox: Varicella virus Symptoms: Itchy bumps and blisters, fever, can become shingles years later(latent infection) Incubation: 10-21 days Pathogenesis: Enters via upper respiratory infection and then bloodstream to skin Highly infectious- weeping lesions and respiratory secretions Attenuated vaccine Passive immunity- immune globulin Acyclovir Measles: Rubeola Symptoms: Rash, fever, weepy eyes, cough, nasal discharge Incubation: 10-12 days Pathogenesis: respiratory tract, spread to lymph and then whole body Attenuated vaccine, 2 doses, childhood Black Death Plauge Bacteria Symptoms: Sudden high fever, large lymph nodes(buboes), skin hemorrhages, bloody cough Incubation: 1-6 days Pathogenesis: Flea bite, rodents and other wild animals can carry Vaccine not used, not prevelant enough Endemic in native american reservations Mono: Infectious mononucleosis kissing disease Incubation: 1-2 months Symptoms: fatiuge, sore throat, fever, enlarged lymph nodes, swollen liver/spleen-should not exercise! can rupture-, rash, aches Saliva, latent infection(for life asymptomatic) Lockjaw Tetanus Chlostridium Tetani bacteria Symptoms: Restlessness, irratibility, difficulty swallowing, muscle pain and spasm in jaw, or entire body Incubation: 3 days-3 weeks, avg 8 days Endotoxin from bacteria, carried to brain and spinal cord Soil and puncture wound Immunization childhood vaccine, TOXOID VACCINE, which is an acellular vaccine Viral meningitis: Symptoms: Abrupt fever, headache, stiff neck, vomiting, rash, chest pain Incubation: 1-2 weeks enterovirus, 2-4 weeks mumps Mostly enterovirus, mumps is more common in unvaccinated places Fecal-oral Handwashing, avoid pools, mumps vaccine Common Cold: Rhinoviruses Symptoms: Scratchy throat, nasal discharge, headache, cough Incubation: 1-2 days Inhalation of droplets, viruses attach to respiratory epithelium handwashing, not touching face, stay home sick Hantavirus Hantavirus pulmonary syndrome 1986 colorado, moscow, ID Symptoms: Fever, muscle aches, vomiting, diarrhea, cough, shortness of breath, shock Incubation: 8 days to 8 weeks Zoonotic disease- field mice urine Preventing foodborne diseases (8) 1. Clean produce properly 2. Store food properly 3. Inspect meat and seafood 4. Prepare food properly, including adequate cooking 5. General sanitary practices(gloves, hand washing) 6. Restrict sick people(GI pathogens) from food handling 7. Eat food promptly after preperation 8. Use pure water Groups at risk of foodborne illness Pregnant women Older adults Young children Immunocompromised people signs of food poisoning (gastroenteritis) diarrhea, vomiting, bloody diarrhea, fever, dehydration 2-6 hours within consumption Food intoxication result of ingesting a toxin produced by pathogenic microorganisms existing in the food (often from the canning of food, creation of an anaerobic environment, causing the toxin to be produced) Food infection result of ingesting a food containing live, pathogenic microorganisms which then grow in the human intestine causing illness (often from improper cooking of food/cross contamination, bacteria multiply, infect in the intestinal tract) Prions infectious protein particles that do not have a genome Mad cow disease Increase in food industry Brain! Not found yet in body meat Destruction of microbes to prevent food poisoning Canning, pasteurization, cooking, Radiation, Filtration, Preservatives, Heat/cold Federal Trade Commission (FTC) An agency that regulates a variety of business practices and curbs false advertising, misleading pricing, and deceptive packaging and labeling Department of Justice Seizes products when food safety laws are violated, prosecutes Bureau of Alcohol, Tobacco, and Firearms (BATF) regulates advertising of alcoholic beverages National Marine Fisheries Service (NMFS) Responsible for seafood quality and identification, fisheries management and development, habitat conservation and aquaculture production. State and Local Governments Public Health Inspects restraunts, retail food outlets, dairies, grain mills, and other food establishments Embargo illegal food products CDC Centers for Disease Control and Prevention Moniters foodborne illness EPA Environmental Protection Agency regulates pesticides and establishes water quality standards FAO Food and Agriculture Organization Part of the UN Standards for pesticides FDA Food and Drug Administration Part of DOH Ensures safety/wholesomeness of foods processed/sold interstate (except meat poultry and eggs- under USDA) Inspect food plants and imported foods USDA United States Department of Agriculture Meat, poultry, eggs Nutrition research and education WHO World Health Organization pesticides Campylobacter jejuni Raw and undercooked poultry, unpasteurized milk, contaminated water Diarrhea(bloody), abdominal cramping, vomiting, fever, tiredness Clostridium botulinum Botulism Home-canned foods w/ low acididty, improperly canned commercial food, herb oils Vomiting, diarrhea, blurred vision, drooping eyelids, slurred speech, dry mouth, weak muscles Clostridium perfringens gas gangrene Raw/undercooked meat, gravy, dried food Abdominal pain, watery diarrhea, vomiting, nausea Escherichia coli O157:H7 Raw or undercooked meat, raw fruit and veg, unpasteurized milk/juice, contaminated water Nausea, bloody diarrhea, abdominal cramping Listeria monocytogenes Raw/inadequately pasteurized dairy, lunch meats, frankfurters Fever, muscle aches, nausea, diarrhea, premature delivery/miscarrage/stillbirth Salmonella Raw poultry, eggs, beef, fruit, alfalfa sprouts, unpasteurized milk Diarrhea, fever, abdominal cramps, severe headache Shigella raw/undercooked food, FLIES Fever, tiredness, watery/bloody diarrhea, abdominal pain Staphylococcus aureus Improperly refrigerated meats, potato and egg salads, cream pastries Sudden nausea, vomiting, abdominal cramps Vibrio cholerae Cholera Contaminated water, undercooked foods FLOODS Watery diarrhea, vomiting Hepatitis A Mollusks(oysters, clams, mussels, scallops, cockes) SODA Jaundice, fatigue, abdominal pain, loss of appetite, nausea, diarrhea, fever Norovirus Raw/undercooked shellfish, contaminated water CRUISE SHIP VIRUS Nausea, vomiting, diarrhea, abdominal pain, headache, fever Trichonella Worm Raw/undercooked pork or meats of carnivorous animals BEAR MEAT Acute nausea, diarrhea, vomiting, fatigue, fever, abdominal pain Giardia intestinalis Beaver Fever Contaminated water, uncooked food, hikers Massive diarrhea, flatulence, stomach cramps Aspergillus flavus Mold- alphatoxin Wheat, flour, peanuts, soybeans Liver damage and neurological issues