rock%lighthouse%pyrdc%wubios@uunet.UU.NET (Roger Rock Rosner) (10/28/89)
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EDUCATION/SERVICES - Table of Contents December 1988 - Vol 1, No 1
A Layman's Guide to HIV
"Shortcuts:" How to get a handicapped Metro flash pass
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A LAYMAN'S GUIDE TO HIV
AN EXPLICIT DISCUSSION OF HIV AND HIV TRANSMISSION FOLLOWS.
This is a (hopefully) simplified guide to understanding how the virus that
causes AIDS works.
First, you have a virus. The one we are concerned with is called Human
Immunodeficiency Virus, or HIV.[1] The name HIV helps distinguish it from
similar viruses that can cause analogous diseases in animals. For example,
there is a virus called SIV or Simian Immunodeficiency Virus that affects
African Green Monkeys and macaques and gives them "SAIDS," or Simian
Acquired Immunodeficiency Syndrome.
GETTING IT IN YOUR BLOOD
In order for HIV to affect YOU, it has to enter YOUR bloodstream. There are
eight basic routes of transmission that account for almost all (97%) of the
cases we know about to date:[2]
1. ANAL RECEPTIVE SEX WITH SOMEONE WHO IS INFECTED--The job of your
digestive system is to absorb nutrients from what you ingest and place
them in the bloodstream. Unfortunately, anything placed in the rectum
is also almost immediately absorbed and placed in the bloodstream (this
is how suppositories work). If you have anal sex with someone who is
infected, and they ejaculate in your ass, the virus which is contained
in their semen can enter your blood, and you can be infected. Of
course, anal sex is just as dangerous for heterosexuals is as it is for
homosexuals, since the physical route of transmission is the same.
2. SHARING HYPODERMIC NEEDLES DURING IV DRUG USE--If you use a hypodermic
needle that was previously used by someone who is infected with HIV,
some of their blood stays in the syringe (along with the HIV virus in
it), and when you then shoot up, their blood and HIV get directly
injected into your bloodstream.
3. VAGINAL/GENITAL SEX (for heterosexuals or bisexuals)--HIV infection can
occur during vaginal/genital sex and the infection can be passed in
either direction, from and to either partner. Sex between a woman and
a bisexual man is somewhat more risky for the woman than sex with a
heterosexual man, because bisexual men are more likely to be infected.
4. TRANSFUSIONS FROM A DONOR WHO IS INFECTED WITH HIV--Blood banks now
screen all donated blood to try to prevent this. However, many people
were infected before screening tests were developed, and even now,
approximately 80 units of blood out of 4 million donated each year will
slip through the screening process and have the potential to infect
recipients with HIV. Also, many hemophiliacs who are dependent on
blood products (a clotting factor called Factor VIII) for survival
became infected with HIV before the screening tests were developed.
5. FROM A MOTHER INFECTED WITH HIV TO AN INFANT--An infant can become
infected with HIV from its mother through three possible routes:
o in utero (in the womb) by passage of the virus through the
placenta
o during labor and delivery through exposure to infected blood and
vaginal secretions
o after birth through breast feeding with infected milk.
An HIV-infected mother will pass the infection along to her baby in 20
to 60 percent of all pregnancies. Current projections indicate that as
many as 4,000 babies will get HIV infection during 1988 alone.
6. ORAL/GENITAL SEX--HIV can be transmitted from an infected person to a
healthy person during oral/genital sex in which semen (cum) is
deposited in the mouth of the healthy partner. ALWAYS USE A CONDOM
DURING ORAL SEX!
7. ORAL/VAGINAL SEX (for lesbians)--Although lesbian oral sex is not a
likely route of transmission, it is a possible route (at least one case
of lesbian-to-lesbian transmission has been documented), and lesbians
should use shields during oral/vaginal sex. HIV can hide in your cells
for many years (as you will learn below), and one lesbian partner might
have been infected during previous heterosexual encounters, rape, or
IV-drug abuse.
8. Exposure to HIV-infected body fluids--For example,
o a nurse accidentally being stuck with a syringe after
administering an injection to someone who is HIV-infected (the so-
called "needlestick" injuries)
o a surgeon being stuck with the needle while stitching up an HIV-
infected patient (theoretically)
o blood from an AIDS patient coming into contact with an open wound
on the hands of a home-care worker (theoretically).
(These last two examples have never been documented to have actually
taken place.) The risk of HIV transmission from needlestick injuries
fortunately occurs at a very low rate. A higher risk is incurred by
researchers working with high concentrations of HIV, as is done in
vaccine work and other HIV research.
The methods of transmission above have been listed in order of probability.
Although there is theoretically a chance of getting HIV from deep kissing,
it has never been documented, and recent research may have discovered an
agent in saliva that kills HIV. [NOTE: THIS IS NOT AN EXCUSE FOR HAVING
UNPROTECTED ORAL SEX! The amount of HIV contained in saliva is very small,
and if your saliva can kill the HIV in their saliva, great. If you
overwhelm your mouth with HIV by sucking someone off, chances are very high
that you will swallow at least some of their semen before your saliva can do
a thing about it. BE SENSIBLE! USE A CONDOM EVERY TIME YOU HAVE ORAL SEX!]
Transmission of HIV through casual contact, mosquito bites, etc., has never
been proven. In addition, hundreds of families of AIDS patients have come
into close contact with them on a daily basis for long periods of time
without contracting HIV. If HIV could be spread through casual contact,
then it would be expected that other family members would be infected with
HIV from sharing the same glass, or brothers and sisters of children with
AIDS who are sharing the same toothbrush, bed, etc., but it just isn't
happening.
INSIDE YOUR BLOOD: THE BATTLE BEGINS
HIV destroys your T4 cells, which are essential for your immune system to
function, and this destruction of your immune system is what causes the
syndrome known as "AIDS." This is how HIV does it:
HIV is a retrovirus. This means that its genetic "blueprint" is composed of
RNA instead of DNA, which is the usual genetic material for viruses,
bacteria, and in fact all other known life forms. A virus cannot reproduce
itself. It has to attack a cell and steal many of the components needed for
reproduction in order to produce more of itself.
HIV is made up of strands of its own unique pattern of RNA, which is a
complex string of chemicals that form the blueprint or pattern for HIV to
build more of itself, surrounded by a coat of protein and by an outer
membrane layer also impregnated with proteins.
Once in your blood, HIV waits until it comes into contact with the infamous
"T4-helper" cells of your immune system. These cells help direct your body
to attack invading cells, fight off diseases, etc. When HIV encounters a T4
cell, it somehow (we don't know how) gets inside the T4 cell, sheds its
protein coat and injects its RNA strand and some other chemicals it needs
inside the cell. (Think of the "face-hugger" from "Alien," and you get the
idea.)
HIV then uses the raw material in the T4 cell to help it build a DNA copy of
its RNA strand. It does this by using a large protein (enzyme) called
"Reverse Transcriptase."
The RNA strand can be copied because the chemicals that make up the RNA
strand will only bond with certain complementary chemicals (just like only
magnets with opposite poles will stick together). So only the correct
"opposite" chemicals will bond with each part of the RNA strand.
After the whole RNA strand has a "mirror image" DNA counterpart, another
chemical is released which eats the RNA strand, and it breaks down. The
single DNA strand then gets copied again to form another "mirror image"
strand (which now looks exactly like the original RNA strand, but is more
stable). The HIV virus has now managed to infect a cell and create a copy
of itself that is more durable and is able to reproduce.
What happens at this point is unclear. The rest of the T4 cell still has
its original DNA that makes up its personality. In many instances, it
seems, the DNA copy of HIV manages to break the DNA of the T4 cell in half
and stick itself in the middle to hide. (Imagine a snake having a head at
each end that wanted to hide in a rope. It could just cut the rope, and
have each head bite one of the cut ends.)
This helps explain why HIV can stay dormant in your body for so long. When
the rest of your immune system takes a quick glance at the cell, it looks
like a normal T4 cell. The average dormant time for HIV is now thought to
be around eight years.
At some point, something activates the virus. We still don't know exactly
what. It is known that certain chemicals can activate it (which is why drug
therapies can be risky, and alcohol and other drugs are to be avoided), and
it has been proved conclusively[3] in the laboratory that without any other
help, Ultra-Violet (UV) light will definitely cause the virus to activate.
(In recent experiments, the equivalent of a 30-minute sun exposure caused
the virus to replicate 12 times faster.) This is why people who are HIV-
infected should not use sun parlors, tanning booths, etc., and should use a
strong sun-block when exposed to direct sunlight outdoors. Let's face it,
you are much more attractive pale and well, than tan and sick.
When HIV activates, it copies its DNA back into RNA, and then makes copies
of its RNA. It continues stealing what it needs from the host cell and then
moves over to the wall of the T4 cell and "buds" off--like a bubble coming
off a soap film, HIV just surrounds itself with cell wall until it is
completely surrounded and it finally floats off.
This may also help fool the body into not attacking it, since the rest of
the immune system just sees normal T4 cell wall floating on down the
bloodstream (the old "wolf-in-sheep's-clothing" trick). This new virus
floats along until it encounters a healthy T4 cell, which it then attacks,
and the cycle begins again.
There is also evidence that HIV infection can destroy T4 cells, causing them
to burst and release HIV throughout the bloodstream. Another nasty thing
that HIV can do is bind a large group of T4 cells into a big ugly blob
called "synctica," (like roping a bunch of barrels together to form a raft--
it floats, but the barrels in the middle are pretty useless to anyone in the
water). This combination of binding T4 cells into synctica and the bursting
of T4 cells helps explain why the number of T4 cells per cubic millimeter go
down as the virus gets more active. (The normal range for T4 cells is
approximately 600-1200 cells per cubic millimeter. The Centers for Disease
Control Surveillance Definition of AIDS[4] makes reference to a count of
less than 400 T4 cells/mm^3 as being indicative of AIDS; below 200 is
considered serious by most health professionals.)
Unfortunately, there is also evidence that HIV attacks brain cells too, and
that the immune system is not the only target. HIV is now known to infect
other cells in addition to T4 cells. These include macrophages and
monocytes, which are types of white blood cells involved with fighting
infections. HIV can "hide" in these cells, not increasing in number and
remaining inactive until some event or combination of events triggers it
into actively replicating.
HIV can also cause AIDS dementia. The exact mechanism of infection is not
completely understood, but somehow HIV crosses the barrier between blood and
the brain. Glial cells in the brain can be infected, and other factors may
be involved. AIDS dementia has been found to be reversible in some patients
following treatment with AZT.
THE NET RESULT
Every day, your body is bathed in germs. This plethora of bacteria,
protoplasms, and others are essential for your body to function. For
instance, you could not digest food without the bacteria in your stomach.
In the course of your daily life, you are exposed to thousands of attacking
organisms that want to infect you, and normally your immune system takes
care of smashing them down. (Think of lots of rebels and a government
dictatorship protected by the army). As soon as your immune system gets
impaired (your army dies), all the diseases which you have been carrying for
years can run amok (the rebels seize power). Think of how quickly a cold
can take hold when you're just run down (emotionally and/or physically),
even if you're otherwise healthy.
The unfortunate thing is that many of the so-called "opportunistic
infections" associated with AIDS (that is, infections that you basically
only get because your immune system isn't working) are things that your body
has had in it for years. Even if you wanted to pull the Howard Hughes
routine and go live in a sterile glass bubble somewhere, the germs you
already have in your body are probably more than sufficient to kill you.
While if you are HIV-infected you should not put yourself in an atmosphere
laden with germs, the other extreme of retreating to complete isolation to
try to live forever is a nice fantasy that won't work.
THE COUNTER-ATTACK: STRATEGIES & TACTICS
The most obvious thing to do if you aren't infected with HIV is don't get
infected. This basically comes down to one simple rule: DON'T LET SOMEONE
ELSE'S BODY FLUIDS GET IN CONTACT WITH YOUR BODY FLUIDS. The health
professionals are now saying anal sex is too risky, even with condoms,
because a condom failure (and they DO fail), for instance, a breakage,
slippage, or leak, could be disastrous. The link between anal receptive sex
and HIV infection is too overwhelming to be ignored. Oral sex with condoms
is PROBABLY okay (notice the word, probably). ANYTHING THAT INVOLVES
EXCHANGE OF BODY FLUIDS, I.E. SEMEN, BLOOD, URINE, FECES, ETC. IS OUT! And
although it probably seems obvious, it can't be said too often: USE A
CONDOM EVERY TIME! Using a condom some of the time is like playing Russian
Roulette and pointing the gun at the ground some of the time and your head
some of the time. Which chamber contains the bullet is not affected by
where you have the gun pointed when you press the trigger.
Once HIV is in your blood, the next line of defense is to kill or neutralize
the virus before it has an opportunity to attack and infect your T4 cells
and other target cells of HIV (such as monocytes and macrophages). Vaccines
work by getting your body prepared to fight an infection before it happens.
When vaccinated, your body responds by flooding your blood with antibodies
that are on the lookout for HIV. When the antibodies see HIV, they attack
it, bind to it, and render it ineffective, thus preventing HIV from causing
damage to your immune system and from replicating.
The next stage of attack is to stop HIV from being able to bind to your T4
cells. One experimental treatment, AL-721, is a "food" that is made from
derivatives of egg yolks. It is believed that AL-721 somehow alters the
strength of the wall of the T4 cell so that HIV cannot penetrate it (sort of
like wearing a hockey mask so the "face-hugger" in "Alien" can't get at
you).
Once HIV is inside your T4 cells, it needs to copy its RNA to DNA. In order
to do this, it needs to steal the parts for the DNA and some other chemicals
from the T4 cell. The most successful method to prevent this copying is to
provide your cells with chemicals that look like they are the real building
blocks (bases) for DNA, but they have a flaw: they won't allow the next
block in the chain to link in. These drugs are referred to as Chain
Terminators, because they stop the DNA chain from being completed, which
stops HIV from replicating. (Think of jigsaw puzzles where each piece has a
hole and a little extension to fit into the hole of the next piece. All the
pieces link together, extension to hole. Chain terminators have the hole,
but no extension, so the next piece in the puzzle can't snap in.) The only
approved Chain Terminator to fight HIV is called AZT, which stands for 3'-
azido-3'-deoxythymidine. (AZT is also known as Zidovudine and is sold under
the trade name Retrovir). AZT is a "nucleoside analog," that is, a fake or
counterfeit version of thymidine, which is one of the four bases needed for
creating DNA copies. The other Chain Terminators that have been or are
being tested are ddA (2',3'-dideoxyadenosine, a fake, flawed version of
adenosine), ddC (2',3'-dideoxycytosine, the counterfeit of cytosine), and
ddI (2',3'-dideoxyinosine, which gets converted by your body into an
activated form of ddA).
Another stage at which the virus can be fought is to prevent it from
finishing its replication and budding off into more virus. Interferon
appears to disrupt the "final assembly" process of surrounding the newly
duplicated RNA strand of HIV with a protein coat and allowing it to bud off
as a whole new active HIV.
An entirely different approach to treating HIV infection is GM-CSF
(granulocyte macrophage-colony-stimulating factor), which tries to boost
production of cells in the bone marrow. It is hoped that GM-CSF taken in
combination with drugs like AZT (which reduces production of cells in your
bone marrow), will allow higher dosages of AZT with less of a toxic effect
on your body.
The latest name of the game in fighting HIV appears to be combinations of
drugs. Some drugs taken together are much more effective than either of
them taken singly (like the GM-CSF/AZT combination described above). Other
drugs have potent side effects on their own that get lessened if you switch
between two drugs (like the AZT/ddC trials now under way, where AZT is taken
for a while, the switch is made to taking ddC for a while, and then back to
AZT).
The unfortunate reality is that, at the moment, if a drug can be produced
which is strong enough to be effective in killing or inhibiting HIV, it is
also going to have some side effects on your body's normal day-to-day
operation. It is hoped that by trying different combinations of drugs an
effective treatment will be found that stops HIV in your cells and that your
body can tolerate.
With each passing day and every new drug tried in the test tube and finally
in willing, informed human volunteers, we grow another step closer to
figuring out a way to stop HIV. The only three things that will be required
to find a cure for HIV are ingenuity, time, and money. Unfortunately,
funding is often restricted, the number of qualified researchers is limited,
and time is a commodity that is in very short supply.
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The author gratefully acknowledges that much of the material in this article
was derived from the brilliant report in The New England Journal of Medicine
by Dr. Samuel Broder and Dr. Robert Yarchoan of the National Cancer
Institute ("Special Report: Development of Antiretroviral Therapy for the
Acquired Immunodeficiency Syndrome and Related Disorders: A Progress
Report," NEJM, Vol. 316, No. 9, February 26, 1987). Acknowledgment is also
gratefully made to Dr. W. Howard Cyr for patiently answering many obtuse
questions about molecular biology. Any errors, excessive simplifications,
or misunderstandings are my own.
--Andrew Coile
NOTES:
1. The name "HIV" was chosen after lengthy international intrigue (see
Randy Shilts' "And The Band Played On" for more details), some
scientific false starts, and cases of mistaken identity. "HTLV-III"
(Human T-Cell Leukemia Virus type III--but it turned out HIV wasn't a
Leukemia virus, so they changed the "L" to Lymphotrophic), "LAV"
(Lymphadenopathy Associated Virus, named by Luc Montangier at the
Pasteur Institute), etc. have all been replaced, by international
agreement, with the name "HIV." The disease caused by HIV has been
named "AIDS," replacing older terms like "Gay Cancer" (referring
primarily to Kaposi's sarcoma in gay men, an opportunistic infection
made possible by HIV), and "GRID" (Gay-Related Immune Deficiency).
2. Centers for Disease Control Morbidity and Mortality Weekly Report
(otherwise known as the MMWR) gives weekly statistics for the incidence
of AIDS, and contains breakdowns by race, age, risk group, etc.
3. Antiviral Agents Bulletin, Ronald A. Rader and Oskar R. Zaborsky,
Editors. Volume 1, Number 3, June 1988, page 67.
4. Centers for Disease Control Morbidity and Mortality Weekly Report
Supplement: "Revision of the CDC Surveillance Case Definition for
Acquired Immunodeficiency Syndrome," August 14, 1987, Volume 36, Number
1S.
FIGURES:
1. Structure of HIV.
2. HIV attaching to a T4 cell.
3. First stage of reproduction: the RNA is copied to a strand of DNA.
4. The DNA strand is made up of a chain of phosphates and sugars, with
bases attached to the sugars. There are only four bases, and adenosine
will only bind with thymidine, and cytosine will only bind with
guanine.
5. Second stage of reproduction: single DNA strand is replicated to
double DNA strand.
6. The HIV DNA breaks the loop of the T4 DNA, and binds its ends to the
cut ends of the T4 DNA, thus "hiding out" inside the T4 cell.
7. The HIV DNA lying dormant insidase the T4 cell's DNA.
8. The HIV virus bulging out the wall of the T4 cell, preparing to "bud"
off on its own.
9. New HIV cell buds off from the T4 cell and drifts off in search of
fresh prey.
10. DNA being copied. The original is on top, and below it the
corresponding bases are linking together. Remember that adenosine will
always be opposite cytosine, and thymidine will always be opposite
guanine.
11. Once AZT has linked in, the next bases on the chain have no extension
to attach to, so the copy can never be finished. Thus, AZT stops HIV
from successfully replicating.
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SHORTCUTS
HOW TO GET A HANDICAPPED METRO PASS
by Henry L. Trevathan, Jr.
"Shortcuts" aims to alleviate the aggravation of plodding through the red
tape in applying for services in the Metropolitan Washington area. As a
person with AIDS, I have experienced the frustrations of being transferred
from person to person or placed on hold all day listening to a recording.
Needless to say, a great deal of time and energy must be expended when
starting from scratch and not knowing precisely where to begin. In this
issue, I will discuss how a person with AIDS or ARC can apply for a reduced
fare on MetroRail and MetroBus.
STEP ONE: Call the Metro Handicapped and Senior Citizen Assistance Office
and request that you be sent a "Handicapped Form Application." The
office hours are from 8:00 a.m. to 4:30 p.m., Monday through Friday.
The phone number is 962-1245.
STEP TWO: After you receive the application you can fill out the front with
the general basic information asked on most forms.
STEP THREE: Present the application to your physician where he or she will
mark with a check that your condition is temporary or permanent. Also,
your physician must write a brief statement describing your condition
which will qualify you for the reduced rate. For example, my physician
(at my suggestion) wrote that due to diarrhea and weight loss
associated with AIDS, I have difficulty with walking distances and
prolonged standing. Finally, your physician signs the form.
STEP FOUR: You must take the completed application to the Metro Handicapped
Assistance Office located at 600 5th Street, N.W. The office is on the
lobby level tucked away down a quiet hall. The security guard can
point you in the right direction. Present your application and you
will be asked to have your photo taken for your Metro ID card. You
will receive your photo ID at that visit. The whole process took about
15 minutes. While there, be sure to take a brochure which tells you
where you can purchase the special MetroRail tickets. You can get
$4.00 or $8.00 tickets in the lobby of 600 5th Street, N.W., Metro
Center, Giant Food Stores in Prince George's County, bus garages in
Virginia, and some local banks.
STEP FIVE: Enjoy reduced fares on MetroRail and MetroBus. A MetroRail ride
from Cleveland Park/Zoo to National Airport costs 65 cents and a trip
from Union Station to Dupont Circle costs 40 cents. Bus fare within DC
costs 25 cents and within Maryland and Virginia 30 cents. Bus fare
between D.C. and Virginia and D.C. and Maryland costs 55 cents. To
receive reduced fare on MetroBus, you must show the bus driver your
Metro photo ID. You must also present the ID to purchase the MetroRail
tickets.
ADDITIONAL INFORMATION: A temporary ID card is good for 6 to 24 months,
while a permanent card is good for three years. For further
information about Metro services, including routes and connections, you
can call a customer sales representative between 6:00 a.m. to 11:30
p.m., seven days a week, at 637-7000.
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Copyright (C) 1988,1989 by Washington HIV News, all rights reserved.
Permission is granted for non-commercial use only.