ssDNA Viruses Flashcards
What is the typical ssDNA virus studied in class?
Parvoviridae
Describe the replication of Parvovirus
Attachment and endocytosis
Permeabilizes endosome to enter cytoplasm
MTOC to nucleus & penetration
ssDNA –> dsDNA
dsDNA transcription = mRNA in S phase
Rolling hairpin mechanism w NS1 endonuclease binding w 5’ end
ssDNA genomes taken from replication via junction resolution and encasidated to form virions released by cell lysis
How is canine parvo spread?
Fecal routes - highly contagious and hard to disinfect
Describe parvo symptoms
intestinal or cardiac which is lethal in 91% of untreated cases
Describe the ends of the parvo viral genome.
The ends of the ssDNA have complementary sequences which allow hairpin formation.
What purpose do the hairpin structures serve in the parvo genome?
They serve as primers for cellular DNA polymerase
In what form must DNA reside in order for it to be transcribed?
double stranded
Describe the rolling hairpin replication strategy.
ssDNA has terminal hairpin structures
3’ hairpin is primer for host enzymes to convert ssRNA into dsDNA
Initiated by viral endonuclease NS1 which nicks DNA between hairpin and coding sequences
New 3’ primers strand displacement replication and starts replication
When does parvo replicate in the host cells?
During the host cell’s S phase
How can parvo be stopped by the host cell during replication?
PML bodies in the nucleus
Where are PML bodies located and what are their purpose?
They are located in the nucleus and are used to inhibit viral replication by surrounding the viral machinery and inducing IFN
What does PML body stand for?
Promyelocytic leukemia protein
How does the parvo genome create a variety of proteins using a very small genome?
Alternative splicing
Describe alternative splicing.
It is a way for multiple RNAs and proteins to be generated from a single open reading frame. it is regulated by trans-acting proteins and regulatory sites on mRNA.
What is the principle of the rapid test kit?
Liquid will be placed on the sample pad on one side of the test which has antibodies. The control line will react with the antibodies regardless but the test qualitative line will only react with the reactive antigens that belong to the disease in question so will only show up if they are present.
