Retrovirus, Aids and tumor virus Flashcards
in 1970 Baltimore and Temin discovered what
reverse transcriptase
in 1981 Gallo and associates discovered HTLV 1 the first what
HTLV 1 the first retrovirus in humans
70 and 80s the ______ risk group begin dying of opportunistic infections defining a new disease of ____
the 4H club
AIDS
theory of HIV origin
HIV evolved from simian virus in Africa and spread through human mobility
theory SIV to HIV2 to HIV1
initial infection of HIV in humans seemed to occur when
1930ish
retrovirus quick facts
retroviruses large diverse group
unique replication cycle
many are benign causing little impact on host cell
others cause significant disease and cancer
two subfamilies of retrovirus
orthoretrovinnae
spumavirinae
what genus causes ASLV and RSv
alpharetrovirus
what genus causes MMTV
betaretrovirus
what genus causes MLV
gammaretrovirus
what genus causes HTLV1, HTLV 2, HTLV 5
deltaretrovirus
what genus causes HIV 1 and HIV 2
lentivirus
do spumaviruses causes disease in humans?
NO, they make foamy instructors inside of cells
retrovirus biology including family, genome, virion, replication location
family: retroviridae
genome: +ssRNA
virion: enveloped
REPLICATES IN NUCLEUS
where does retrovirus replicate
IN THE NUCLEUS AN EXCEPTION
is the genome of thE retrovirus diploid or haploid
diploid: identical copies
describe the proteins of retrovirus
reverse transcriptase- to go from RNA to DNA
integrase- inserts retrovirus into host genome DNA
protease
SP 120 and sp41 - proteins for attachment
what is the most common retrovirus nucleocapsid structure and location
D type cylindrical nucleus centrally located
what do simple retroviruses encode
The Gag, Pro, Pol, and Env genes
what do complex retroviruses encode
Gag, Pro, Pol, Env and other genes including rev, new, lt., tat
where does retrovirus replicate
nucleus!!
explain the retrovirus replication cycle
attachment, entry, reverse transciptase changes sRNA genome to dsDNA
the dsDNA is then integrated into host dan making a provirus
transcription occurs from provirus
translation occurs, assembly, release and then maturation which includes protease activity
retrovirus biology transcription description
uses reverse transcriptase to go from RNA to DNA. initiates once nucleocapsid is in cytoplasm needs high levels of NTPs
infection does NOT occur if reverse transcriptase can not occur
what prevents reverse transcriptase in retrovirus
low NTP levels
what has to occur for retrovirus infection to progress
reverse transcriptase has to occur for retrovirus infection to progress
when is reverse transcriptase silent
when copies between genomes are identical
how is retrovirus genomes integrated into host genome
through access of host nucleus, access during mitosis which means host cells must be dividing (but can infect non dividing cells through importation)
3 end processing of dsDNA
attack target DNA nick created
host repair - viral genome deficiencies can be fixed by host repair system
can retrovirus genome be corrected once integrated into host genome? if so how?
yes, host cells repair systems are used to fix the retrovirus genome
how can retrovirus infect non dividing cells? explain this concept
thru importation - mechanism is unknown
is integration of virus DNA permanent
YES
can retrovirus DNA be passed on to offspring
YES, provirus can be integrated in germ line and is called endogenous once this happens
can integration cause cancer
yes
name the integration identified oncogenes
transcription factors, secreted growth factors, growth factor receptors, cell signal transduction pathways
do retroviruses make defected viruses during replication? what other virus does this commonly
Yes, many defective viruses are made, missing at least one protein can carry oncogenic properties
Rabies often defective
What does a defective retrovirus require to make progeny
a complementary infection
quick facts about retrovirus and infections in humans
many are benign, usually not cytopathic, do cause viremia elicit a immune response but host can live normal lifes, virus is never eliminated
name 3 groups of retrovirus
slow retrovirus
cytopathic retrovirus
acute transforming viruses
describe slow retrovirus
Eg: leukemia
high level mutagenesis
results in tumors
cytopathic retroviruses
minority of retrovirus
cause tissue damage directly
acute transforming viruses
induce rapid tumor formation
carry host genes (mitogenic, antiapoptotic)
often replication defective bc host gene replace essential viral genes
Describe the biology of HTLV including family
four distinct types 1, 2, 3, 4
deltaretrovirus
first isolated in patient with cutaneous T cell lymphoma in late 70s millions affected worldwide
Describe HTLV transmission
person to person, drug users, blood, sex (less efficient) mother to child via breastfeeding
in host highly cell associated, primary spread through contact between infected and naive cells
