Paramyxoviridae Flashcards
Henipavirus genus
However, of concern are paramyxoviruses in the Henipavirus genus whose natural host is the fruit bat but are highly infectious for swine and humans
Most of the paramyxoviridae have ______ and this is why we do not worry about them.
Vaccines.
Bovine Parainfluenza virus 3
host: cattle, sheep, other mammals
causes: respiratory disease in cattle and sheep
- Parainfluenza virus-3 is extremely widespread in cattle and 80-90% have antibody
- Isolatesvaryinvirulence
- Cessation of ciliary beating and epithelial necrosis predispose to secondary bacterial infections and coughing.
Peste de petits rumiants virus
Host: sheep and goats
Disease: severe generalized disease like rinderpest
Trying to get eradicated in the world
Rinderpest has been eradicated
PPR is a disease listed in the OIE Terrestrial Animal Health Code, and countries are obligated to report the disease Occurrence: North Africa to Tanzania, and in nearly all Middle Eastern countries up to Turkey-
Bovine respiratory syncytial virus
host: cattle, sheep, goats
Disease: respiratory disease
There are several other members of the Paramyxoviridae that are still waiting classification to existing genera
- Paramyxvovirus of reptiles
- Salem virus of equine
- Viruses of peguins
- Atlantic Salmon paramyxoviruses
turkey rhinotracheitis virus
in turkeys and chickens
severe respiratory disease in turkeys, swollen head syndrome of chickens
Virion properties
• Virions are P L E O M O R P H I C – spherical or filamentous (similar to Ebola)
- 150-350 nm in diameter
- Enveloped with large glycoprotein spikes (8-14 nm)
- Contain a “herringbone shaped” nucleocapsid- characterisitic
• The genome consist of linear, negative sense, single stranded RNA (13-19 kb in size)
- There is no 5’ cap or 3’ polyadenylation
- However, there are non-coding regions at both 5’ and 3’
Number of genes in respective genera
• The Respirovirus, Avulavirus, Henipavirus and Morbilivirus genera have 6 genes each
The Rubulaviruses have 7 genes
The Pneumoviruses have 10 genes
The Metapneumoviruses have 8 genes
The genome of the Paramyxovirinae encode at least 9-12 proteins
• The Pneumovirinae encode only 8-10 proteins
L gene encodes
Transcriptase for replication
Most of the gene products are found
Most of the gene products are found within the lipid envelope or complexed with the virion RNA
Virion structure
• Lipid bilayer
Virion structure
• 3 nucleocapsid proteins referred to as RiboNucleoProteins (RNP)
- RNA-binding protein (N)
- Phosphoprotein (P)
- Large polymerase (L)
3 membrane proteins:
- Unglycosylated matrix protein (M)
- Two glycosylated envelope proteins
————-Fusion protein (F)
————-Attachment protein hemagglutinin (H)
attachment proteins
A hemagglutinin-neuraminidase (HN) OR glycoprotein (G) - attachment proteins
Variably conserved proteins include
Variably conserved proteins include non-structural proteins (C, NS1 and NS2), cystein rich protein V, small integral membrane (SH), transcription factors M2-1 and M2-2
The envelope spikes of Paramyxoviridae are composed of 2
The envelope spikes of Paramyxoviridae are composed of 2 glycoproteins F and G or F and HN or F and H
The spike glycoproteins play an important role in
The spike glycoproteins play an important role in the pathogenesis of paramyxovirus
(HN, H or G)
One glycoprotein (HN, H or G) is responsible for attachment
F protein
F protein mediates fusion of the viral envelope with the cell membrane
neutralizing antibodies
The antibodies directed against the these proteins are usually neutralizing antibodies – important in protection against paramyxovirus infection
help with vaccine development
Where do paramyxoviruses replicate?
Paramyxoviruses replicate in the cytoplasm of infected cells
Pneumovirus do not encoded
Hemagglutaination, which makes it harder to find
What is interesting about replication?
Replication can also take place in the presence of a_ctinomycin D(cancer drug) or in enucleated cells_ – THUS, no nuclear function is required for replication
How does replication begin?
HN, H, or G attaches to compatible ligands (receptors) on the target
cells
This is different for each type of virus
Where is the replication receptor for Rubulaviruses, Respiroviruses and Avulaviruses ?
For Rubulaviruses, Respiroviruses and Avulaviruses the HN molecule binds to sialic acid residue – either glycolipids or glycoproteins
For Morbilliviruses, where is the receptor located for replication?
For Morbiliviruses, the receptor is located on lymphocytes, dendritic cells or macrophages – CD150
For Heniparviruses, where is the receptor for replication?
Fro Henipaviruses, the receptor is ephrin B2 and B3 cell surface proteins on endothelial cells or on brain stem neurons
For pneumonviruses, where is the receptor for replication?
For Pneumoviruses, the receptor is heparan sulfate(common for most viruses
After the attachement to the receptor what happens?
The F protein mediates fusion of the viral envelope lipid membrane with the target cell membrane
RNA-dependent RNA polymerase
The RNA-dependent RNA polymerase complex (transcriptase L) initiates RNA synthesis at a single site on the 3’ end of the genomic RNA
Replication of paramyxoviruses leads to
Replication of paramyxoviruses leads to lysis of infected cells or formation of syncytia
Paramyxoviruses produce
Paramyxoviruses produce inclusion bodies – cytoplasmic acidophilic, composed of ribonucleoprotein structures
Morbiliviruses produce
Morbiliviruses produce acidophilic intranuclear inclusion bodies composed of nuclear elements and protein N
What is a distinctive feature of Paramyxoviruses?
Hemoadsorption is a distinctive feature of Paramyxoviruses that express the H or HN proteine
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