Virology

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VM 607 Final Flashcards on Virology, created by Michelle Beermann on 14/12/2016.
Michelle Beermann
Flashcards by Michelle Beermann, updated more than 1 year ago
Michelle Beermann
Created by Michelle Beermann almost 8 years ago
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Question Answer
Coronaviruses Enveloped with S protein projections ss (+) RNA virus Very large genome FECoV, CCoV, TGEV, PRCV, PEDV, SDC, IBV, BCoV, SARS, MERS
FECoV Feline Enteric Coronavirus diarrhea Type II serotype is recombinant with CCoV Cell tropism: respiratory epithelium and enterocytes
FIP Point mutation of FECoV results in FIP Cell tropism: macrophages and monocytes Wet (T 3 HST): Weak CMI, strong humoral Dry (T 4 HST): Partial CMI response , humoral immunity
TGEV Transmissible gastroenteritis virus (coronavirus) Pigs Villous atrophy Diarrhea Secretory IgA important (oral vx, passive immunity)
PRCV Porcine Respiratory Coronavirus (PRCV) Mutation (Deletion) of TGEV Cell tropism: respiratory epithelium and alveolar macrophages Cross protection against TGEV
Avian infectious bronchitis virus (IBV) Coronavirus "Gasping disease" Exudate in respiratory tract
BCoV Bovine Coronavirus 3 manifestations: Neonate diarrhea Winter dysentery Respiratory disease
Orthomyxoviridae (Influenza) Enveloped ss (-) RNA virus 8 segments
Sialic acids and receptor preference Birds: 2,3 linkages Humans: 2,6 linkages (2,3 in lower resp.) Pigs: both 2,3 and 2,6 (pigs are a "mixing vessel")
Influenza envelope glycoproteins HA (hemagglutinin) and NA (neuraminidase) 18 H types 11N types
Influenza virus entry/uncoating 1) HA binds sialic receptor (receptor-mediated endocytosis) 2) Endosomal pH is low, protons pumped through ion channel it the virus 3) change in pH causes cleavage of HA into HA1 and HA2 4) Cleavage exposes the hydrophobic portion (fusion peptide) 5) Fusion peptide fuses with the endosomal membrane 6) inner components (RNP) of virus released
Influenza: HA protein The most important pathogenic determinant *determines cell tropism *determines host spp.
Antigenic drift Non-lethal point mutations accumulate by nucleotide substitutions -Frequently in theHA gene -Accumulation of mutations within one serotype -Changes is epitopes -->Escape from neutralization--> recurrent infections
Antigenic shift Genome segment exchange *Co-infection resulting in genetic reassortment Explains seasonal epidemics and flu vaccine updates
Avian influenzas found in humans H5N1, H7N9, H9N2
Circulating types of influenza A found in humans H1N1 and H3N2
Immune response to influenza Not cross protective CMI: important for recovery and limiting further spread Humoral: short duration of Ab; problems with Ag shift/drift
Influenza: spread Virus enters respiratory epithelium Apical release --> re-entry = Local spread Basal release --> L. nodes= systemic spread
SIV Swine Influenza virus Circulating: H1N1 and H3N2 Do not usually infect humans
AIV Avian influenza virus -HPAI (reportable) -LPAI
LPAI Low Path. Avian Influenza Localized infection Usually only mild signs
HPAI High Path. Avian Influenza (reportable) "Fowl Plague"= H5N1 H5 or H7 serotypes Systemic Acute respiratory disease and severe generalized disease Resp. distress, diarrhea, edema of head
EIV Equine influenza Virus H7N7 (equine 1) and H3N8 (equine 2) Only H3N8 circulating Endemic in US Flu-like signs (fever, cough, runny nose, sore muscles) Diff: EHV-4, EAV, equine rhinovirus
CIV Canine Influenza Virus H3N8 equine virus Cough, runny nose, fever No disease in humans
Arteriviruses Enveloped ss (+) RNA virus Large genome Cell tropism: monocytes/macrophages
EAV Equine Arteritis Virus (Arterivirus) Subclinical to acute febrile disease (flu-like) Abortion in pregnant mares Stallions are carriers, shed virus in semen
EAV: tissue tropism Primary replication in alveolar macrophages --> viremia --> Monocytes of arterioles --> vasculitis, edema, hemorrhage
EAV: Transmission Respiratory Venereal
PRRSV Porcine Reproductive and Respiratory Syndrome Virus (Arterivirus) c/s: stillborn/abortion; blue ears (cyanosis); interstitial pneumonia; "thumping" High morbidity and mortality
PRRSV: tropism Porcine alveolar macrophages (PAM) --> infects L. nodes --> viremia
PRRSV: transmission Horizontal: respiratory, fecal/oral, direct contact Vertical: transplacental, semen, AI
Bunyaviruses Enveloped ss (-) RNA virus 3 segments arboviruses (except Hantavirus = rodents)
Hantavirus Bunyavirus reservoir: rodents Zoonotic 2 forms in humans: -Hemorrhagic fever and renal syndrome (HFRS) -Hantavirus pulmonary syndrome (HPS)
Rift Valley Fever Virus Bunyavirus Foreign Sheep and Cattle (abortion, fever, epistaxis, acute death)
Cache Valley Disease Bunyavirus Mosquito borne Sheep Neuro-invasive Teratogenic (arthogyrposis)
Schmallenberg Virus (SBV) Bunyavirus Foreign Sheep, goats, cattle Teratogenic Transmitted by biting midges
Order: Mononegavirales ss (-) RNA viruses -Paramyxoviruses -Filoviruses -Rhabdoviruses
Paramyxoviruses Enveloped Pleomorphic ss (-) RNA Helical nucleocapsid
Paramyxovirus: RNP Ribonucleoprotein complex N (nucleocapsid) + L (polymerase) + P (phosphoprotein) RNP released into genome directly (No endosome) - uncoating at cell membrane
Orthomyxoviridae Influenza virus
Paramyxovirus membrane proteins HN (hemagluttinin-neuraminidase) F (fusion protein)
Paramyxovirus: HN Hemagluttinin-neuraminidase Receptor determinant (triggers fusion) Binds to receptor on cell membrane
Paramyxovirus: F protein Fusion protein induces fusion of the viral and cell membrane ***Major determinant of virulence*** When HN binds to receptor, the conformation of F0 changes (cleaved into F1 and F2) --> exposes hydrophobic sequence
Paramyxovirus: syncytia formation Infected cell fuses with uninfected cells to form one multinucleated cell (via same fusion mechanism as entry/uncoating) Virus can disseminated from cell to cell w/o receptors
Newcastle Disease Virus (NDV) Paramyxovirus 1 serotype, 3 pathotypes Avian pneumovirus Pneumotropic and enterotropic
NDV: Lentogenic strain Pneumotropic pathotype of newcastle disease virus (Paramyxo.) Subclinical to mild disease Source for vaccines
NDV: Mesogenic strain Pneumotropic pathotype of newcastle disease virus (Paramyxo.) Intermediate virulence, low to moderate mortality
NDV: Velogenic strain Enterotropic pathotype of newcastle disease virus (paramyxo.) REPORTABLE Exotic Newcastle disease (END) Respiratory, GI, and neuro signs (necrosis) -edema of head -torticollis
CDV Canine Distemper Virus (Paramyxo.) **Immune status of animal determines disease progression
CDV: Clinical signs Fever Ocular/nasal discharge Anorexia **Thrombocytopenia **Leukopenia Hyperkeratosis CNS involvement (*Old dog encephalitis)
CDV: pathogenesis 2 days post exposure: replicates in bronchial L.nodes and tonsils 4 days: in mononuclear cells of L.nodes, GI, respiratory tracts 7-9 days: Epithelial cells 9+ days: CNS
CDV: diagnosis Inclusion bodies in cytoplasm and nucleus
CDV: transmission Virus shed in nasal and ocular secretions, excreted in urine and feces
CDV: vaccination MLV 1st @ 8 weeks age 2nd @12-16 weeks
BRSV Bovine Respiratory Syncytial Virus (Paramyxo.) Acute lower respiratory Tract infection Pneumonia in calves
PI-3 Bovine Parainfluenza Type 3 Virus (Paramyxo.) SHIPPING FEVER polymicrobial infection agent More of an upper respiratory disease
PI-3 Transmission and tropism Aerosols Targets epithelial cells of the respiratory tract and alveolar cells
PI-2 Canine Parainfluenza Type 2 Virus (Paramyxo.) KENNEL COUGH (infectious tracheobronchitis) organism Localized in upper respiratory tract
Rinderpest Paramyxovirus Reportable Foreign Eradicated
Morbillivirus Paramyxovirus Marine mammals
Hendra virus Paramyxovirus High mortality in horses and humans Respiratory illness Zoonotic (but not dogs, rodents, or chickens)
Nipah virus Paramyxovirus Encephalitis in humans Respiratory disease in pigs Reservoir: flying foxes
Rhabdoviruses Enveloped ss (-) RNA Bullet shape 1 serotype 8 ecotypes 5 varients depending on N protein Monoclonal antibody (MAb) reactivity patterns
Rhabdovirus: surface protein G protein (neutralizing protein -- used for vaccines) plays role in pathogenicity and inducing immune response
Rabies Rhabdovirus All warm-blooded animals Severe, usually fatal disease of CNS Incubation 1-3 months
Rabies: clinical signs 1. Prodromal stage: minor behavior changes, clinical signs not obvious 2. Furious stage: severe agitaiton, aggression, loss of fear, convulsions, death 3. Paralytic (dumb) stage: unable to swallow, frothing, hindlimb paralysis
Rabies: diagnosis NO VIREMIA Negri bodies- cytoplasmic inclusions bodies - may be present in neurons in brain
Rabies: replication Primary replication: at site of entry (non-neural tissue) Secondary replication: invades nerve endings through acetylcholine receptors in neurons and spreads to CNS
VSV Vesicular Stomatitis Virus (Rhabdovirus) Acute febrile disease of horses, cattle, swine Vesicles in oral mucosa/ tongue REPORTABLE
VSV: transmission Vesicular Stomatitis Virus (Rhabdovirus) Direct contact (saliva); insects (mosquitos, sandflies)
Reoviruses REO- virus (Respirator Enteric Orphan virus) Non-enveloped ds RNA virus 11 segments Wheel-like
Reovirus: proteins 3 layers 1. Outer capsid: VP7, VP4 (evokes neutralizing Ab) 2. Inner capsid: VP6 (strong immunogen) 3. Core: VP1, VP2, VP3
Reovirus: Serotypes P: minor neutralization VP4 Proteolytically cleaved G: major neutralization VP7 Glycoprotein
Reovirus: Serogroups Determined by VP6 Group: A most prevalent and clinically important Group B: humans Groups C and E: swine Groups D and F: fowl
Birnaviruses Bi-RNA-viruses Non-enveloped ds RNA virus 2 segments
Rotavirus Reovirus Diarrhea in various spp. Most common cause of diarrhea in calves and lambs *Time diarrhea occurs is dependent on immune status of mother and absorption of colostral Abs
Rotavirus: cell tropism enters columnar epithelial cells a the apical half of intestinal villi Jejunum and ileum
Rotavirus: enterotoxin NSP4 enterotoxin increases intracellular [Ca2+] and Cl- secretion from crypt cells --> secretory diarrhea
BTV Bluetongue Virus (Reovirus) Sheep and Deer mostly Arbovirus (biting midges) Edema, hemorrhage, and mucosal ulceration throughout the body Similar to Epizootic Hemorrhagic Disease
Infectious bursal disease (Birnavirus) Prolonged immunosuppression in chickens Replicates in dividing, pre-lymphocytes in cloacal bursa (swollen and hemorrhagic) B cell deficiency Petechial hemorrhage in leg and thigh
Infectious pancreatic necrosis virus (Birnavirus) Disease of salmonid fish less than 6 mo. High mortality Petechial hemorrhage within pyloric and pancreatic tissues
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