Lecture 8 - Negative Strand RNA Viruses

<p>It bridges envelope glycoproteins to nucleocapsids. (C)</p> Signup and view all the answers

<p>Periodic spikes in EBOV antibodies months after recovery. (A)</p> Signup and view all the answers

<p>Recrudescence (A)</p> Signup and view all the answers

<p>Cellular proteins involved with trafficking and sorting of intracellular vesicles. (C)</p> Signup and view all the answers

<p>Vaccinating survivors to boost protective antibody responses. (A)</p> Signup and view all the answers

<p>It contains a promoter for viral RNA polymerase and packaging signal. (D)</p> Signup and view all the answers

<p>At the 3’ terminal of the RNA genome. (A)</p> Signup and view all the answers

<p>RNA polymerase transcribes a short sequence and terminates to release free leader RNA. (B)</p> Signup and view all the answers

<p>A 3’ polyA tail and a methylated 5’ cap. (B)</p> Signup and view all the answers

<p>During the assembly of the nucleocapsids. (C)</p> Signup and view all the answers

<p>Red highlighted proteins. (A)</p> Signup and view all the answers

<p>It occurs in the cytoplasm and uses the '-‘ sense RNA as a template. (D)</p> Signup and view all the answers

<p>It terminates to release a free leader RNA and scans for an mRNA start site. (D)</p> Signup and view all the answers

<p>Marburgvirus and Ebolavirus (B)</p> Signup and view all the answers

<p>Fruit bats (D)</p> Signup and view all the answers

<p>Negative sense single-stranded RNA (C)</p> Signup and view all the answers

<p>Transmission typically requires close contact. (C)</p> Signup and view all the answers

<p>Coughing (C)</p> Signup and view all the answers

<p>Seven (D)</p> Signup and view all the answers

<p>Up to 90% (C)</p> Signup and view all the answers

<p>Envelope glycoprotein (GP) (B)</p> Signup and view all the answers

<p>It changes the Thr to Asn and alters the reading frame. (B)</p> Signup and view all the answers

<p>Cytokine release (D)</p> Signup and view all the answers

<p>GP (A)</p> Signup and view all the answers

<p>Asialoglycoprotein receptor (D)</p> Signup and view all the answers

<p>Ebola virus causes severe hemorrhagic fever. (B)</p> Signup and view all the answers

<p>sGP (C)</p> Signup and view all the answers

<p>It cleaves GP into GP1 and GP2. (C)</p> Signup and view all the answers

<p>They mediate attachment and entry of the virus into cells. (D)</p> Signup and view all the answers

<p>Extensive glycosylation (A)</p> Signup and view all the answers

<p>It may lead to the generation of a smaller sGP. (C)</p> Signup and view all the answers

<p>They incorporate GP into the envelopes of unrelated recombinant viruses. (D)</p> Signup and view all the answers

<p>Disulfide bridge (D)</p> Signup and view all the answers

<p>80-120 nm (C)</p> Signup and view all the answers

<p>Hemagglutinin (HA) and neuraminidase (NA) (B)</p> Signup and view all the answers

<p>Thogotovirus and Isavirus (D)</p> Signup and view all the answers

<p>The elderly, infants, and the chronically ill (B)</p> Signup and view all the answers

<p>They lead to sporadic pandemics and regular epidemics in winter. (A)</p> Signup and view all the answers

<p>20,000 deaths (A)</p> Signup and view all the answers

<p>Secondary bacterial infections (B)</p> Signup and view all the answers

<p>Threat of another human pandemic (C)</p> Signup and view all the answers

<p>A low pH-triggered fusion within vesicles (C)</p> Signup and view all the answers

<p>sGP is released from infected cells and can serve as a biomarker. (B)</p> Signup and view all the answers

<p>It may limit GP cytotoxicity, leading to more efficient replication. (C)</p> Signup and view all the answers

<p>The proteins highlighted in blue (B)</p> Signup and view all the answers

<p>The C-terminal fragment of the glycoprotein involved in fusion (A)</p> Signup and view all the answers

<p>They are largely associated with the viral genome or nucleocapsid. (B)</p> Signup and view all the answers

<p>By binding to antibodies and targeting host defense elements (D)</p> Signup and view all the answers

<p>Various vectors must be co-transfected for proper study. (B)</p> Signup and view all the answers

Spread of filovirus infections between humans is primarily through close contact with bodily fluids (blood, feces, vomit, etc.).

Filoviruses likely jump to primates from fruit bats.

Ebolavirus species are named after the location where they were first discovered (e.g., Bundibugyo, Zaire).

Filoviruses have a linear, negative-sense, single-stranded RNA genome.

Filovirus genomes contain seven genes that code for different proteins, arranged in a conserved order.

Key filovirus proteins are Nucleocapsid (NP), RNA polymerase cofactor (VP35), Matrix (VP40), Envelope glycoproteins (GP), and RNA polymerase (L).

Ebolaviruses produce additional secreted glycoproteins (sGP).

Filovirus genes are arranged in a particular and conserved order, reflecting transcription.

Filovirus infections cause severe hemorrhagic fever, with symptoms like fever, hemorrhages, liver problems, and shock.

Filovirus spread among humans mainly involves close contact

Filovirus replication occurs in the cytoplasm, similar to other negative-sense RNA viruses like Paramyxoviruses.

The template for creating mRNA in filoviruses is the negative-sense RNA genome.

The 3' leader sequence of the filovirus genome contains a promoter for viral RNA polymerase and a packaging signal.

Viral RNA polymerase starts transcription at the 3' terminal of the filovirus genome.

Low levels of NP protein trigger a short mRNA sequence transcription followed by termination and mRNA re-initiation.

Protein L adds a methylated 5' cap and polyA tail to newly transcribed filovirus mRNAs, similar to cellular mRNAs.

A range of viral proteins (VP35, VP40, GP/sGP, VP30, VP24) are transcribed during different phases of infection.

When NP protein is unavailable, RNA polymerase transcribes a shorter region following sequence termination.

Process where viral RNA polymerase adds extra 'A' residues, altering protein sequence, creating GP, ssGP, or sGP variants.

RNA polymerase adding extra 'A' residue(s) during transcription.

Different forms of the glycoprotein (GP) produced by RNA editing, including full-length GP, shorter ssGP, and sGP.

Viral glycoprotein essential for attachment and entry of filoviruses into host cells.

An initial form of the GP protein, containing an N-terminal signal sequence which is removed.

process of attaching sugar molecules to Filovirus GP protein.

Process of cutting the GP precursor protein into GP1 (ectodomain) and GP2 (transmembrane) by furin.

Cells surface proteins that filoviruses attach to for entry.

Recombinant viruses designed to study filovirus proteins that incorporate the studied protein of interest, such as GP, into their envelope.

The process of a filovirus entering into a host cell, often involving fusion of the viral and cellular membranes.

The fusion peptide located at the N-terminal of GP2 enables filoviruses to fuse with the vesicle membrane after entering the cell via macropinocytosis. This fusion allows the virus to release its genetic material inside the cell.

Filovirus fusion with the vesicle membrane, which releases the viral contents into the cell, is likely triggered by a low pH environment inside the vesicle.

Although typically considered non-structural, sGP can act as a structural protein by forming a complex with GP2. This complex may play a role in efficient viral replication and infectivity.

Some studies suggest that sGP might limit the cytotoxicity of the GP protein. This could lead to more efficient replication and infectivity of the virus.

sGP can bind to antibodies, potentially interfering with the immune response and allowing the virus to evade detection by the immune system.

Since sGP is released from infected cells and can be found in the blood of patients, it's a potential target for vaccines and antiviral therapies.

Filoviruses have specialized proteins. Red proteins are associated with the viral genome and its packaging, while blue proteins are associated with the viral envelope.

VP30 is a viral protein in Ebolavirus that activates mRNA synthesis by reversing the inhibition caused by a stem-loop structure at the beginning of the NP gene.

The stem-loop structure in the NP gene acts as a "brake" on mRNA synthesis, preventing RNA polymerase from initiating transcription.

VP40 is the most abundant viral protein in Ebolavirus and is crucial for forming the viral envelope.

VP40 is found at the cytoplasmic side of the plasma membrane and the inner side of the viral envelope.

When expressed in mammalian cells, VP40 can create virus-like particles that bud from the plasma membrane.

VP40 interacts with cellular proteins involved in vesicle trafficking and sorting, helping to form virions at the plasma membrane.

In survivors of Ebola virus infection, periodic spikes in antibodies suggest a latent infection, where the virus persists and could reactivate.

Recrudescence refers to the recurrence of disease or symptoms after a period of inactivity, which can happen in Ebolavirus survivors.

Influenza viruses are relatively small, ranging in diameter from 80 to 120 nanometers.

Influenza viruses have a compact helical nucleocapsid, which contains their genetic material (RNA).

Hemagglutinin (HA) and neuraminidase (NA) are surface glycoproteins on influenza viruses. They play a crucial role in the virus's ability to attach to and infect host cells.

Influenza viruses are classified into three types: A, B, and C. Multiple subtypes within each type are distinguished by variations in HA and NA.

Avian influenza viruses can be highly pathogenic or low pathogenic. Some strains can infect humans, posing a serious threat to public health.

Common influenza symptoms include high fever, sore throat, cough, headache, and muscular pain.

Influenza viruses are primarily spread through respiratory droplets released when an infected person coughs or sneezes.

Influenza can be particularly dangerous for the elderly, infants, and people with chronic illnesses. It can lead to serious complications, even death.