Hiv And Aids Test Questions – Flashcards
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What is a cancer vaccine?
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It is a treatment vaccine that introduces tumor antigens into the body to initiate the immune system to attack the tumor
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How do cancer vaccines that *treat* cancer work?
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--identify important or relevant tumor antigens --extract tumor to produce and multiply antigens in lab or synthesize antigens --introduce target antigens to body --immune system activates tumor-killing cytotoxic cells --exploits immune system's own ability to produce T cell attack on tumor
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What adoptive T cell therapy helped cure Emily Whitehead?
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CAR T-cell therapy
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How did Emily's therapy work?
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--T cells engineered in lab to recognize tumor antigen --engineered to not die --provides immune system w/more potent weapon (T cells kill B cells)
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What are tumor cell inhibitors?
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They suppress the action of the immune system, specifically cytotoxic T cells
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What are monoclonal antibodies?
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Cancer cells rely on proteins from nearby healthy cells to hide from the immune system, so monoclonal antibodies can be used to 'tag' cells and make them more visible to cell engulfing immune cells
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What is T-VEC?
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--vaccine for advanced melanoma --destroys malignant cells directly
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How does T-VEC work?
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It releases a specific protein and antigens that enable the immune system to target cancerous cells nearby and throughout the body
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What is an oncolytic virus?
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A virus that is cancer specific; highly responsive to activated oncogenes and tumor suppressor loss
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Significance of oncolytic virus?
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IF VIRUS BECOMES A TUMOR CELL: virus replicates, tumor cell ruptures and dies, and virus spreads and promotes immune response to distant tumor IF IT REMAINS A HEALTHY CELL: it does NOT support oncolytic virus growth, and so the virus dies and the healthy cell lives on
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What is the relationship between HIV and CD4+ cells?
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HIV preferentially targets and kills CD4+ immune system cells, specifically T-Helper cells
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What are CD4+ cells, and what do they do in the immune system?
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They help immune system cells talk to each other
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When did AIDS become evident to the medical community via the CDC's MMWR?
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1981
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When was the virus likely introduced into the US?
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1984
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When was the virus first introduced to humans through a cross species event?
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Around 1900 in West Africa from a Chimpanzee
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What does AIDS stand for?
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Acquired Immune Deficiency Syndrome
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What doe HIV stand for?
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Human Immunodeficiency Virus
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Which country's president denied that HIV infection causes AIDS?
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South Africa; caused 330,000 deaths
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What is HIV-1's origin?
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--recombined SIV form that thrived in chimps --has special attributes to allow it to be viable and thrive in humans
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What is so special about HIV-1?
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Most cross species events are rare and are rarely able to make new species so vulnerable
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What are some factors that have led to the establishment and spread of HIV across the globe, causing a worldwide epidemic?
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Travel, blood industry, injected drug use, unprotected sex, prejudice, and denial
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What genetic material makes up the virus particle of HIV?
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--nucleic acid (single or double-stranded DNA or RNA) --coat of protein that surrounds the DNA or RNA to protect it (*capsid*) --lipid membrane which surrounds the protein coat of some virions (*lipid bilayer "stolen" from host cell, called "enveloped" viruses*)
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What is significant about the lipid membrane, or envelope of the HIV virus?
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--"stolen" from host cell as virus particle buds out/emerges and becomes a mature virus --72 spikes that protrude from envelope made up of 2 different proteins (HIV Integrase and HIV Protease)
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What is HIV Integrase's function?
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It is responsible for integrating HIV DNA into host cell DNA, making it an attractive target for anti-HIV drugs
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What is HIV Protease (PR)'s function?
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It cleaves a polypeptide so that functional viral proteins can form
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What happens to HIV virions without active HIV PR?
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The virions remain noninfectious
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What viral enzymes/proteins have a role in the HIV lifecycle?
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*gp120* (involved with CD4 binding) and *gp41* (involved in coreceptor binding)
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What is Reverse transcriptase?
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a protein that allows HIV to break the rule stating that in the cell moves from DNA to RNA to protein...
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How is Reverse transcriptase involved in the lifecycle of HIV?
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--uses viral RNA to make complementary DNA --makes a second strand of DNA to make it ready for host
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What is syncytia?
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It causes the depletion of functioning immune cells
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What initiates syncytia?
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The infection of CD4 cells, as they eventually express gp120 on their surface *-->* host cells thus act like HIV and fuse w/another CD4 expresing host cell
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How does HIV kill host cells?
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HIV gradually destroys the immune system by attacking/killing CD4 cells, using CD4 machinery to reproduce itself and spread throughout the body
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How many stages are there in the progression from HIV to AIDS?
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4
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What are these stages?
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Stage 1: primary acute HIV infection, short flu-like illness, large amount of HIV in peripheral blood Stage 2: clinically asymptomatic, no major symptoms, lasts ~10 years, HIV level in peripheral blood drops to very low levels, patient remains infectious Stage 3: symptomatic HIV infection, immune system loses struggle to contain HIV, damaged lymph nodes and tissues, HIV mutates, emergence of opportunistic infections Stage 4: progression from HIV to AIDS, CD4+ count below 200, high set point/viral load
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What is a viral load?
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the amount of the HIV virus in the blood
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What is a set point in relation to HIV?
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It is the viral load at which antibodies have been produced and the body begins fighting off infection (during Stage 2)
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What is the worst case scenario for an HIV patient?
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CD4 count LOW, viral load HIGH
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Best scenario for HIV patient?
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CD4 count HIGH, viral load LOW
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What are Elite Controllers?
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--infected with HIV but immune system is able to maintain an undetectable viral load *without HAART* --represent less than 1% of people infected; innate immunity
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What set point do elite controllers have?
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Undetectable, under 50 copies/mL
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What is the relationship between viral load and rates of transmission?
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--timing during infection cycle --HAART to keep viral load down --co-occuring STIs can increase viral load and physical exposure --risk of transmission higher w/receptive sex than insertive --risk of transmission higher w/receptive anal sex than receptive vaginal sex
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What fluids can transmit HIV?
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Blood, semen, pre-seminal fluid, rectal fluids, vaginal fluids, and breast milk
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What does NOT transmit HIV?
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air, water, insects (mosquitoes/ticks), saliva, tears, sweat, casual contact, closed-mouth or "social" kissing, toilet seats, sharing musical instruments
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How long does HIV survive outside the body?
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Not long
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Can you get HIV by *donating* blood?
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No
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What is MTCT?
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Mother-to-child transmission
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Does CD4+ cell count affect how long infected mothers should receive ART?
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No, they should receive lifelong ART regardless of cell count
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What means of exposure lead/factors contribute to MTCT?
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trauma of birth, breast feeding, stigma
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What is the window period in an HIV infection?
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3-12 weeks (21-84 days); from infection until detection of antibodies against virus or viral RNA
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True/False: During the window period, HIV will likely *not* be detected?
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TRUE
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During the window period, a person may be infectious even though the screening test does not detect HIV. What is this called?
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False negative
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Relationship between PreP and window period?
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PreP can prolong the window period
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What is seroconversion?
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the time at which protein antibodies have increased to detectable levels in the blood
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When should you be tested for HIV?
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--had 3+ sexual partners in last 12 months --have received blood transfusion before 1985 --have sexual partner who received transfusion and later tested positive for HIV --not sure about partner's risky behavior --being male who has had sex w/another male --using street drugs by injection/shared needle --having an STD --being a healthcare worker w/direct exposure to blood on job --ASAP IF YOU THINK YOU HAVE BEEN EXPOSED
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What is the HIV rapid test?
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--most common HIV test: antibody screening test --tests for the antibodies that your body makes against HIV --produces quick results, in 30 minutes or less --uses blood or oral fluid to look for antibodies to HIV
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If a rapid test gives a positive result, what needs to be done to *confirm* it?
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Western Blot
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What is a Western Blot?
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--looks for specific HIV proteins in the blood --detecting antibodies to lots of specific proteins (antigens) at the same time
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What are the 2 major ways AIDS causes death?
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Wasting Syndrome and opportunistic infections
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What is Wasting Syndrome?
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weight loss of at least 10% in presence of diarrhea or chronic weakness and documented fever for at least 30 days that is not attributable to a concurrent condition other than HIV
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What is an opportunistic infection?
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an infection that occurs more frequently and is more severe in individuals with weakened immune systems, including people with HIV
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What do entry and fusion inhibitors do?
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FI blocks entry into the host cell
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What do Reverse Transcriptase inhibitors do?
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--interfere with reverse transcription, when HIV RNA is converted to HIV DNA --2 types: Integrase and Protease
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What do integrase inhibitors do?
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block the viral DNA from being inserted into the host cell genome
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What do protease inhibitors do?
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interfere with protease, the enzyme HIV uses to produce infectious viral particle by cleaving polypeptides --virus can't mature without polypeptides being cleaved --virus is then incapable of infecting a new cell
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What are the 2 types of reverse transcriptase inhibitors?
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NRTIs and NNRTIs
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What are NRTIs?
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faulty DNA building blocks --when these faulty pieces are incorporated into HIV DNA (during the process when HIV RNA is converted to DNA), the DNA chain can't be completed
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What are NNRTIs?
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bind to RT, interfering with its ability to convert HIV RNA into HIV DNA
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What is the problem with reverse transcriptase?
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It's a very sloppy protein, and it makes mistakes
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What is the significance of reverse transcriptase being sloppy?
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If it makes mistakes, then the mutation rate is very high for HIV
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Why do we almost always use a combination of ARVs?
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taking 2+ ARVs simultaneously vastly reduces the rate at which resistance develops
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What is HAART?
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Highly active antiretroviral therapy, used to describe a combination of 3+ anti-HIV drugs in a single pil
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What types of drugs are commonly used in the HAART combination?
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2 NRTIs with one NNRTI or PI
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Which protein in the HIV lifecycle is mostly responsible for the ease at which HIV gains resistance to specific drugs?
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--HIV relies on proteins, including gp41, to latch on to CD4 cells and infect them --mutations can occur in any of these parts of the virus and cause drug resistance
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What is Atripla?
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--tablet that contains 2 ARVs used to fight HIV --taken as one tablet, once a day --approved in 2006 as an ARV for adults w/HIV
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What is the 90-90-90 goal?
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By 2020: --90% of all people living w/HIV will know their HIV status --90% of all people diagnosed w/HIV will receive sustained ART --90% of all people receiving ART will have viral suppression
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What are some reasons why people don't get tested for HIV?
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--fear --$$$ --have to find/travel to a place to get tested --stigma --distrust in health care system --people assume they're not at risk --people think less about HIV/AIDS than they used to
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What subgroups of the American population carry a disproportionate burden of HIV?
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Blacks and Latinos
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How do we define a cure for HIV?
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--able to live a healthy lifespan without ART of HIV-related medication --incapable of transmitting virus to other people
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What are some reasons vaccines for HIV have been so difficult to produce?
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--HIV mutates: during first 10 days of infection, HIV may mutate more than all of the known strains of influenza have mutated in all of human history... --reservoir problem: HIV can be dormant in 'reservoirs,' hiding/sleeping in our cells --ART can sometimes kill all active HIV, but once treatment stops, HIV can reemerge when 'sleeping' HIV are reactivated --no drugs exist that can cure HIV/AIDS; drugs cost $$$, not always reliable, require faithful adherence to protocol, and cause side effects
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What protein is largely responsible for most of the frustration in creating an effective vaccine?
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PD-1
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What does PD-1 do?
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keeps our immune T cells from killing cancer cells
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What is a preventative vaccine?
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prevents infection in people who are HIV *negative*
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What are the problems with preventative vaccines?
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They fail in protecting from mutated forms of HIV
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What is the 'Kick and KIll' treatment proposal?
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ART is be used to make sure HIV is undetectable, so 2 vaccines would train the immune system to recognize cells that will be activated --Vorinostat used to wake sleeping cells --immune system, boosted by vaccine, attacks and kills newly activated cells
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What is the purpose of 'Kick and Kill'?
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--*therapeutic* vaccine that deals with the virus reservoir --keeps viral load LOW --vaccine first trains immune system to identify virus-producing cells --specific drug activates the virus in 'sleeping cells' --cells that are now producing virus are immediately recognized and killed
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What is the innate component of the immune system?
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it acts fast and is ready to respond to new threats to the body
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What is the adaptive component of the immune system?
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it is trained and takes longer to respond
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Which component of the immune system do T and B cells belong to?
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adaptive immune system
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What about macrophages?
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innate immune system
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What may result in an antigen expressed on the cell's plasma membrane?
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a mutation that alters a normal protein within a cancer cell
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What happens to the antigen if such a mutation were to occur?
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it would appear as non-self
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Does immunoediting aid or inhibit the immune system?
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Inhibits because it allows the cancer cells to escape attack by the immune system
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How are preventative vaccines and therapeutic cancer vaccines similar?
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they both introduce an antigen specific to tumor cells to the body to activate the immune system to attack cancer cells
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What is another name for Car T-cells?
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serial killer T cells
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What are serial killer T cells?
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they are cells engineered to identify and kill tumor cells repeatedly
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What are some explanations for the 1980 emergence of AIDS in the US?
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--hunter theory: strain from a chimp was introduced to hunter and virus was able to survive and infect human host --virus spread thru African urban center w/an active sex trade, reuse of needles among medical facilities, and active trade/travel --virus came to US via Caribbean as ppl moved from the Congo to Haiti to the US
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The HIV virus has genetic material in the form of _______
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single-stranded RNA
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Which protein specifically interacts with the CD4 receptor on the host CD4+ cell?
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GP120
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Which HIV protein allows viral and host cell lipid membranes to fuse?
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GP41
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How can HIV 'hide' in the body?
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by hanging out with its genome integrated in the host genome and the viral genome is not transcribed
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What happens when HIV-infected CD4 cells bind to uninfected CD4 cells?
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Masses of fused cells form
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What do infected CD4 cells eventually express?
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gp120
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True/False: syncytia always occurs right after infection
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FALSE
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What is Kaposi's sarcoma?
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--a rare type of cancer --began appearing on previously healthy young men without any clear explanation and accompanied unexplained infections that proved to be fatal in the beginning of the AIDS epidemic
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What factors affect the transmission of HIV by an infected individual?
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viral load, STI outbreaks, unprotected sex
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True/False: CD4+ cell count affects the transmission of HIV by an infected individual
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FALSE
