[[link removed]]

HIV AND IMMUNITY: UNDERSTANDING THE BATTLE AND THE BREAKTHROUGHS  
[[link removed]]


 

Jess Steier, DrPH and Aimee Pugh Bernard, PhD
December 1, 2025
Unbiased Science
[[link removed]]


*
[[link removed]]
*
*
[[link removed]]

_ On World AIDS Day, how immunology and public health transformed HIV
_

,

 

_This article is a collaboration with __Immunology Explained_
[[link removed]]_, an initiative by the American
Association of Immunologists to connect you to the science that
protects your health._

I (Jess) was a teenager when I first watched _Philadelphia_. Tom
Hanks, gaunt and dying, fighting for his dignity in a courtroom while
his body failed him. That was 1993, and that was AIDS – a death
sentence delivered with a diagnosis. I remember crying during the
opera scene and thinking this disease was about endings.

Years later, in graduate school, AIDS became something else entirely
– the perfect teaching example for epidemiology students learning
about incidence versus prevalence. Our professors would draw those
curves on the board: incidence dropping like a stone after 1996, while
prevalence climbed steadily upward. It took me a moment to understand
what that paradox meant: fewer people were getting HIV, but more
people were living with it. They were _living_ with it.

That shift – from death sentence to chronic condition – represents
one of the most remarkable scientific victories of our time. And at
its heart lies our evolving understanding of the immune system
itself...

_WORLD AIDS DAY IS DECEMBER 1, AND A TIME TO HONOR LIVES LOST,
CELEBRATE PROGRESS, AND RECOMMIT TO ENDING THE EPIDEMIC._ Human
Immunodeficiency Virus (HIV)/Acquired Immunodeficiency Syndrome (AIDS)
was once a global health crisis with no cure and little hope. Today,
thanks to decades of scientific breakthroughs and public health
action, HIV is no longer a death sentence and is now a manageable
chronic condition. But the fight isn’t over. Millions still lack
access to treatment, new infections continue, and stigma remains a
barrier to care. Ongoing research into HIV’s interaction with the
immune system and sustained investment in prevention strategies are
critical to protect communities and move closer to long-term control.

TWO KEY PILLARS STRENGTHEN OUR RESPONSE TO HIV AND IMPROVE GLOBAL
HEALTH:

* IMMUNOLOGY INSIGHTS: Understanding how HIV attacks CD4 T cells and
how treatments disrupt the virus’s life cycle drives innovation in
therapy and prevention.
* PUBLIC HEALTH TOOLS: Strategies like _U=U_ (Undetectable =
Untransmittable) and PrEP (Pre-Exposure Prophylaxis) dramatically
reduce transmission and protect communities.

THE IMMUNOLOGY BEHIND THE BATTLE: HIV TARGETS AND WEAKENS THE IMMUNE
SYSTEM

HIV is a retrovirus
[[link removed]]that
targets CD4+ helper T cells, the “generals” of the immune system
that coordinate immune system defenses. The virus binds to the CD4
receptor and a co-receptor (usually CCR5) to enter the cell and take
it over, ultimately resulting in the death of the cell.

Once inside, HIV begins a clever takeover
[[link removed]]:

BINDING AND ENTRY: The virus attaches to CD4 and CCR5, markers on the
outer surface of CD4+ T helper cells, and fuses with the cell membrane
to enter the cell.

REVERSE TRANSCRIPTION: HIV converts its RNA genome into DNA, the
nucleic acid of our human genomes, using an enzyme called reverse
transcriptase, which it brought with it to ensure cellular takeover.
This step – reverse transcription - is a major target for many HIV
drugs since human cells do not contain or use this enzyme. It is
unique to HIV infected cells.

INTEGRATION: The viral DNA is then integrated or woven into the
cell’s own genome by another enzyme, provided by the HIV virus
itself, called integrase. This viral genome integration into our own
DNA makes the infection permanent.

REPLICATION AND RELEASE: The hijacked cells become a viral factory,
churning out billions of new viruses and eventually dying in the
process.

Source:
[link removed]
[[link removed]]

By destroying CD4+ T helper T cells, HIV disables the immune
system’s command center.

PROGRESSION TO ACQUIRE IMMUNODEFICIENCY SYNDROME (AIDS)

 
As CD4 cells are destroyed, the immune system collapses. When CD4
count falls below 200 cells/mm³, AIDS is diagnosed, leaving the body
vulnerable to opportunistic infections such as Pneumocystis pneumonia
(PCP), tuberculosis, cytomegalovirus, and fungal infections like
candidiasis. These illnesses take advantage of a weakened immune
system and can be life-threatening without treatment.

THE PREVENTION AND TREATMENT REVOLUTION

 
Antiretroviral therapy (ART)
[[link removed]]works
by blocking key steps in HIV’s cycle, stopping the virus from
multiplying and helping the immune system survive. Different drug
classes target specific viral enzymes: reverse transcriptase
inhibitors prevent the virus from converting its RNA into DNA,
integrase inhibitors stop viral DNA from inserting into the host
genome, and protease inhibitors block the assembly of new virus
particles. By halting replication at these critical points, ART
reduces the amount of virus in the blood to undetectable levels,
allowing CD4 T cells to recover and restore immune function.

Ending HIV requires more than science - it demands access, equity, and
sustained funding. Progress is being driven by a combination of
scientific innovation, effective treatments, and public health
strategies that prevent transmission and improve access to care.

THE POWER OF “KNOW YOUR STATUS”

 
Testing is the entry point to care. Rapid tests and even home kits
make it easier than ever to learn your HIV status. This matters
because of the UNAIDS 95-95-95
[[link removed]]
targets for 2025:

* 95% of people living with HIV know their status
* 95% of those diagnosed are on treatment
* 95% of those on treatment achieve viral suppression

Global progress is uneven. Some countries have met these targets,
while others lag behind, with testing coverage below 75%.

UNDETECTABLE = UNTRANSMITTABLE (U=U)

 
Science is clear: People living with HIV who maintain an undetectable
viral load through ART cannot sexually transmit the virus. This
principle, validated by major studies like HPTN 052 and PARTNER, is
now endorsed globally. U=U is a cornerstone
[[link removed]] of HIV
prevention that dismantles stigma, empowering people living with HIV
to live full, healthy lives.

COMPREHENSIVE PREVENTION TOOLS

 

* PREP (PRE-EXPOSURE PROPHYLAXIS
[[link removed]]):
A daily pill or long-acting injection for HIV-negative individuals to
prevent infection. When taken as prescribed, PrEP reduces HIV risk
from sex by about 99% and from injection drug use by at least 74%.
* PEP (POST-EXPOSURE PROPHYLAXIS
[[link removed]]): Emergency
medication taken within 72 hours after a possible exposure to HIV.
* COMBINATION PREVENTION: The most effective approach combines PrEP,
U=U, condoms, and harm reduction strategies.

A FUTURE WITHOUT AIDS - SCIENCE MAKES IT POSSIBLE, FUNDING MAKES IT
REAL

 
Science only works when programs deliver it. Initiatives like PEPFAR
[[link removed]]
and the Global Fund [[link removed]] provide the
infrastructure for testing, treatment, and prevention. PEPFAR alone
has saved an estimated 26 MILLION LIVES and enabled millions of babies
to be born HIV-free. Sustained investment is essential. Funding
prevention and treatment costs far less than managing a growing
epidemic and, most importantly, saves lives.

Science and public health have transformed HIV
[[link removed]]
from a fatal disease to a manageable condition. But the finish line of
ending AIDS as a public health threat requires action:

* GET TESTED
* KNOW U=U
* ADVOCATE FOR FUNDING AND FIGHT STIGMA

On this World AIDS Day, let’s honor scientific progress and commit
to a future where HIV is history by continuing to invest in science,
expanding access to life-saving treatments, and fighting stigma so
that every person, everywhere, can live free from the threat of HIV.

That teenager watching _Philadelphia_ couldn’t have imagined a world
where HIV-positive people would have near-normal life expectancies,
where a daily pill could prevent infection, where ‘undetectable’
would equal ‘untransmittable.’ But here we are, living proof that
science – particularly immunology – can rewrite even the darkest
stories.

If you’d like to support this work, please consider a paid
subscription to our Substack. You can also make a tax-deductible
donation to The Center for Unbiased Science and Health
[[link removed]] (CUSH), our nonprofit that funds
educational initiatives like this one.

Stay Curious,

Unbiased Science

_JESS STEIER, DrPH @drjessicasteier is a public health scientist, host
of Unbiased Science, and quirky and empathetic science communicator._

_AIMEE PUGH BERNARD, PhD @funsizeimmuninja is an Immunologist,
educator, Science Communicator and Science Advocate_

_UNBIASED SCIENCE breaks down complex health and science topics
through patient, evidence-based explanations that respect both
skepticism and nuance. Through our weekly podcast, daily social media
content, and in-depth newsletter analyses, we help people become
better consumers of scientific information._

_Our approach is simple: no nonsense, just science. We take time to:_

* _Examine evidence thoroughly and objectively_
* _Explain complex topics with patience and clarity_
* _Address common questions and concerns_
* _Make scientific concepts accessible to everyone_
* _Bridge the gap between skepticism and science_

_WANT TO SUPPORT OUR WORK? Please subscribe to our Substack and share
our content. Everything we write stays free forever—we believe
public health information belongs to everyone. Paid subscriptions help
us spend more time on deep-dive investigations like this one,
following the data wherever it leads._

* Science
[[link removed]]
* Medicine
[[link removed]]
* health
[[link removed]]
* HIV/AIDS
[[link removed]]
* immunology
[[link removed]]
* public health
[[link removed]]
* immune system
[[link removed]]
* RNA
[[link removed]]
* DNA
[[link removed]]

*
[[link removed]]
*
*
[[link removed]]

 

 

 

INTERPRET THE WORLD AND CHANGE IT

 

 

Submit via web
[[link removed]]

Submit via email
Frequently asked questions
[[link removed]]
Manage subscription
[[link removed]]
Visit xxxxxx.org
[[link removed]]

Bluesky [[link removed]]

Facebook [[link removed]]

 




[link removed]

To unsubscribe, click the following link:
[link removed]