Viruses and Eukaryotes Flashcards

Question

Human Immunodeficiency Virus (HIV) - Retrovirus

Answer 1

Positive sense diploid (two strands in each virion) RNA enveloped retrovirus that gets converted into a DNA intermediate by an accompanying reverse transcriptase and inserts itself into host chromosomes, allowing it to replicate forever Leads to AIDs (acquired immunodeficiency syndrome) Three major genes it uses are the env, gag, and pol 1) gag = p24, capsule for RNA strands 2) env = glycoprotein 41 (transmembrane protein on the envelope) and 120 (outer glycoprotein that interacts with host receptors), form envelop of the virus 3) pol = reverse transcriptase Transmission: sexual, vertical (born with it), or blood (IV drug use, etc.). Initially infects macrophages and helper T cells. Enter T cells via either CCR5 (early entry) or CXCR4 (late stages) receptors Progression: Prodrome consists of flu or mono-like symptoms with cervical lymphadenopathy, fever. Will then enter latent period (can last up to 10 years) where it replicates in lymph nodes until CD4 count drops to below 200, at which point it becomes AIDS. HIV can also cause B cell lymphoma, specifically Diffuse B Cell Lymphoma Diagnosis: ELISA test for Abs, confirm with Western Blot. Treatment: Combination therapy always better than monotherapy. NRTIs (Nucleotide Reverse Transcriptase Inhibitors, backbone of retroviral treatment, halts elongation after being inserted into chain), most commonly used one is Zidovudine, commonly used in pregnant patients. NNRTIs (NonNucleotide Reverse Transcriptase Inhibitors), don't incorporate into chain but has same end result. Protease inhibitors. CCR5 inhibitor (blocks early entry of the virus), commonly used is Maraviroc Need to do genotyping to figure out correct treatment

Answer 2

Enterobius vermicularis Also known as a Pinworm. At nighttime, female worms will migrate down to the anus and lay their eggs. Transmitted via the fecal-oral route. People tend to routinely reinfect themselves as they'll scratch their anus and redo the infectious life cycle Diagnosis: use scotch tape on your anus to see if eggs are present under microscope Treatment: Pyrantel pamoate, and albendazole (all intestinal nematodes can be treated with albendazole) Ancylostoma duodenale and Necator americanus Hookworms. Larvae penetrate the skin of soles of feet, and once in the blood stream go straight to the lungs so they can ascend the bronchial tree and make their way up to get coughed up, and swallowed, and then back down to the small intestines. Attach to gut wall and suck on blood, etc. Patients developed Iron deficiency anemia. Diagnosis: look for eggs in the stool and high eosinophil (eosinophilia). Treatment: albendazole an pyrantel pamoate Ascaris lumbricoides Transmitted by eggs in food or water. And hatch in small intestines, go through, enter blood stream, and go to the lungs. Once there, they enter the capillaries into the alveoli, ascend the bronchus, and then are swallowed again and end up in the small intestines. Of the helminths that migrate through the lungs, Ascaris is the most likely to produce a lung infection. However, main symptom is intestinal obstruction at the iliocecal valve Diagnosis: eggs in stool, eosinophilia Treatment: albendazole (however, be aware this drug eliminates the mobility of these bugs by inhibiting their microtubules, so this could still cause a obstruction), and pyyrantel pamoate Strongyloides stercoralis Larvae penetrate through the skin of soles of feet. Goes to lungs, climbs bronchial tree, gets swallowed, and enters the GI tract where it matures. Can further infect their host by laying their eggs in the GI tract, where they'll penetrate and follow the same life cycle arc as before. Diagnosis: Because eggs are placed in intestinal wall, will not show up in stool, however the larvae will appear in stool, eosinophilia. Treatment: albendazol, or ivermectin. Trichenella spiralis Found in undercooked meat. Causes fever, vomiting, and periorbital edema. Also causes severe myalgia as the ingested cysts will form cysts in striated muscle fibers. Will also present with eosinophilia. Treatment: albendazole

Answer 3

Member of the Herpes virus family, thus it is a dsDNA virus that is also enveloped. Cause of Kaposi sarcoma. AIDS and an immunosuppressed state are associated with Kaposi sarcoma. Kaposi sarcoma presents with violacious (caused by its high vascularity as Kaposi sarcoma causes proliferation of vasculature via dysregulation of VEGF) lesions on the nose, extremities, and mucous membranes (even on the digestive tract, lesions mst commonly occur on the hard palate) Can also infect B cels, causing Primary Effusion B Cell Lymphoma Transmission: Sexual contact, including salivary exchange. Main risk groups are AIDS/immunocompromised individuals, eldery Russian men who have lesions down their lower extremities, and people in Africa where the virus is endemic (these adults in particular will present with palatal lesions, and can be potentially fatal in children) Important to differentiate from Bartonella hensleae (cat scratch disease) as the lesions can look similar. To differentiate, histologically HHV8 will have a lymphocytic infiltrate while Bartonella will have neutrophilic infiltrate Treatment: Give antiretroviral therapy if they are HIV+ and are undiagnosed, lesions may resolve themselves

Answer 4

Positive sense ssRNA, naked virus. Norovirus belongs to the Calicivirus family, and is the most common infection seen from the family. Produces one long polyprotein that is cleaved into active forms, similar to picornavirus. Replicates in the cytoplasm, like all positive RNA viruses Outbreaks happen where there are high concentration of individuals (such as cruises). Strong association with daycare facilities and schools. Commonly ingested via contiminated shellfish and other handled raw food Norovirus causes gastroenteritis, which leads to diarrheal disease characterized by explosive watery diarrhea

Answer 5

RNA negative virus. Like all RNA negatives, it has it's own RNA polymerase to produce positive sense RNA that then uses host machinery to produce viral protein. All negative RNA viruses with the exception are single stranded. Enveloped virus What is unique about this virus is that, unlike all other RNA viruses, this one replicates in the nucleus, all others replicate in the cytoplasm There are three strains of influenza (A,B,and C) and is one of four segmented viruses (BOAR, bunyavirus, orthomyxo, arenavirus, and reovirus are segmented) and has 8 segments Antigenic drift is when there are point mutations in the neuraminidase (NA) or haemagluttinin (HA) genes in influenza virus genome. Reasons we have outbreaks and need new vaccines yearly for this virus Antigenic shift is when antigenic segments from the virus are mixed and shared between viruses, leading to new surface antigens. Responsible for pandemics. Only possible because the flu virus is segmented HA is a glycoprotein that binds to sialic acid URT cells and red blood cells, causes them to clump together in blood. Has different type (HA1, 2, 3, etc. Determines what cells it can bind to, aka tropism). Also HA antibodies protect us M2 protein: creates proper pH that allows for viral encoating. Inhibited by amantadine/rimantadine, prevents uncoating NA: cleaves sialic acid to release new virions after leaving the cell. Targeted by oseltamivir/anamivir, must be given early Spread via respiratory droplets (December to February for spread, better to give vaccine in October). Two vaccines: live attenuated inhaled via the nose vaccine or killed injectable form. Pneumonia is often a complicating factor (Staph aureus and pneuococcus). Treatment with aspirin can cause lots of issues with viral infection, including Reyes syndrome, encephalitis, fatty liver, and liver disease. Associated with Guillain-Barre syndrome

Answer 6

dsDNA virus, naked. Over 100 different types. Relevant types: HPV1-4, HPV 1-4 Cause of verruca vulgaris, which is simple cutaneous common wart. Typically found on hands and feet, but not found on the genitalia. Transmitted via direct contact HPV 6, 11 (Both viruses cause both diseases) Associated with Laryngeal papillomatosis, which is a recurrent respiratory papillomatosis, a condition where tumors (papillomas) develop in the airway, typically seen in children. Picked up during vaginal birth and not thought to be sexually transmitted. Also causes anogenital warts, more formally referred to as Condyloma acuminata. This is transmitted via sexual contact HPV 16, 18 Known to causes squamous cell carcinomas anogenital cancers (HPV infects squamous cells) (Note, HPV 31 and 33 are also associated with anogenital cancers) HPV Vaccine: against 6, 11, 16, and 18 (doesn't cover 31, 33 yet, but 16 and 18 cause 60% of cervical cancer). Under the name gardasil and is an inactivated subunit vaccine. HPV is the most common STD. Also is capable of disrupting the cell cycle, the virus encodes for proteins E6 and E7 which promote the proteolysis of p53 and Rb (retinoblastoma protein, which is a tumor suppressor) respectively, which lead to upregulation of transition from G1S phase A hallmark of cervical cancer is Post-coital bleeding (following sex) Detection: Pap smear is a screening test for cervical cancer, which looks for cells at the transition of columnar epithelium to squamous cell epithelium cells in the cervix. If there is an HPV infection, squamous cells will be altered and look like Koilocytes (large, dense, wrinkled nuclei and may be binucleated. Looks similar to sunny side up eggs). Immunosuppression and HIV patients are at particular risk for invasive cervical/anal/peniles cancers

Answer 7

Systemic fungus localized to South America. Dimorphic like all systemic fungi. Transmitted via respiratory droplets Structure of the yeast form in the lungs takes on that of a "Captain's Wheel," i.e. small buds coming off of a central circle. Much larger than RBCs Symptoms: Disseminates and causes cervical, axillary, and inguinal LAD. Progresses to the lungs and causes granulomas. Will also present with mucocutaneous lesions Treatment: Itraconazole for mild infections, amphotericin for severe infections

Answer 8

ssRNA negative sense. Recall that it replicates in the cytoplasm and is enveloped. Spread via respiratory droplets. MMR live attenuated vaccine is used to Measles Symptoms of measles include the four "C's", which are cough, coryza (acute inflammation of the mucous membranes of the nasal cavity, aka stuff nose), conjunctivitis, and Koplik spots. Fever. After Koplik spots, couple days later will develop maculopapillar rash, starting behind the ears and face and then descending. This wash will become confluent (come together) Major complications include viral or bacterial pneumonia, subacute sclerosing panencephalitis (SSP) which lacks any treatment but diagnosed by Abs in the CSF Virulence factors: HA and Fusion protein which plays a role in creating syncycia (multinucleated giant cells) Vitamin A reduces measles morbidity and mortality Mumps Replicate in the salivary glands, particularly the parotid glands, leading to parotitis, and testes, which can cause inflammation of the epididymis (Orchitis, unilateral). Can also replicate in the CNS, can cause meningitis. Associated with HA, NA, and Fusion protein Respiratory Syncytial Virus (RSV) Seen in infants less than six months of age. Attaches to G protein of respiratory epithelial cells. Most common cause of bronchiolitis and pneumonia in infants. Associated with Fusion protein. Treat with Ribavirin in adults. Prevent infants (particularly pre-term) who are susceptible with Palivizumad which is an antibody against the fusion protein Parainfluenza Virus Cause of Croup, also known as laryngotracheobronchitis (seal bark cough and inspiratory stridor, high pitched breath sound from turbulent flow in the airway). Common presentation on X-ray is the narrowing of the subglottic region known as the "steeple sign" Adults simply present with a bad cold Associated with Fusion protein, HA, and NA

Answer 9

ssDNA virus (only ssDNA virus), naked virus. It is the smallest DNA virus known Transmitted via respiratory droplets and vertically (TORCHES). In the congenital version, causes hydrops fetalis in utero Causes Slapped Cheek Fever/Fifth Disease (five fingers to a slap)/Erythemia Infectiosum: Rash starts on the face and moves downward. In adults (classic case is school teacher presenting with the following symptoms), presents with joint pain, arthritis, and edema Can cause aplastic anemia (depletion of the bone marrow, leaving behind only the adipocytes giving the bone marrow a cobb-webbed look) in sickle cell patients

Answer 10

Positive RNA family (pico = small), naked viruses (lack viral envelop), transmitted via fecal-oral route with the exception of Rhinovirus (respiratory spread) Positive sense RNA uses host machinery to make protein Protein is made as a polyprotein product that's cleaved into smaller proteins Positive sense RNA replicate outside of nucleus because host cell mRNA which is analogous is processed in the cytoplasm Members: Rhinovirus, HepatitisA, Enteroviruses

Answer 11

Causes the mosquito borne illness Malaria, characterized by fever and headache, as well as anemia and splenomegally Identified by blood stain and Giemsa stain to see the parasites within RBCs Malaria carried by anopheles mosquitios that carry the sporozoites. Once the bug bites, mature to trophozoites in the liver. Eventually, schizont divides into merozoites which burst from hepatocyte and infect RBCs. In the RBC, trophozoite becomes a schizont again, then merozoite, and then then go in to infect more RBCs. Immature schizont has a ring form in the RBC. Merozoites can also form gametocytes, which are the sexual form. The cycle of the parasite is continued when a mosquito bites an infected host and takes in RBCs containing gametocytes Malariae Quartan fever cycle (ever 72 hours) Vivax and Ovale Produce dormant forms in the liver called hypnozoites. Follow tertian cycle (every 48 hours) Falciparum Most severe form of malaria and causes irregular fevers. May also have neurological involvement if parasitized RBCs occlude capillaries in the brain, as well in the kidneys and lungs. Banana shapes in the peripheral blood smear Treatment Chloroquine, works by blocking plasmodium heme polymerase. Primaquine to treat the hypnozoites in the liver. Be aware to check for G6PD deficiency in patients as these drugs may induce anemia. Or mefloquine, as many strains are resistant to chloroquine, and useful prophylactic drug for travelers in chloroquin resistant areas. Can also treat with atovaquone/proguanil together for travelers For infections by Falciparum, treat with artemisins, and possibly atovaquone/proguanil For very severe malaria infections, use IV artesunate or IV quinidine (unfortunately has causes cinchonism as a side effect, including tinnitus) Note, sickle cell disease is protective against P. falciparum

Answer 12

Immunocompromised individuals are the only ones that show signs of infection when Pneumocystis is present. One of the AIDS defining illnesses (similar to Candida esophagitis), presents when CD4 count drops below 200, and also the value at which you start prophylaxis Causes a diffuse interstitial pneumonia. Coughs won't be productive like bacterial pneumonia, nor will they show consolidations on X-ray either (may not show anything). If you see anything, will see ground glass X ray infiltrates PCP diagnosis can be confirmed with bronchoalveolar lavage (BAL). Then, with the BAL sample, you'll stain it with methamine silver to identify PCP, which will look like disc shaped yeasts Treatment/Prophylaxis: Both cases you give Bactram, which is combination trimethoprim/sulfonamide (sulfamethoxazol). If patient is allergic to sulfa drugs, treat with pentamidine

Answer 13

Positive RNA in picornavirus family (small RNA), naked virus (like all picornaviruses). Acid labile and can grow at 37C (in GI). Proliferate in lymphoid tissues (such as Peyer's pathes) and then spreads to the anterior horn motor neuron bodies, causing paralysis Causes polio, which leads to asymmetric paralysis, myalgia, and deep tendon reflex loss. Can leads to respiratory loss as well as it ascends. Like the other enteroviruses, polio is the leading cause of aseptic viral meningitis, marked by low glucose, no bacteria, and high protein levels in the CSF No treatment, but preventitive. Salk: killed polio vaccine. Sabin: live attenuated vaccine given orally Killed bypasses GI, so it doesn't form IgA antibodies, only IgG, which isn't ideal because we want IgA to protect at mucosal surfaces, live vaccine does produce IgG and IgA. Downside of live one is that it can shed in feces and infect someone else, causing paralysis

Answer 14

These viruses are naked dsDNA viruses with circular genome. JC Virus JC stands for John Cunningham virus and is the cause of progressive multifocal leukoencephalopathy (PML).PML is a demyelinating disease that kills oligodendrocytes that produce myelin for the CNS. Progesses to the point where most patients who get it die with months. Would see non-enhancing multifocal brain lesions in the white matter of the brain. Half the population has it, but asymptomatically. Typically only affects people who are immunocompromised, or HIV patients with less than 200 CD4 count. BK Virus Causes nephropathy and other diseases of the urinary tract including hemorrhagic cystitis (similar to adenovirus, its urine in the blood and bladder pain) however this is more implicated in transplant patients (name actually comes from the initials of a transplant patient whose urine was isolated)

Answer 15

DNA virus. Enveloped. Largest known DNA virus What is unique about this virus is that it is packaged with all machinery necessary for its replication: make their own envelopes, only DNA virus that replicates in the cytoplasm, DNA dependent RNA polymerase (which is why it doesn't need to go to nucleus) Will form intracytoplasmic inclusions at sites of their replication called Type B, or Guarnieri Bodies Dumbbell shaped core Smallpox Also known as variola, causes raised blisters on the skin. Important to distinguish between chicken pox (varicella zoster). Smallpox lesions will all be the same age (same maturity) whereas chicken pox age varies (blisters, healing blisters, and small scabs). Eradicated, and we no longer vaccine (used cowpox virus prior). Can be used as a bioweapon as it exists in labs Cowpox Transmitted via infected cow utters. This was the virus used for the smallpox vaccine, which lead to its eradication Molluscum contagiosum Causes flesh-colored, dome-shaped, umbilicated (little dimple in the middle) skin lesions which look like a snail's shell. Most common found in children typically on the trunk. In healthy adults, will cause single, focal lesion. However, in HIV infected adults will lead to diffuse molluscum contagiosum

Answer 16

dsRNA virus (only one), so no +/- classification. Replicates in the cytoplasm, nonenveloped. Segmented (BOAR - bunya, orthomyxo, arena, reo) with between 9-11 segments depending on the virus Rotavirus Transmitted oral-fecal route and causes toxin-mediated, explosive diarrhea, watery similar to norovirus. Caused by NSP4 encoded on the viral genome, increases chloride permeability leading to more secretions by gut epithelium. Seasonal virus, typically in the wintertime. Chilren are at high risk, especially in infants and children in daycare settings Treatment: Supportive care via oral rehydration. Vaccine: Live attenuated virus, taken orally. First dose given before three months of age due to increase side effects and decreased efficacy (causes telescoping of the bowel, known as intussusception) Colorado Tick Virus Causes fever, myalgia, vomiting

Answer 17

ssRNA negative sense virus, enveloped virus. Hallmark of Rhabdovirus is that it looks bullet shaped on EM. Also has a helical capsid Carried in rodents such as foxes, skunks, and bats (top carries in the US) The virus has a glycoprotein that binds to the nicotinic ACh receptors in the post-synaptic membrane at the NMJs. In these cells, they replicate. After incubating for weeks, it travels retrograde up neurons to the dorsal root ganglia. As it spreads initially, it causes tingling and muscle spasms. However, upon reaching the salivary glands causes increase salivation and excruciating spasm of throat and larynx, causing dysphagia. Finally, leads to high fever, encephalitis, neuronal death, and is invariably fatal. Diagnosed clinically, based on past exposure, or by biopsy/autopsy by finding Negri-bodies which are eosinophilic inclusions in neuronal bodies in the hippocampus pyrimidal cells or cerebellum Purkinje cells Treatment is with human Ig against the virus and giving the viral vaccine (killed virus). Give treatment even if not sure if you got bit as after symptoms present it's too late

Answer 18

Family: Picornavirus, small RNA virus, +ssRNA, nonenveloped Cause of the common cold. Acid labile, unique to Rhinovirus in picornavirus. Spread via respitory transmission or fomites (bad hands). Enters via host cells on ICAM-1 Grows best in 33, cooler than most viruses, why it ends up in URT 113 serotypes, so many different flavors, which is why it's hard to vaccinate so explains why there's no vaccination for Rhinovirus and it can't be treated with

Answer 19

Cutaneous mycosis fungi. Found on rose thorns, tree bark, and other plants. Dimorphic fungus. Resembles cigar shape yeast under microscope Causes Rose gardener's disease (lymphocutaneous sporotrichosis), which is initiated by traumatic contact with one of the above plant life. The infection then spreads in an ascending pattern from the focal lesion along the path of draining lymphatics and presents as red bumps Culture is the gold standard of diagnosis, but biopsy of the lesion will show granulomas consisting of histiocytes, multinucleated giant cells, and cigar shaped budding yeasts Treatment: Itraconazole. Can also treat with saturated potassium iodide, but this is an older treatment

Answer 20

Positive sense RNA viruses, enveloped (hense the name toga), like other positive sense RNA viruses, they replicate in the cytoplasm. Similar to picornavirus, togaviruses produce polyprotein that is cleaved into functional proteins by proteases Arbovirus (arthopod-borne virus): No treatment, just protection from mosquitos Western, Eastern, and Venezuelan Equine Encephalitis Viruses: Cause encephalitis. Vaccine exists, but only for at risk patients Chikungunya: Causes fever and joint pain up to months-years. More serious in elderly and newborns. No vaccine or antivirals exist Rubella (German Measles) Childhood exanthem (widespread rash) Three separate presentations: congenital, childhood, and adult Childhood: Causes postauricular and occipital lymphadenopathy, maculopapular rash that begins on the face and spreads downward. Will also see fever and fatigue, and rash moves faster than Measles and is generally only around for three days. Spread via respitatory droplets Congenital: Because the virus can cross the placenta, can be born with virus and have distinct symptoms: mental retardation, microcephaly, blindess, deafness, cataracts, jaundice, Patent Ductus Arteriosus, Pulmonic Stenosis, Purpuric Blueberry Muffin Rash, and Radiolucent Bone Lesions Adult: Lymphadenompathy and fever, but will also see arthralgia and arthritis. Rubella has no treatment, but is covered by the MMR (Mumps, Measls, Rubella) Live Attenuated Vaccine that produces both humoral and cell mediated immunity (but women who are planning on getting pregnant or immunecompromised should avoid getting). Also, common in immigrants as they may not have been vaccinated

Answer 21

Particularly of interest for (at risk for transplacental transfer) and immunocompromised patients. It is an intracellular parasitic protozoan that can infect any warm blooded animal. Carried by 30% of individuals world wide asymptomatically Transmitted via contaminated meat that contains toxo tissue cysts, or by water/vegetables that are contaminated by oocytes shed in the feces of infected animals, or mother-to-fetus if the mother is exposed during pregnancy (one of the TORCHES infections, is the T). Commonly, it is spread via cat feces In immunocompromised patients, Toxo will cause ring enhancing lesions on CT or MRI of the brain, encephalitis. May have to do brain biopsy to differentiate from CNS lymphoma. Can also develop chorioretinitis Congenital toxo causes intracranial calcifications, hydrocephalus, seizures, and chorioretinitis. Can also present with deafness Diagnosis: done by serology (doesn't always indicate active infection, and large majority of population has been exposed to toxo in the past) or biopsy (looking for intramuscular cysts) Treatment: sulfadiazine and pyrimethamine. Also, need to give prophylaxis for HIV patients when their CD4 count drops below 100 and IgG is positive for toxo: TMP/SMX (Bactram)

Answer 22

DNA virus of the Herpes virus family. Like all Herpes viruses, it is an enveloped virus. Like other Herpes viruses, able to stay latent: remains latent in dorsal root ganglia. Reactivation dependent on stress, aging, or immunocompromised state. This leads to the Herpes zoster, better known as Shingles, form. TORCH infection Chicken Pox Transmitted via respiratory droplets or by ruptures of the vesicles directly. Cause of chicken pox, which presents with fever, headache, vesicular (dew drops on a rose) rash similar to HSV. These lesions will also be at different stages, unlike smallpox where all blisters are the same stage. In adults, VZV can cause pneumonia (main cause of morbity in adults) and encephalitis (especially in the immunocompromised) Can use Tzank smear to screen for multinucleated giant cells (similar to HSV) Vaccine: Live attenuated vaccine for children Treatment: acyclovir for children ages >12, adults, and immunocompromised Shingles Also known as Herpes zoster, has dew drop on a rose appearance with dermatomal distribution (makes sense because residing in the dorsal root ganglia, when reactivated it will go towards the dermatome its nerve is supplying). Rarely crosses the midline, however when it does referred to as disseminated VZV (red flag that a person is immunocompromised). These rashes are incredibly painful, and can remain so after the rash subsides (postherpetic neuralgia) Can also be found in the trigeminal nerve if immunocompromise, leading to Herpes Zoster Opthalmicus, which is vision loss if V1 is affected Vaccine: recommended for adults over 60, also live attenutated Zoster vaccine. Keep away from immunocompromised patients, can give to HIV as long as CD4 greater than 200 Treatment: can also give acyclovir, or more commonly given is Famciclovir. Can also use valacyclovir. Congenital Varicella Syndrome Since VZV is a TORCH infection (as are all Herpes viruses), can cause birth defects. Limb hypoplasia, cutaneous scarring in dermatormal pattent, and blindness

Viruses and Eukaryotes Flashcards

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