Microbiology - Block 1 - Part 2

davidwurbel7's version from 2015-05-31 01:54

Enveloped +RNA Virus

Question Answer
Second most common cause of the cold and cause of SARSCoronavirus
Causes URTI (mild), & usually there is no fever, & coughs and sore throat are rareCoronavirus
Clinical presentation atypical pneumonia; History of exposure (China or Toronto) Fever > 100.4 F, chills & rigors, flu like illness, dizziness, dry cough, dyspnea and progressive hypoxia. Chest X ray shows patchy distribution of focal interstitial infiltrates; Diarrhea (10% mortality with diarrhea)SARS - CoV
Enveloped+ ssRNA; Patient is unvaccinated; Fever; Coryza (running nose), Conjunctiva, Cough; Rash is fine, pink, discrete erythematous maculo papular rash; Appear first on face, then spreads to the trunk and limbs - Fade after 72 hrs or lessRubella
URTI is mild with low grade fever without rash for 7 days; then rash with URTI is mild with low grade fever for 3 daysRubella
"R" in the TORCHeSRubella
Prevented by attenuated MMRRubella
Crosses placenta when “sero-negative” mother has primary infection; Cataracts; Mental retardation; Microencephaly; Deafness; Heart- PDA Patent ductus arteriosis; Thrombocytopenic purpura (“Blueberry Muffin Baby”)Congenital Rubella
Enveloped, SS + RNA Virus; Transmission by insect vector (mosquitoes); "Arbovirus” Arthoropod BorneTogavirus or Flavivirus
Includes WEEV, EEEV, VEEV and ChikagunyaTogavirus
Includes West Nile, St. L. Encephalitis, Dengue, Yellow FeverFlavivirus
The mosquito vector for West Nile, St. L. Encephalitis, WEEV, EEEV and VEEVCulex
The mosquito vector for Chikagunya, Dengue and Yellow FeverAedes
Mild illness often have only a headache and fever. More severe disease is marked by fever, headache, neck stiffness, stupor, disorientation, coma, tremors, occasional convulsions (especially in infants) and spastic (but rarely flaccid) paralysisSt. Louis Encephalitis
Serious illness with high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysisWest Nile Fever
Flu-like symptoms with severe joint pain. High fever, headache, rash, and back and bone pain that last 6-7 daysDengue Fever
Characterized by fever, hemorrhagic manifestations, thrombocytopenia and leaky capillaries, as well as muscle and bone pain. In many cases there is a rashDengue Haemorrhagic Fever
Characterized by fever, hemorrhagic manifestations, thrombocytopenia and leaky capillaries, as well as muscle and bone pain. In many cases there is a rash, hypotensionDengue Haemorrhagic Shock Syndrome
Jaundice, GI bleeding (GI) “Black vomit”, can eventually lead to shock and failure of multiple organs; live attenuated vaccine availableYellow Fever


Question Answer
Enveloped ss+RNA includes reverse transcriptase, integrase, protease; transmission by blood exposure (IV drugs, transfusion, needles), sexual exposure and vertical (mom-to-baby) Targets macrophages and T cells (M-tropic =CCR5/CD4)(T-tropic = CXCR4/CD4) and establishes latent infection in CD4+ T cellsHIV
Diagnosis early by p24 ELISA; Screened for by Anti-gp120 IgG ELISA and confirmed by Complete WesternHIV
The surface VAP proteins are gp 120 and gp 41HIV
Gp120 first binds to _______ and co-receptors _______ (memory CD4 T cells, DCs and macrophages) – M tropicCD4 and CCR5
Gp120 later binds to _______ and ________ (activated T cells) - T tropicCD4 and CXCR4
Causes the fusion of viral envelop with cell plasma membraneGp41
Converts RNA into single-stranded DNA and then again into double-stranded DNAReverse Transcriptase
Inserts viral DNA into host genomeIntegrase
Cleaves the polyprotein after budding to produce a mature virionProtease
Initial infection of HIV infection vrial load is high and CD4+ T cells initially drops but rebounds; Patient is symptomatic with flu-like symptoms and infectiousStage 1
Latent phase of HIV infection in which viral load is low and CD4+ T cells is high with occasional spikes of viral load; Patient is asymptomatic but infectiousStage 2
CD4 cell count is between 200-500/mm3 or increased level of virus; Positive Ab tests and negative skin tests that require T cell activity; Weight loss (10% body weight), constant low-grade fever, night sweats, continual diarrhea, and extreme fatigue; may have Candida oral thrush; Patient is symptomatic and infectiousStage 3
CD4 cell count decreases to less than 200/mm3; Antibody test is often negative; Occurrence of indicator diseases; Kaposi sarcoma (nonhodgkin lymphoma & other), thrush, Specific opportunistic diseases (Pneumocystis pneumonia, Mycobacterium avium intracellulare complex; Severe CMV diseasesStage 4 (AIDS)
Screening test for HIV antibodies; Inexpensive but error proneELISA
Secondary test for HIV; Electrophoretic separation of viral proteins and detection of antibody to specific proteinsComplete Western Blot
Most sensitive test for HIV; Gives the actual number of HIV moleculesqRT-PCR

HIV Treatment Medications

Question Answer
Zidivudine, stavudine, lamivudine, abacavir, zalcitabine, emtricitabine, didanosineNucleoside Reverse transcriptase inhibitors (NRTI)
-udine medicationsNucleoside Reverse transcriptase inhibitors (NRTI)
Efavirenz, nevirapine, delaviridine, etravirineNon-nucleoside RT’s Inhibitors
-ine medication Non-nucleoside RT’s Inhibitors
TenofovirNucleotide RT’s inhibitors
-fover medicationsNucleotide RT’s inhibitors
Ritonavir indinavir, nelfinavir,, saquinavir, lopinavir, darunavirProtease Inhibitors
-navir medicationsProtease Inhibitors
EnfurvitideFusion Inhibitors
RaltegravirIntegrase Inhibitors
-gravir medicationsIntegrase Inhibitors
MaravirocCCR5 Inhibitors
Highly Active Antiretroviral Therapy; uses combination therapy of drugsHAART

Anti-Viral Agents

Question Answer
Attactment inhibitor that binds to CCR5 and block the interaction of gp120Maraviroc
Nucleoside analogue with modified nucleoside bases; Example RibavirinNucleoside RNA Polymerase Inhibitors
Analogue of guanosine but base ring is incomplete and open & inhibit nucleotide biosynthesis; only used in life-threatening situations; Target: HepC, RSVRibavirin
Nucleoside analogues with modified sugar residues; Ends with –LOVIRNucleoside DNA Polymerase Inhibitors
Works by preventing elongation by Herpes DNA polymeraseAcyclovir
Nucleoside analogues with modified sugar residues; Ends with –FOVIR and -UDINENucleoside Reverse Transcriptase Inhibitors (NRTI)
Examples of this class of anti-virals are Tenofovir, Zidovudine (AZT) and LamivudineNucleoside Reverse Transcriptase Inhibitors (NRTI)
Directly binds to HIV Reverse Transcriptsase; Examples include Nevirapine, Delaviridine and Efavirenz Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTI)
Prevent integration of HIV cDNA of HIV into host chromosome by directly inhibiting Integrase; Examples include Raltegravir & ElvitegravirIntegrase Inhibitors


Question Answer
Naked + ssRNA in the Picorna family; only 1 serotype; Transmission by Fecal-oral, Consuming shellfish, Requires CTL-mediated lysis; Common in day care centers; Associated with Shellfish *conch*; Anti-HAV IgM = active infection, Anti-HAV IgG = immunity; Treatment & Prevention - Killed/inactivated vaccine for >1 year oldsHepA (HAV)
Naked + ssRNA in the Hepe family Fecal-oral transmission, contaminated water; Replicate in hepatocytes (no latent infection), High incidence in Central AsiaHepE (HEV)
In normal individuals - mild acute hepatitis with no chronic state; in pregnant women is associated with Fulminant hepatitisHEV
Enveloped + ssRNA in the Flavi family; Genotype 1 is least responsive to treatment and has a poorer prognosis; Transmission is by blood exposure or by transfusion or transplant prior to 1992; Establishes chronic infection (90%), Triggers cirrhosis, HCC (Alcohol is a major factor for accelerated disease progression); Diagnosis - Anti-HCV IgG is suggestive of immunity. qRT-PCR is definitive; Treatment & Prevention - Interferon-α/RibavirinHepC (HCV)
Enveloped dsDNA in the HepadnaHepB (HBV)
Enveloped – ssRNA in the Delta familyHepD (HDV)
Symptoms include Fever, anorexia, nausea, vomiting, jaundice, abdominal swelling, right upper quadrant (RUQ) pain, dark urine, pale feces, Icterus, Hepatomegaly, ALT: >100 U/L; AST: >100 U/LHepatitis
Most cases of hepatitis resolves, always withHAV.
Chronic infection with leads to fibrosis, cirrhosis and hepatocellular carcinoma (HCC)HBV and HCV
Acute liver failure that is rare fatal rapid deterioration of liver associated with toxic encephalopathy. Transplant is only treatment.Fulminant Hepatitis
Enveloped partial dsDNA; HBsAg=Surface; HBcAg=Core; HBeAg=Extracellular intermediate - Encodes Reverse Transcriptase; Transmission by Blood exposure, Sexual, Vertical (mom-to-baby); Pathogenesis;Targets hepatocytes; Establishes chronic infection (10%); Triggers cirrhosis, HCC; Clinical; Presentation - Fever and general malaise, Jaundice, Dark urine, Icterus; Diagnosis - HBsAg + HBeAg = active infection, Anti-HBc IgM = primary infection, Anti-HBc IgG = Past/chronic infection, Anti-HBs IgG = Immunity, Ground glass hepatocytes; Treatment & Prevention - Interferon-α (chronic), Lamivudine/Adefovir (chronic), Passive IgG (neonates), Subunit vaccine = HBsAgHep B
HBsAgSurface antigen
HBcAgCore antigen
HBeAgExtracellular form of Core Ag
The presence of HBsAg and HBeAg means that the infection isActive Infection
RT is target for treatmentLamivudine
Risk factors include IV drug use, Unprotected sex, Needle stick, Blood transfusion, Transplantation and Mom-to-babyHep B
HBV DNA can stabilize in nucleus leading to incorporation of DNA into host chromatin resulting inChronic Infection
Clinical Presentations - Acute hepatitis => Resolved (transient infection) in >90% of immuno-competent patientsHep B
Serum + HBsAg > 6 months and + HBeAg > 6 monthsChronic Persistent Hepatitis
Serum + HBsAg > 6 months and - HBeAg > 6 monthsChronic Carrier
Clinical complications - Glomerulonephritis - Hypersensitivity III reaction to HBsAg - Rash, bloody urine, fever; Polyarteritis nodosum - Damage to arteries from autoreactive immune cells; “beaded” aneurysms; fever, fatigue, weakness, loss of appetite, weight loss, muscle achesHep B
First to appear after primary infection ~2weeksAnti-HBcAg IgM
Shift from IgM to IgG occurs ~4-6 months after primary infectionAnti-HBcAg IgG
Protective antibody that appears ~5-9 months after primary infectionAnti-HBsAg IgG
Presence of HBsAg and Anti-HBc IgG and Absence of HBeAg"Healthy" Chronic Carrier
Presence of HBsAg and Anti-HBc IgG and Presence of HBeAgChronic Persistent Active
Antigen is undetectable and the antibodies for yet to develop to significant quantities to be detectableSerology Gap
Results from accumulation of HBsAg particle within hepatocytesGround Grass Hepatocytes
Ground Glass Hepatocytes (GGH) are unique indicatorChronic HBV
Pegylated interferon-α, Lamivudine (NRTi), Adefovir (NRTi) given only in cases ofChronic Hepatitis
Pegylated interferon-α, Lamivudine (NRTi), Adefovir (NRTi) given only in cases of chronic hepatitis with a risk ofLiver Damage
Hepatitis virus that cannot exist without HBsAgHDV
Contracts HBV and HDV simultaneously which results in acute resolutionCo-Infection
Chronic HBV and contracts HDV later which results in fulminant hepatitisSuper Infection


Question Answer
Enveloped ss-RNA Segmented; Orthomyxo Family; Types A(worst), B, C (minor); Hemagglutanin,Neuraminidase, M2Influenza
Targets sialic acid on epithelial cells of upper and lower respiratory tract. Desquamation of ciliated/mucus-secreting cellsInfluenza
Slight genetic change which can result in epidemicDrift
Major HA change which can result in pandemicShift
Complications include Viral pneumonia (ARDS) and Bacterial pneumonia (S.aureus)Influenza
Early treatment includes Amantadine/Rimantadine (A) and Zanamivir/Osetamivir (A/B)Influenza
Prevention (Annual) Attenuated vaccine or Killed/inactivated vaccineInfluenza
Haemagglutinin (HA) and Neuraminidase (NA) are ________ spikes located on the protein coat of InfluenzaGlycoprotein
Forms proton channel in membrane & promotes uncoating & viral genome release and inhibited by amantadine & remantadineM2
(Insert 15.6)
Question Answer
Has enzymatic activity (cleaves neuraminic (sialic) acid residue of the mucus and Important in releasing mature virus from cellsNeuraminadase (NA)
This is the target for 2 drugs (zanamivir & oseltamivir- tamiflu) which prevents the release of virion particlesNeuraminadase (NA)
RNA genes originating from different hosts (ie. Human virus and avian virus). Facilitated by genomic segmented structure & ability to infect human and animal speciesGenetic Re-assortment
Expression of new protein combination on progeny virion particlesPhenotypic Mixing
Abrupt onset of fever (usually high), chills, myalgia, fatigue, sore throat, & non-productive coughInfluenza
Complications of this virus include Acute Respiratory Distress Syndrome (ARDS); Secondary bacterial pneumonia - Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, MC cause of death in elderly; Myositis usually occurs in kids; Reyes syndrome (encephalitis, mortality rate 40%)Influenza
Targets M2 protein. Inhibit penetration by preventing uncoating. Type A only. High resistance in USARimantadine and Amantadine
Targets neuraminidase. Inhibit release of virion particle by preventing enzymatic cleavage of HA and sialic acid. Both Type A and B.Zanamivir and Oseltamivir (Tami-Flu)
-dine medication targetsM2
-mivir medication targetsNeuraminidase
Trivalent vaccine containing 2 strains of type A & one strain of type B (representing strain of the year, determined by WHO). Intranasal administration. More IgA generated, thus more mucosal protection. Ages 2-49 without complicationsLive Attenuated Strain (Flu-Mist)
Trivalent strain containing 2 strains of type A & one strain of type B (representing strain of the year, determined by WHO). Intramuscular administration. More IgG generated, thus protects against complications. Ages 6m-3yrs, >50yrs, high risk and healthcare workersInactivated Vaccine (Flu-Shot)