Lecture 6 Flashcards
What are 5 shared properties of all herpesviruses?
- spherical enveloped virions, 120-200nm in diameter
- icosahedral capsid, can have glycoproteins forming spikes
- linear double stranded DNA genome
- 100-240 kbp
- 70-200 genes
Where do all herpesviruses replicate?
replicate in the nucleuc with sequential transcription of immediate early a, early B, and late genes (y)
What are a (alpha) proteins for herpesviruses?
- include DNA binding proteins important for the regulation of virus gene expression
- some proteins involved in immune invasion fall into this kinetic class
What is meant by “kinetic class”
s a grouping of genes in a viral genome that are expressed at the same time during the viral replication cycle.
What are the B (beta) proteins for herpesviruses?
include enzymes involved in nucleotide metabolism as well as those required for genomic DNA replication
what are the Y proteins for herpesviruses?
consist mainly of structural proteins produced after the initiation of virus genome replication
True or False: herpes viruses can cause lifelong infections
true
what type of productive infection occurs for herpesviruses in permissive cells?
cytocidal
True or False: intranuclear infections, sometimes cytomegalic cells, or syncytia formation is never observed in herpesviruses?
false, it can be observed
What type of infections do herpesviruses establish?
latent infections
what are latent infections?
- the virus genome persists in the nucleus of specialized cells, but only a small subset of genes is expressed during latency
- think of this as “dormant” not active
- it is present, but does not cause the symptoms we would see that are associated with the disease until activated
- because of this it can “evade” detection, and be harder to treat because of it
What does reactivation for latency period trigger?
replication and shedding of infectious virus, leading to the symptoms seen with the disease
do herpes particles survive well outside the body?
no, they are fragile and don’t survive well outside of the body
How does transmission occur for herpesviruses?
transmission requires close contact, typically intimate contact that brings mucosal surfaces in direct contact
In crowded environments where animals are closely confined how does the herpesvirus quickly transmit?
sneezing, which causes short distance droplet spread, leading to transmission
What is alphaherpesvirinae?
- one of the subfamilies of herpesviruses
- grows rapdily and lyses infected cells
- establish latent infections in neurons of the peripheral nervous system
- some, but not all, have a broad host range (ex. HSV can infect a wide variety of species, whereas VZV infection is restricted to humans)
What are the human alphaherpesviruses?
HSV-1, HSV-2, VZV
What is betaherpesvirinae?
- one of the subfamilies of herpesviruses
- restructed host range
- grows very slowly (80-120 hours)
- cell lysis does not occur until several days after infection
- latency established primarily in monocytes and lymphocytes
- activation and replication of the virus in the kidney and secretory glands promote its secretion in urine and other bodily secretions, including semen and milk
what are gammaherpesvirinae?
- a subfamily of herpesvirus
- narrow host range
- establishes latency in and is capable of transforming B lymphocytes
- other gammaherpesviruses are also capable of causing cancer
How many herpesviruses are there for which humans are the natural host?
nine
how many proteins can the herpesviruses that humans are the natural host encode?
70-200 proteins
Can herpesviruses occur simulataneously?
yes, many can be infected with four+
What is “B Virus”?
- this is a tenth herpesvirus that can infect humans
- it is a type of alphaherpesvirus
- it is a monkey virus that causes a disease similar to HSV in macaques, however it is extremely pathogenic fo humans
- mortality rate is 80%
- causes acute CNS disease
What are poxviruses?
large viruses with DNA genomes that replicate in the cytoplasm of infected cells
