Retroviruses

TRUE or FALSE

Retroviruses are non-enveloped

FALSE

Retroviruses use _____ for DNA production

reverse transcription

TRUE or FALSE

Retroviruses are opportunistic

FALSE

What are the three human retroviruses?

HIV, HTLV, and human foamy virus

The first retrovirus (Rous sarcoma virus) was isolated by Peyton Rous in 1911. It produces?

Solid tumor in chicken

Classification of Retroviruses

The virion of retroviruses contain?

10-50 reverse transcriptase and integrase; 2 transfer RNA

What is the shape of retrovirus capsid?

Conical

Retroviruses have _____ genome

two single stranded (+) sense RNA

What gene encodes capsid, matrix and nuclear acid-binding proteins?

Gag

What gene encodes polymerase, protease and integrase?

Pol

What gene encodes envelope and glycoproteins?

Env

What contains promoter and enhancer?

Long terminal repeat (LTR)

Why is the retroviral genome non-infectious?

It does not encode a polymerase that can generate more mRNA

In addition to Gag, Pol, and Env, HIV-1 encodes six small accessory proteins. These are?

Tat, Rev, Nef, Vif, Vpr and Vpu

What method do retrovirus use to enter the host cell?

Fusion

How do retroviral virions exit the host cell?

Budding

Viral RNA is synthesized by _____ using the integrated provirus as template

cellular RNA polymerase II

What cells do HIV infect?

T-helper lymphocytes and macrophages

What co-receptor of T-helper lymphocytes is affected by HIV?

CXCr4

What co-receptor of macrophages is affected by HIV?

CCr5

What primary receptor is affected by HIV?

CD4

What produces DNA copy using viral RNA as a template and degrades original viral RNA?

RNA dependent DNA polymerase (reverse transcriptase)

What acts as a primer for reverse transcriptase?

tRNA

Reverse transcriptase lacks ____ thus it is very error prone

proofreading

LTRs of viral cDNA target specific sequences/structures in host genomic DNA (Chromosome) and integrate using HIV-1 _____

integrase

Viral cDNA is integrated into host DNA to produce ______

proviral DNA

TRUE or FALSE

Transcription of proviral DNA is mediated by viral RNA polymerase II (Pol II)

FALSE

Answer: host

TRUE or FALSE

Once the provirus is established, the DNA is permanently incorporated into the genome of the infected cell

TRUE

What are the cycles of HIV-1 infection?

Active and latent

TRUE or FALSE

HIV-1 infection cycles are reversible

TRUE

The early phase is driven by _____ enzymes performing abnormal events such as reverse transcription and DNA integration.

viral

Late phase is mediated by _____ enzymes performing normal processes (transcription and translation).

host

Retroviruses do not integrate randomly, they integrate into the _____

hot spots

What enzyme is used for reverse transcription?

Viral reverse transcriptase

What enzyme is used for transcription?

Host cell polymerase II

What are the singly spliced mRNAs?

Vif, Vpr, Vpu, and Env

What are the multiply spliced mRNAs?

Tat, Rev, and Nef

Which of these are spliced?

Gag, Pol, and Env

Env

What cleaves Gag to matrix protein (MA), capsid protein (CA), and nuclear capsid protein (NC)?

Aspartyl protease

TRUE or FALSE

HIV protease is a dimer

TRUE

HIV is derived from?

SIV

What are two HIV subtypes?

HIV-1 and HIV-2

TRUE or FALSE

HIV-1 infection is an epidemic

FALSE

Answer: pandemic

Who are disproportionately affected by HIV-1?

African Americans and Hispanics

How is HIV transmitted?

Blood, injection, sexual, and perinatal

What is the most common method of HIV transmission?

Sex

What had the highest new HIV diagnoses?

Male-to-male sexual contact

HIV express tropism. What cells are infected?

CD4-expressing T cells, macrophages, and dendritic cells

What symptoms occurs one to six weeks after infection?

Short, flu-like illness

TRUE or FALSE

Short, flu-like illness occurs one to six weeks after infection. However, the infected person can infect other people

TRUE

What stage of HIV can occur up to ten years (no symptoms, may be swollen glands, HIV level in circulation is very low, HIV antibodies are detectable)?

Asymptomatic

What stage has symptoms are mild (the immune system deteriorates, emergence of opportunistic infections and cancers, reduction of CD4 T cells less than 200/ml, increase viral load)?

Symptomatic

What stage shows the immune system weakens and the illnesses become more severe?

AIDS

What are the different ways in which AIDS may be manifested?

Lymphadenopathy and fever, opportunistic infection, malignancies, dementia

Reductions of CD4 T cells result from?

HIV-induced cytolysis, cytotoxic T-cells induced cytolysis, and chronic immune system activation

Infections commonly associated with AIDS

What was the highlighted opportunistic infection?

Oral candidiasis

How is it that HIV-1 evade the immune responses?

Decline of CD4 T cells, inadequate CTL response, existence of reservoirs, mutational potential

What is the standard test for HIV?

ELISA

TRUE or FALSE

ART is the effective cure for HIV

FALSE

What can significantly reduce viral load and dramatically prolong the lives of HIV-Infected people?

Antiretroviral therapy (ART)

What is the use of antiretroviral drugs after a single high-risk event to stop HIV seroconversion?

Post-exposure prophylaxis (PEP)

PEP must be started as soon as possible to be effective—and always within ______ of a possible exposure

72 hours

PrEP

Pre-exposure prophylaxis

What are associated with the group of people that are exposed to HIV but not infected?

CCr5 mutation and effective CTLs

What are used between each patient to prevent the transmission of HIV?

Universal precautions

What retroviruses are involved in actively spreading epidemics?

HTLV1 and HTLV2

HTLV-1 is prevalent in?

Japan, Africa, the Caribbean Islands, and South America (endemic)

What mode of transmission is breastfeeding?

Vertical transmission

What mode of transmission is sexual intercourse?

Transverse transmission

TRUE or FALSE

HTLV-1 is nonlytic

TRUE

HTLV1 can lead to the development of?

Neurological disease