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Flashcards in (-) Strand RNA Viruses Deck (30)
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Define the functions of the 2 glycoproteins spikes in Influenza virus.

1. Neuraminidase = cleaves receptor so that when viral progeny leave, they won’t infect same cell
2. Hemagglutinin = enables virus to attach and enter host cell (Antibodies to this neutralize influenza)


List at least 3 helical (-) strand RNA viruses.

1. Filovirus
2. Rhabdovirus
3. Arenavirus


List the helical (+) sense RNA viruses

1. Poliovirus - respiratory paralysis
2. Coronavirus -SARS and MerS-COV


What are the 4 segmented RNA Viruses?

Bunyavirus, Orthomyxovirus (Influenza), Arenavirus, Reovirus


What are the 2 ways in which Influenza virus can mutate?

1. Antigenic Shift - reassortments responsible for PANDEMICS, responsible for recombination btw species (i.e. Avian, swine)
2. Antigenic Drift - point mutation that changes neuraminidase (NA) or hemagluttanin (HA) molecules, which is why we need a seasonal flu vaccine each year;
Both associated with Influenza A


Define hemagluttanin

Influenza glycoprotein that binds sialic acid on cell membranes of respiratory tract allowing them to enter the cell. HA also causes RBCs to aggregate in test tubes.


Define neuramidase

Influenza glycoprotein that cleaves sialic acid residues within infected host cells to allow newly formed virions to exit (bud off).
*Inhibited by Oseltamivir (Tamiflu)*


What is the significance of M2 protein in Influenza viruses?

Low pH (acidification) is needed to allow viral uncoating in endosome. *Amantadine and Rimantadine inhibit viral uncoating (no longer useful).*


What are the antigenic components of the anti-Influenza vaccine currently used in the US?

Inactivated virions of currently-circulating serotypes of Influenza A and B viruses.


What produces a pattern of worldwide Influenza epidemics at intervals every few decades? What is the significance?

Antigenic Shift = Genome segment re-assortment between human and avian-adapted viruses. These often produce more pathogenic, novel strains.


What is the diagnostic feature of Rhabdovirus? What is the most reliable diagnostic test of CSF and serum in an Rabies-infected person?

Eosinophilia Negri bodies at cytoplasm of neurons (pyramidal cells of Hippocampus and Purkinje cells). It’s best to stain the cells with direct fluorescent antibody technique to detect rabies antigens.


What are the treatment and prevention protocols for Rabies infection?

Human diploid cell culture KILLED vaccine and Active immunization via Human Rabies Immunoglobulin (HRIG)


Describe Filoviruses (type, replication, symptoms)

Negative-sense, helical capsid ssRNA viruses with “pleomorphic” shapes. Replicates in the cytoplasm. Petechiae rash and hemorrhagic fever. Transmitted by monkeys and bats. Highly enveloped


Describe Bunyavirus (type, transmission, symptoms)

Enveloped, segmented negative sense ssRNA virus.
Tsm: Mosquito (arthropod) vectors with wild rodent hosts (chipmunks, squirrels, rabbits).
Cx: Pulmonary capillary leak (edema)


List 2 well known arboviruses that fall within the Bunyavirus family. What are some clinical symptoms and the transmission?

California encephalitis and Rift Valley Fever
Cx: seizures and encephalitis
Tsm: Aedes mosquito


Describe Arenavirus (type, transmission, symptoms)

Segmented ssRNA virus, T-shaped glycoproteins but AMBISENSE genome. Rodent reservoir transmission. Lasso fever, Systemic Febrile illness, Lymphocytic Choriomeningitis Virus (LCV) = flu-like symptoms and self-limiting meningitis.


Describe Reovirus (type, transmission, example)

The ONLY dsRNA virus (both +/- sense) with 2 icosahedral capsids.
Ex: Rotavirus = explosive, watery diarrhea in children (from NSP4 toxin = inc Cl permeability);
Live oral vaccine


What do Mumps, Measles and Respiratory Syncytial Virus have in common?

These are Paramyxoviruses (with SEGMENTED genomes) that are form syncytial or multinucleated giant cells of the host cells they infect.


This negative-sense ssRNA virus has the following diagnostic features: Koplik spots on lateral buccal mucosa, maculopapular rash, >101 F fever and sore throat. What is it?

Measles virus - with a >95% preventive MMR vaccine (live attenuated strain)!!! Viremia follows initial viral infection.


This negative-sense ssRNA virus has the following features: #1 cause of viral LRT in infants/children, acute bronchialitis, results in multinucleated giant cells in mucus. What is it and how is it treated?

Respiratory Syncytial Virus - treated with RSV-IVIG, Palivizumab (IM monoclonal antibody) and Ribavirin aerosol


This negative-sense ssRNA virus has the following features: bullet-shaped, helical nucleocapsid, results in prodromal fever, progresses to CNS dysfunction then respiratory arrest. What is it and how is it diagnosed? What of prophylactic treatment?

Rhabdovirus (Rabies);
Dx: Negri bodies in cytoplasm of neurons;
Tx: 4-dose Killed vaccine and Human Rabies immunoglobulin (HRIG for post-exposure)


Define what occurs in Reye’s Syndrome (cause, effects)

Associated with children (aged 4-12) who take aspirin (instead of Tylenol) recently infected with Influenza B or Varicella. This results in acute brain damage and liver dysfunction.


What is the live attenuated Flu vaccine and how does it work?

FluMist is the intranasal spray that ideally increases IgA’s in people who take it (aged 5-47 years old)


Explain H1N1 (type, treatment)

Swine Influenza A (2009); novel strain with avian, swine and human subtypes; treated with oseltamivir (99%) and zanamirvir (100%);
*Also occurred as the 1918 Spanish Flu*


What is the glycoprotein spike that enables paramyxoviruses to form multinucleated giant (infected) cells?

Fusion glycoprotein (F) - forms syncytial


What negative-sense ss RNA virus has the following features: common LRT infections in children, causes syncytial formation, defined by a “croup” cough?

Parainfluenza (PIV 1-4) - transmitted by respiratory droplets.


What negative-sense ss RNA virus has the following features: swelling of parotid glands, upper respiratory tract infection, painful swallowing, orchitis (painful gonads)?

Mumps virus - prophylactic MMR vaccine and hyper immunoglobulin, can result in deafness if not treated


Describe the best way to reduce transmission of Ebola virus.

Use barrier methods to prevent contact with blood or body fluids of infected persons.


Define the mode of transmission for Hantavirus.

Inhalation of aerosolized rodent urine/feces, or of material contaminated with these.


Every RNA virus replicates in the ________ with the exception of _________ which replicates in _______

RNA viruses often replicate in cytoplasm; except Influenza (Orthomyxoviruses) that replicate in the nucleus.