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Infectious Diseases Notes.docx

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Infectious Diseases Notes Intro: Viruses and bacteria are very different; you cannot treat viruses with antibiotics, they will not work Bacteria are living organisms (can live by themselves) and viruses cannot live by themselves, they need host cells to allow them to grow and divide Antibiotics attack structures that bacteria have Drugs need to be very specific to target the virus and not the host cell How to determine what organism caused what disease? • Koch’s Postulates o B. anthracis caused the disease anthrax in mice o The microorganism must be present in every case of the disease and absent from the healthy host (1)  Correlation o The microorganism must be isolated and grown in pure culture (2) o The same disease must result when the isolated microorganism is placed in a healthy host (3) o The same microorganism must be isolated from the newly diseased host (4) Viruses: • Viruses are infectious agents with a simple structural organization. • They contain only one type of nucleic acid (either DNA or RNA) and they can only reproduce inside a living cell. • All viruses have a nucleocapsid: DNA or RNA (single or double stranded) which is the viruses genetic material, surrounded by a protein coat called a capsid, which protects the genetic material. • Some viruses contain additional structures such as an envelope (membrane surrounding capsid). • Until the 1800s viruses were often confused with bacteria. Charles Chamberland developed a porcelain filter that allowed bacteria to be separated from viruses (showing viruses caused diseases) o Viruses are much smaller than bacteria • Spike proteins surround the virus to either get into the host cell and recognize it or to get out of the cell o Hemagglutinin ▯ bind to a receptor (lock and key) and the virus knows it has the right tissue in order to replicate  Recognizers are taken advantage of by the viruses o Neuraminidase Steps in replication of virus 1. Attachment to host cell 2. Penetration and uncoating a. Direct penetration – genetic material is injected into the host cell b. Fuse with cytoplasm membrane – capsid I released inside the host cell (envelope virus) c. Endocytosis – virus engulfed in vesicle, vesicle transports virus inside host, virus fuses with vesicle membrane, capsid released (enveloped viruses) 3. Replication of virus genetic material and transcription of virus genes a. Influenza – enzyme to replicate b. Different for all c. Some viruses carry own transcription and others use the hosts transcription machinery d. ReplicateALOT (thousands per host cell or more) 4. Synthesis of capsid and other virus structures 5. Virus Release a. Host cell lysis ▯ cell bursts open and release virus b. Budding ▯ Capsid docks next to membrane, then the membrane detaches (sometimes leads to cell death) i. Virus takes spike proteins with it because of the host cell c. Exocytosis ▯ Capsid and vesicle fuse and the virus is released RNA polymerous ▯ duplicated DNA Bacteria: • Bacteria are prokaryotes • Prokaryootic cells lack a membrane-bound nucleus and they are less complex morphologically than eukaryotes • Reproduce asexually • Include eubacteria and archaebacteria • Most numerous organisms make up most of the earths biomass (about 90%) • Live in biofilms o Large, highly organized communities of microbial cells attached to a solid surface (liquid) o Major cause of persistent bacterial infections in humans o Clog industrial machinery, medical equipment, and contaminate water supply o The cells that make up a biofilm are embedded in a polysaccharide cellular matrix o Once they get started, they are extremely difficult to kill  Easiest way to stop them is to not get one in the first place  Resistant to toxic chemicals (biofilm protects them rom chemicals)  Cells on inner layers are protected by the ones on the outer-layer  Persister cells: not resistant to antibiotics, and since they are dormant, it is harder for bacteria to kill because they are more resistant (dormant while antibacterial are working and then move when the antibiotic stops and regrows again)  Protective barrier, acquire resistance, tolerant  Found everywhere! • Sponges, bath tubs, sinks, towels, drains, vases, aquariums, pools, hot tubs, water systems, cutting board, toilets, oral cavity, vegetables, medical devices, contact lenses Persistent infections caused by biofilms • Pseudomonas aeruginosa – known to cause pneumonia, especially in cystic fibrosis patients an opportunistic pathogen o Lung infections • Vibrio cholera – causes illness known as cholera, an infection of small intestine • Staphylococcus aureus – staphylococcus infections on the skin *Antibiotic research going down, problem that isn’t getting addressed Bacterial cell structure: • Nucleoid • Ribosome • Inclusion bodies • Capsule • Cell wall • Plasma membrane • Outer membrane • Flagellum Bacterial Cell Shapes: o Spherical shaped or cocci o Rod shaped or vacillus o Spiral or helical shaped: spirilla if rigid and spirchetes if flexible Membranes • Membranes contain lipids and proteins • Lipids are structurally asymmetric with polar and non polar ends and they are arranged in a bilayer • Bacterial membrane contains two types of proteins, integral membrane proteins and peripheral membrane proteins • Integral membrane proteins are tightly associated with the membrane and can only be disassociated with detergents (SOAP) o Embedded • Peripheral membrane proteins are loosely connected to the cell membrane and can be dissociated using salts o Attached to the integral membrane • Many bacterial membranes also contain sterol-like (cholesterols) molecules The cell wall • Relatively rigid structure that lies just outside the plasma membrane. It gives bacteria the shape and helps protect them from osmotic shock and lysis. • Composed of a polymer called peptidoglycan. Outer Membrane • The outer membrane of a Gram o Lipid A(Gram -) contains two glucasamine sugar derivatives, which have three fatty acids o O Side Chain – extends out from the surface of the outer membrane. It is a chain of sugars, and many of the sugars are unusual. O-side chains are recognized by our immune system Ribosomes – site of protein synthesis in the bacterial cell. Complex objects made out of both protein and RNA (called rRNA). The proteins and rRNA are different from those used by eukaryotes (good targets for antibiotics) Inclusion bodies – granules of organic or inorganic matter; used for storing Types of Bacterial Mobility • Swimming flagella are used to move in a liquid environment (good targets for our immune system not antibiotics) • Gliding-pili are often used for movement on solid surfaces, flagella are also used (like biofilms) • Why do they move? To find food such as human tissue, to leave unfavorable environments, and use chemotaxis-movement up a chemical gradient of attractants or down a chemical gradient of repellants What causes it, how do you get it, prognosis, can it be transferred, where does it come from, overview Lyme disease: • Most common in the tick borne disease in Northern Hemisphere • On a few species of hard bodied ticks carry the bacterium that cause the disease • Infected tick bites them and the bacterium enters the body • First sign of infection is usually a circular rash called erythema migrans or EM o Rash expands with redness in center and expands up to 12 inches o Other symptoms fever, headache, fatigue, loss of muscle tone, bells palsy, neck stiffness due to meningitis, shooting pains, interfere with sleep, dizziness, heart palpitations, pains in joints (many will resolve without treatment) • The rash occurs in 70-80% of infected persons and beings at the site of a tick bite between 2-30 days • If untreated, it can spread throughout the body • Could develop arthritis or neurological complaints • Can be cured with antibiotics (doxycycline and amoxicillin) especially in early phases • Some patients can have symptoms for months or years after the treatment (autoimmune reaction) • Steps to prevent are insect repellent and removing ticks promptly Mycobacterium Tuberculosis: • MTB as the causative agent of the lung disease tuberculosis • Mtb is transmitted the respiratory route; it is very contagious, you can contract it from talking to an infected person • Mtb stains as if it was a typical Gram positive bacterium (not one though) • At one time it was the most important disease of humans (1/7 of all deaths) • 11,000 new cases of TB each year and about 750 deaths annually mostly occur in people withAIDS • 1/3 of the population have been infected • Worldwide, accounts for 1.6 million deaths per year (11% of infectious disease deaths) • Very complex; determined by the virulence of the strain and the resistance of the host immune system • Cell-mediated immunity plays a critical role in the prevention of an active disease after infection • In many cases, Mtb that has entered the lungs will be walled-off by aggregates of macrophages (granuloma) • Often, Mtb will be localized in the granuloma throughout the lifetime of the host and the host will remain asymptomatic • Latent Mtb ▯ can be activated by aging, malnutrition, stress and hormonal changes (acute pulmonary infections may then occur leading to extensive destruction of lung tissue) • Exposure makes a person hypersensitive to the bacterium; a diagnostic test (tuberculin test) can be used to measure the hypersensitivity by putting a protein fraction beneath the skin and there is also a blood test • 80% of population in many Asian andAfrican countries test positive in the tuberculin test whereas 5-10% of the US population tests positive • INH is the most common drug also rifampin, pyrazinamide, and ethambutol o Not very expensive o Take many if active and less if latent o Need to take for about 6-9 months because it takes awhile to die Food Poisoning: • CDC estimates more than 76 millionAmericans get sick, over 300,00 are hospitalized and 5,000 people die each year • Food born illnesses going down • Food, even cooked, provides a great environment for diseases causing bacteria and deposit their toxins • Spoiled/contaminated food usually has an unpleasant appearance, scent or taste (bacteria present in large numbers) • Sometimes, it is difficult to detect that food is contaminated. This often occurs when the bacteria are present in small numbers. • Contaminating microbes enter food from a variety of sources o Air born organisms can fall onto the food at any point o Crops carry soil born bacterial species o Shellfish concentrate organism in their filtering apparatus o Rodents and insects carry microbes on their feet and body parts, which they deposit while walking through our food o Human handling of food is a major source of contamination o Bacterial species from an animals intestine can contaminate meat when the meat is not processed properly at the butcher or meat processing facility  Hamburger meat especially o Raw vegetables such as those typically found at a salad bar can also become contaminated if not handled and washed properly before serving • Major players: o Salmonella  CDC estimates 1 million people are infected with salmonella, amounting to $365 million in direct medical costs annually  Transmitted by undercooked foods such as eggs, poultry, dairy products and seafood  Species cause a moderate illness with nausea, vomiting, crampy diarrhea, and headache which comes back a few weeks later as arthritis  In people with impaired immune system such as people HIV/AIDS, salmonella can cause a life threatening illness o Campylobacter  Causes mild illness with fever, watery diarrhea, headache and muscle aches.  Most commonly identified food-borne illness in the world  Transmitted by raw poultry, raw milk and water contaminated b animal feces o Staphylococcus aureus  Causes moderate to severe illness with rapid onset of nausea, severe vomiting, dizziness and abdominal cramping  Bacteria produce a toxin in foods such as cream-filled cakes and pies, salads and dairy products o Caullus cereus  Causes mild illness with rapid onset of vomiting with our without diarrhea and abdominal cramping  Associated with rice (fried rice) and other starchy foods such as pasta or potatoes  Potential terrorist weapon o E.Coli  Causes moderate to severe illness that beings as watery diarrhea which turns to bloody diarrhea  Many different types – worst can cause kidney failure and death (3-5%)  Transmitted by eating raw or undercooked hamburger, unpasteurized milk or juices, and contaminated well water  Outbreaks of food poisoning occurs from ingestion of contaminated produce o Listeria  Moderate to severe illness with nausea an vomiting can progress to meningitis  Transmitted on many types of uncooked foods such as fruits and vegetables  In 2011 there was an outbreak of cantaloupe, 25 people died and 123 people were affected in 26 states o Cholerae  Causes the disease cholera – moderate to mild illness with crampy diarrhea, headache, nausea, vomiting and fever with chills  In can be transmitted by infected undercooked or raw seafood  Water supply because of poor sanitation (drinking water or food washed with water) o Vibrio parahaemolyticus  Causes moderate to severe abdominal cramping, nausea vomiting and fever o Helicobacter pylori  Gram-negative pathogen associated with gastritis (chronic inflammation of the stomach, particularly the mucosal layer) ulcers and gastric cancers • Inflammation, tissue destruction and ulceration • Link to cancer  Person to person contact, and ingestion of contaminated food or water are the probably transmission methods  Ulcer biopsy  Products such as the toxin VacA may contribute to the destruction of stomach tissue and ulceration  14 day antibiotic (long-term cure) Sexually Transmitted Diseases Gonorrhea: • Gram-negative bacterium • Person to person • Symptoms different from male to females o Mild vaginitis in females (infection often goes untreated)  If untreated it can cause PID or chronic inflammation or even sterility o Painful infection in the urethral canal for males  Rarely goes untreated in males  If untreated, could cause damage to heart and joint tissue • Treatment used to be penicillin but not so successful due to resistance so now they use Cephalosporins • Acquired immunity does not exist (bacterium undergoes antigenic switching), contraceptives are commonly used by women and they alter the mucosa of the vagina in ways that favor infection, symptoms in females is so mild it can go untreated and transferred Treponema: • Spirochete that causes the sexually transmitted disease, syphilis • Often transmitted with gonorrhea and more serious if not treated • In the US, the incidence of syphilis is much lower than that of gonorrhea (symptoms are much more apparent) • Does not pass through unbroken skin and initial infection probably takes place through breaks in the epidermal layer • Males ▯ penis and females ▯ vagina or cervix • 10% through oral • Stage 1: disease always begin with a localized infection known as primary syphilis (site of entry form a characteristic lesion) Lesions can be seen. • Stage 2: some cells from the lesion spread to various parts of the body such as the mucus membranes, eyes, joints, nervous systems, bones. Infected personally typically becomes hypersensitive resulting in generalized skin rash; ¼ patients appear to be able to rid after stage 2 another ¼ are capable of remaining asymptomatic and the rest go to stage 3 • Stage 3: relatively mild to sever infection; could be fatal if involved in cardio vascular or nervous system; low numbers of bacteria present during tertiary syphilis and most of the symptoms probably result from inflammation from delayed hypersensitivity • Most do not go past first stage Chlamydia: • As many as 3 million new cases of this each year, making this the most common sexually transmitted bacterial disease • Infections are not apparent often • Infections can sometimes lead to serious acute complications such as testicular swelling, prostate inflammation in men and inflammation of the cervix, PID, and fallopian tube damage • Untreated infections can lead to infertility • Specific tests to detect chlamydia • Antibiotics: azithromycin or doxycycline • Infection are often observed as secondary infections following gonorrhea Pertussis : • Gram-negative causes the serious childhood respiratory disease called whopping cough • Acute, highly infectious respiratory disease (children under 5 years old) • Attaches to upper respiratory tract • Characterized by recurrent, violent coughing that can last up to 6 weeks o Sometimes stop breathing o Seems like choking • Fever and sore throat • 50 million cases a year worldwide and 350,00 deaths • 5,000 to 7,0000 cases are reports in the US each year (less but growing) • Thought of as a childhood disease but actually affects people of all ages o People sometimes do not realize that they have it o People are not vaccinated regularly enough, children are vaccinated but people older need a booster o Problematic for infants (complications sometimes causing death) • Treated with antibiotics such as azithromycin, erythromycin, and clarithromycin • Neither vaccination nor natural infection guarantees lifelong protection and immunity decreases so people need to keep getting vaccinated Cornybacterium: • Gram negative • Severe respiratory disease that usually affects children • Spread form person to person • Enters the body via the respiratory rough with cells lodging in in the throat and tonsils • Strong toxin ▯ inhibit protein synthesis in eukaryotic cells, killing the cell • If the disease goes untreated then the toxin can cause systematic damage to the heart, kidneys, liver and other organs • With vaccines it is less common now • 50,000 cases per year, in places were there is no immunization program • Antibiotics (penicillin and erythromycin) and the diphtheria antitoxin which inactivates the toxin • Early treatment is essential Bacterial Meningitis: • Inflammation of the membranes that line the central nervous system • Gram negative bacterium that causes bacterial meningitis (viral also) • Needs to be treated quickly as it could cause death • Epidemics ▯ and usually closed populations • 30% of population carry it in their upper respiratory tract but remain symptomatic • when epidemic, prevalence of carriers rises to 80% • acute infection can be transferred in the air • in some cases it can get into the blood stream and cause septicemia • Sudden onset of vomiting, headache, neck pain and stiff neck and can progress to coma and death in a matter of hours (death in 3% of cases) • Only 2,000 cases per year in the US • No long term vaccines available to treat • In epidemic, purified polysaccharides from some of the most prevalent pathogenic strain are used to immunize those who are in close contact with infect (quarantine) • Penicillin G is the drug to treat the infection but there are some resistant strains that have appeared recently o Chlorphenicol and Cephalospoinrs are used as back up • Other bacteria can cause it: staphylococcus and streptococcus and haempohilus influenza • H.influenze primarily infects younger children (required for US children in schools) Strep: • Strep and pneumonia are important respiratory pathogens • Pygones transmitted via aerosols • Although a number of endegoneous pyognese are typically very low, if host defenses are weakened or a new, highly virulent strain is introduced accutr infections are possible • Pyogenses causes strep throat • Produce a toxin that lyces red blood cell • 50% of causes of sever soar throat are due to pyogenese (mostly viral in origin) • Rapid and complete treatment of strep throat is important because it occasionally can lead to more severe symptoms and more serious strep syndromes: fevers and toxic shock syndrome • Certain s.pyogenses carry a lysogenic phage that contains the gene for exotoxinA which are responsible for most of the symptoms of strep, toxic shock syndrome, and scarlet fever. • Exotoxin Ais a super antigen that induces a massive immune response in the infected tissues • Strep toxic shock syndrome is the term given to the systemic spread of exotoxinA (life threatening) • Many of the symptoms of scarlet fever are similar to strep throat but scarlet fever includes a red “scarlet” tongue • Untreated pyogense infections may lead to severe diseases • Rheumatic fever is on of these disease o Permanent damage o Exposure to new strep infections o Quick treatment will help prevent complications • Some pyogenes strains contain cell surface antigens that are similar to certain to human cell surface antigens • Pyogenese can cause inner ear infections, mammary glands, superficial layers of the skin (impetigo) • On rare occasions, can cause flesh eating bacteria Staphylococcus: • Common pathogens in humans, occasionally life-threatening disease • Commonly infect the skin and wounds • Normal flora on humans most infections form these normal flora • To most important species: s. epidermis, s. aureus • Acne, boils, carditis, impetigo, meningitis, and arthritis • The most common habitat of s.aureus are the upper respiratory tract, especially the nose and throat and surface of the skin • Resident s.aureus strains do not usually cause diseases • Serous infections often occur when the resistance of the host is low because of hormonal changes and low immune system • Strains of s.aurues that most frequently cause disease produce a number of extracellular enzymes or toxins • Strains produce a variety of additional virulence factors including proteolytic enzymes, lipases, RNAses, DNAses • Certain strains have been linked to toxic shock syndrome (first recognized with tampons and biofilms on tampons, now surgery also); toxin is a super antigen • Another entertoxinA, another superanitgen, causes food poisoning o Strong immune response in the intestines • Extensive use of antiobtics has resulted in the selection of resistant s.epidermis and s.aureus strains. Disease producing isolates must be checked individually for antibiotic resistance. o Staph major issue in hospitals Virsues and Cancer: • Viruses linked to cancer carry cancer causing genes or oncogenes • Also vurises that cause persistent damage to host cells may increase chances of cancer • Two types of genes have been implicated o Proto-oncogense promote growth o Tumor suppressor genes suppress growth • Epstein-Barr virus – member of the herpes virus family (double strended DNA vrisus) and one of the most common o as many as 95% of adults have been infected by the time they reach theages of the 35-40 o kissing disease o initial infections can casue mononucleosis (35-50% of the time) o 1-4 weeks of symptoms (fever, sore throat, extreme fatigue, swollen liver and glands); rarely fatal o many healthy people can carry and spread the EBV and spread it throughout their lives even if they are asymptomatic o there is no specific treatment for infectious mononucleosis other than treating the symptoms (no antiviral drugs or vaccines available) o Burkett’s lymphoma ▯ EBV infected lymphocytes, most common childhood malignancy in equatorialAfrica o Nasopharyngeal carcinoma▯ rare in almost all populations but it is one of the most common cancers in southern China; related to EBV infection o Hodgkins ▯ EBV genetic material reported in up to 50% of cases, certain geographic areas/populations • Cancer HPV o Double stranded DNA virus that infects the skin and mucous membranes o More than 100 known types o Contagious o Some cause warts and other cause cancer o More than 40 HPV types that can infect the genital areas of males and females and also the mouth/throat o HPV is the most common STD in the US o At least 50% of sexually active people have genital HPV at some point in their lives o Aperson could have HPV for years and passed it even if they don’t realize they have it (pregnant women can give it to baby during deliver o Could become respiratory RPP o In 90% the body’s immune system clears HPV in two years o If it doesn’t, an infected person can develop genital warts and they can sometimes be in the throat o HPV that cause genital warts are not the same as the ones that cause cancer o Main cause of cervical cancer (almost exclusively) o No symptoms until it is quite advanced so getting screened is important o Vaccines can protect makes and females against it • Cervical Cancer o Herpes simplex 2 virus which is a double stranded DNA virus that causes genital sores • Liver Cancer o Hep B – double stranded DNA virus can be integrated into the genome of liver cells, disrupting their normal function. Can cause liver cirrhosis and is also though to be one of the leading causes of primary cancer o Hep C – single stranded RNA virus that causes liver cirrhosis and damages liver cells that leads to their replacement which can cause malignancies and mutations o HTLV is a retrovirus can cause adult T-Cell leukemia • HSV o Most likely mode of HSV transmission is through direct contact with infected area/person o Aperson can be infected with one or both herpes viruses o HSV 1 infections occurred in the mouth and HSV 2 infections occurred in the genital area (now either can infect either site) o DNA viruses o Effect epithelial cells, more people do not get symptoms o Ulcers, blisters and sores heal within a week usually o During the infection some virus particles move to the sensory nerve endings in the infected part of the skin o The virus is transported through the nerve fibers to the nerve ganglia and persists there as circular DNA (dormant or latent) ▯ latency last a lifetime o Certain triggers are associated with reoccurring infection (stress, UV light, fatigue) ▯ could move from ganglia back down to fibers of infected area o No cure for herpes, cold sores are treated topically with anti0viral creams, genital herpes is treated with oral anti-viral medication, maintenance treatments may be taken for those with frequent or sever outbreaks, a vaccination may be available in the future and wont be able to treat those who are already infected • Chickenpox o Highly contagious skin disease in mostly children ages 2-7 o Herpes virus family o Vaccine available since 1995 o Rarely fatal o Spread through the air o 10-21 days after contact o Fever, rash, blister life, lifelong immunity (never get it again) o Can lead to shingles, varscella zoster remains in nerve cells/tissue and can be reactivated o Possible reasons for getting shingles: stress, fatigue, a weakened immune system o the first symptoms are extreme sensitivity or pain in a broad band on one side of the body o Later, blisters develop in the same distribution of the pain o Typically, the blisters scab over and disappear within 2-3 weeks; scarring may result o Aperson with shingles can transmit the virus to another person with direct contact to the blisters; they will develop chickenpox if they haven’t had it before • Hepatitus o Caused by different viruses (HepA, B, and C) o Effect liver cells o Hep A  Less severe of all of them  Single stranded RNA virus with no envelope, picornovarius family  Transmitted form fecal-oral contaminated food, water of from close contact with someone who is already infected  Flue like symptoms, severe stomach pains, jaundice  Most are mild cases and don’t require treatment and recover completely with no liver damage, 1 in 5 are hospitalized, often too sick to work, . 3-.6% of people infected will die  Vaccine o Hep B  Amember of the hepadnavirus  Causes liver cell (hepatocytes) damage  Unrelated virus of hepatitis (no cross-immunity)  Double stranded DNA virus  Transmission results from exposure to infectious blood (also semen or other bodily fluids)  Blood transfusions  Acute or chronic • Acute: short-term illness that occurs within the first 6 months after someone is exposed and it can lead to chronic • Chronic: long-term illness remains in body can result in long term liver problems and maybe death o 90% of infected infants will develop chronic o 25-50% of children between 1-5 years will develop chronic o 6-10% will be chronic over the age of 6 o 8000,000 in US have chronic infection o 350 million people globally, 620,000 deaths each year  Vaccines for Hep B but none for Hep C  You can get another if you’ve had one and you are not vaccinated if you have just one o Hep C  Single stranded RNA virus with an envelope  Transmission: regular contact with blood, shared needles, blood transfusions before 1992, unprotected sex (more partners also), received a tattoo or acupuncture with contaminated instruments  1.5% of US populated infected with Hep C virus  130-170 million people worldwide are infected  Hep C has an acute and chronic form (75-85% of infected people develop chronic symptoms)  Most people who are infected with the virus develop chronic liver disease (1-%% develop liver cirrhosis or cancer)  Approx. 15-25% who get it will clear the virus from their bodies  Most people do not have symptoms, 10% develop jaundice but get better, in many cases no symptoms until liver cirrhosis develops  Possible symptoms: abdominal pain, bleeding from stomach, jaundice  No vaccine but there are anti0viral drugs that can be taken, 24-48 week treatment and side effects are dramatic. Retroviruses: • RNA viruses o Enveloped viruses o Genome is single stranded RNA (mRNA) o The virus particle (virion) caries single stranded RNA and the enzyme reverse transcriptase o The double stranded DNA is incorporated in the host cell genome by the enzyme integrase o The double stranded DNA from the virus replicates along with the host cell NDA o Some of the single stranded mRNA genome of the retroviruses is used to make viral proteins o HIV (Human Immunodeficiency Virus)  AIDS first described in 1981  Originated in centralAfrican before the 1950s  Simian Immunodeficiency Virus is similar to HIV,African primates  Spread fromAfrica to the Caribbean and then to the US  Acquired by direct contact with blood (fluids)  Maybe be acquired through breast milk  Spike pretein gp120 binds the CD4 receptor molecule on T helper cells (activate other cells)  Internalization and uncoating of the virus within the host cells  Reverse transcriptase makes DNA copy of mRNA genome  Viral DNA inserts into host cell genome  Activation of provirus results in rapid production of virus (10 to the seventh particles a day) ▯ might take awhile  Budding, rip off a piece of the host cell membrane and if forms the cell envelope of the virus • Lycing could occur from budding and damage  Cytopathic effects (CPE) • The virus is released slowly so host cells do not lyse o Inclusion o Giant fused o Cell detachment and rounding  CDC estimates 1.3 million people in the US are living with HIV infection 1/5 people are not aware that they have it.  Annual number of new HIV infections has remained fairly constant, 50,000 new cases a year  HIV is spread most often through unprotected sex. Virus can enter the body through the lining of the vagina, vulva, penis, rectum or mouth during sec.  Shared needles and syringes, sexual contact without condom, sexual contact without knowing the other persons status, ¼ infected mothers pass to babies. • Alot of hysteria in the 80s about transferring  Many epopel will not have any symptoms when they first become infected, some people have flu-like illness within a month ror two after exposure  More persistant or severe symptoms may appear within a few months or they may take as long as 10 years  As the immune system becomes more debilitated, a variety of complications start to take over  For many people, the first signs of the infection are large lymph nodes, or swollen glands that may be enlarged for more than 3 months  Lack of energy, weight loss, frequent yeast infections, skin rashes or flaky skin, frequent fevers, memory loss  Prone to opportunistic infections and to developing various cancers  TYPES • Candi
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