Final; Retroviruses, AIDS, and Tumor Viruses Flashcards
Who are the members of the 4H risk group for HIV/AIDS
homosexual men
heroine addicts
Haitians
hemophiliacs
How many types of HIV are there
HIV-1
HIV-2
Where does HIV seem to originate from
the simian virus from Africa
Which type of HIV is mostly a heterosexual disease
HIV-2
This a large and diverse group of viruses with a unique replication cycle
retroviruses
In which genre of animals are retroviruses ubiquitous, albeit benign and causing little to no impact
vertebrates
This retrovirus does not cause disease in humans but makes foamy structures inside the cell
spumaviruses
What are the two subfamilies of retroviridae
orthoretroviridae
spumaviridae
What is the genome of the retroviridae
+ssRNA, diploid identical copies
What is the virion of the retroviridae
enveloped
What special proteins do the retroviridae contain
reverse transcriptase
integrase
protease
What were retroviruses historically characterized by
nucleocapsid structure and location of the particle
What are retroviruses now characterized by
genome contents; either simple or complex
What are the genes that simple retroviruses encode
gag, pro, pol, and env genes
What is the replication cycle of retroviruses
attachment entry reverse transcription integration transcription translation assembly release matuation
This converts viral ssRNA to dsDNA
reverse transcriptase
This puts the viral dsDNA into the host genome making a provirus
integrase (integration)
This is the defining feature of a retrovirus
reverse transcription
Reverse transcription initiates when
once the nucleocapsid is in the cytoplasm
needs higher levels of NTPs (nucleoside triphosphate)
Where does reverse transcription occur
within a large complex similar to the nucleocapsid
Reverse transcription is this between genome copies
promiscuous
many different recombinations when different genomes are in the virion
What must take place in order for integration to occur
it must have access to the nucleus during mitosis
although it can also infect non-dividing cell via importation (mechanism unknown)
How is the viral genome integrated into the host genome
3’ end processing of dsDNA
attack target DNA, nick created
host repair
True or False
Integration is permanent, there is no mechanism to remove it
True
If integrated into the germ-line, then provirus is inherited and is called what
endogenous
Which type of integration is identified as oncogenes
transcription factor
secreted growth factors
growth factor receptors
cell signal transduction pathway
True or False
There are many defective viruses made during replication
True
What constitutes a defective virus
missing at least one of gag, pol, or env
In order to make progeny of a defective virus, what must happen
a complementary infection with a virus that is not missing the defective gene
Many retrovirus infections are what
benign and usually not cytopathic with little impact to cell replication and physiology
Chronic infections of retroviruses cause what
they exert a small demand on cell and host resources but do cause viremia (virus in blood) and elicit an immune response
True or False
Viruses are never eliminated by the host response
True
In this type of retrovirus, the effect is like high-level mutagenesis and eventually results in tumoriogenesis
slow retrovirus
In this type of retrovirus, the majority carry cytopathic genes and directly cause tissue damage
cytopathic retrovirus
In this type of retrovirus, it induces rapid tumor formation, caries host genes (mitogenic or antiapoptotic) and is often replication defective because host gene replaces an essential gene
acute transforming viruses
What are the four distance types of Human T Cell Leukemia virus (HTLV)
1, 2, 3, and 4
HTLV-1 associated with humans
What type of retrovirus is HTLV-1
deltaretrovirus
How is HTLV-1 transmitted
person to person;
breastfeeding
sharing needles
sexual transmission (less efficient)
How is HTLV-1 transmitted within the host
highly cell associated
primary contact between infected and naive cells
What diseases can result from HTLV-1
adult T cell lymphoma/leukemia (ATLL); occurs in 2-4% of cases
HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP); occurs in 1-2% of cases
How long is the incubation of ATLL
30-50 years
What cells does ATLL infect (HTLV-1)
memory T cells
antigen activators trigger transcription of provirus, viral tax protein stimulates cell proliferation, the cell transform forming tumors with out without viral protein expression
How are ATLL and HAM/TSP transmitted
ATLL; mucosal infection
HAM/TSP; transfusion
What cells does HAM/TSP infect
infected T cells enter the CNS
activating astrocytes and microglial cells
recruiting inflammatory cells which cause further damage
What are the symptoms of HAM/TSP
onset 3 years after infection
starts with bladder control issues
progressing to lower back pain, leg weakness, or stiffness in hips/knees
men will suffer impotence or erectile dysfunction
What is used to prevent HTLV-1
eliminate breastfeeding for positive people
increased screening for blood products
What is used to treat ATLL
treat the lymphoma/leukemia with chemo
What is used to treat HAM/TSP
corticosteriods
interferon yields temporary relief of symptoms
What family is HIV apart of
lentivirus
two types of HIV, 1 and 2
How was HIV identified
due to immune deficiencies occurring in previously healthy young gay men
Where is the highest prevalence of HIV
in sub-sarahan Africa
How is HIV transmitted
sexual transmission; male to male is highest
parenteral; transfusion, needle sharing
mother to infant
What is the latent period of HIV
6 months to 25 years
In what part of the body does the HIV infection start
infection begins virus containing blood/body fluid to mucosal membrane
targets CD4+ cells
initial acute infection usually 2 weeks after exposure
What are the symptoms indicative of an HIV infection
mucocutaenous ulceration and weight loss
GALT seeded as a result of acute infection (reservoir)
What happens as HIV established a chronic infection
ongoing viral replication and T cell depletion
What results as a chronic HIV infection
opportunistic infections increase
wasting
What are the prevention strategies regarding HIV
sexual behavior and protection
blood screening
What are the treatments for HIV
no vaccine
antivirals; AZT is a reverse transcriptase inhibitor
