Sexually transmitted viral infections and HIV

What are 3 viruses that cause STIs (sexually transmitted infections)?

HIV, herpes, HPV (human papilloma virus)

What was the first appearance of AIDs in the country?

5 healthy gay men presenting with a rare fungal penruomia, pneumocystis pneumonia

Who is credited with dicovering the HIV virus?

Luc Montagnier (first to isolate the virus and detect the enzyme reverse transcriptase) AND Robert Gallo (connected the virus to the disease)

Where is HIV thought to originate from?

a similar virus, Simian Immunodeficiency Virus (SIV, that infects non-human primate

Why did the U.S. government ignore the AIDs virus for so long?

to was considered a disease of homosexuals who were stigmatized at the time, resulting in HIV entering the blooddonation system and killing transfusion recipients

Can HIV be transmitted sexually and through breast milk?

yes

Who is highest at risk for HIV?

injection drug users and men who have sex with men

HIV is a retrovirus, what does this mean?

the RNA genome is copied into DNA by the enzyme reverse transcriptase

What cells does HIV infect?

CD4 lymphocytes, (T-helper cells), although it can infect several other cell types

How does HIV infect T-helper cells?

it attaches to the CD4 protein on the cell surface as well as a co-recptor prtoein (CXCR4 or CCR5) to enter the cell 

Why does HIV cause such devastating disease?

without T-helper cells, there is almost no adaptive immune response, since they are responsible for activating B-cells (plasma and memory cells), macrophages, T cytotixic cells

What are the main forms of HIV?

HIV-1  (predominant strain)

HIV-2

How does HIV-1 replicate in a CD4 (T-helper cell)?

What is AIDs caused by?

human immunodeficiency virus (HIV)

HIV structure

enveloped virus, derived from the host-cell membrane with viral glycoproteins (pg120 and pg41) inserted into the membrane as the virus leaves the host cell.

core virus compostion: P24 capsid protein and PPI 17 matrix protein, 2 copies of single-stranded RNA viral genomes, 3 enzymes, reverse transcriptase, protease, intagrase

How does HIV establish infection?

1) Attachment to host cell via interaction between gp120 on surface of virus and CD4 antigen receptor

• co-receptor in T-lympocytes: CXCR4

• co-receptor in CCR5: macrophage

2) viral envelope and host membrane fuse, resulting in viral entry

3) RNA is released into cytoplasm of host cell

4) reverse transcriptase makes DNA copy of viral RNA genome, that RNA becomes degarded

5) complimentary DNA strand is then added by the reverse transcriptase and the ends of the resulting double-stranded DNA segment are joined non-covalently, creating a circular DNA

6) circular DNA is relocated to the nucleus and inserted into the host cell chromosome by the viral integrase enzyme.

• the integrated viral DNA is now called proviral DNA

7) proviral DNA may remain dormant or, with host cell activation, begin to transcript mRNA, yielding viral enzymes and structural proteins

How are some of the functional proteins formed via the HIV virus?

cleavage of a long polyprotein by the enzyme protease, protease, protease inhibitor interfere with this

How does the HIV-1 escape the immune system?

genome is integrated into the host chromosome

infected cells fuse, spreading the virus (escaping antibodies)

the adaptive immune system is compromised

infected T helper cells are located in protected areas of the lymp nodes

Can some peopl be asymptomatic before clinical latency?

yes

What is acute retroviral syndrome?

symptoms similar to flu, viral titer becomes very high and HIV infection spread throughout body

What occurs during clinical latency?

patient has no symptoms but the virus replicates, slowly destroying the patients CD4 cells

How does the HIV virus become AIDS ?

once they become low enough a critical threshold, the patient developes opportunistic infections and malignant tumors

What does it mean for patients with a low set point?

less virus, and more time before teh develope AIDS

What finalizes an AIDs diagnoses?

the level of CD4 positive T-cells in the blood drops below 200 cells per microliter

(a health person has 5X as many ~ 1000 cells per microliters)

What are defining AIDs conditions?

usually only present in severely immunocompromised patients

Candidasis, coccidiodomyosis, cryptosporidiosis, Histroplasmosis

Why would an AIDs pt be more likely to develope cancer?

reverse transcriptase makes many a mistakes; increasing the chance for mutations

Why do HIV-positive patients take a drug cocktail?

entry inhibitors, reverse transcriptase inhibitors, protease inhibitors, inegrase inhibitors “cocktail” called HAART

What contact has the small rate of transmission; oral, anal, or vaginal?

oral

What aids in the prevention of HIV?

condoms, syringe services programs or needle exchanges to prevent the reuse of needles, pre-exposure, post-exposure prophylactic drug combination(for people who regularly come into contact with HIV individuals)

What is P-R-E-P for pre-exposure prophylaxis?

consists of 2 drugs

How many people currently live with HIv/AIDs?

36.9 million people, 1.8 of them being childern

What are Lysis?

used in diagnostic testing, including at-home drug and pregnancy testing

What does the at home test for HIV test for?

detection of anti-HIV antibody

What are other common STIs?

genital herps

What virus causes genital herpes?

HSV-2

What virus causes oral herps/cold sores?

HSV-1

Is there a cure for genital / oral herpes?

Nope, but some antiviral medications can relieve some symptoms and reduce incidence of recurrences

Do condoms offer protection against gential/oral herpes?

Yes, but not full protection since many of the blisters are located outside the area of the condom.

What are the consequences for an infant with herpes?

infants born from women with a primary/first infection may die or duffer permanent disability; if herpes is detected in the mother, a C-section may be recommended

Human papilloma Virus (HPV)

common STI, at least 40 different types assocaited with cancers of the cervix, penis, vagina, rectum, and throat

many transmissable asymptomatic infections 

no cure since virus remains in the surrounding tissue

condoms offer some, but not full protection

most infections can be prevented with an effective vaccine

How can cervical cancer be prevented?

via vaccination and pap smears

What mutates faster than bacteria, especially RNA viruses?

viruses

What inhbits viral enzymes required for replication?

antiviral drugs