Inside the body: how HIV changes the immune system

The room is silent. Only the cold light of the phone illuminates her face.

She's been reading testimonials online for over an hour. Stories of people who talk about HIV with disconcerting ease. They describe it as manageable, almost commonplace. An infection that, thanks to modern medicine, can be kept under control with a simple daily pill.

Some even go further.

They speak of a radical decision: to stop living in fear of the virus and, instead of avoiding it for life, to contract it voluntarily. To turn the threat into a fait accompli. After all, they say, HIV is no longer what it was thirty years ago.

In some corners of the internet this idea even has a name: bugchasing.

The term, as chilling as it is unsettling, describes the deliberate pursuit of HIV infection. These are people who choose to voluntarily expose themselves to the virus, reasoning that if medicine has managed to make the disease treatable, perhaps the best way to stop fearing it is simply to acquire it.

The words are repeated: manageable, effective treatment, normal life. Logic begins to take shape in her mind in a disturbing way. If the infection is manageable… why continue to fear it?

The idea is absurd. But also seductively simple.

Just one moment. One decision. And the fear disappears forever.

This phenomenon exists. And it reveals something deeply troubling: the extent to which society's perception of HIV has changed. Scientific advances have radically transformed its prognosis, but they have also generated a dangerous illusion: the idea that the virus is little more than a medical inconvenience that is easily resolved.

Nothing could be further from the truth.

HIV remains one of the most complex viruses known to medicine. It infects the immune system, alters the very architecture of our defenses, and necessitates lifelong treatment. Its impact extends far beyond taking a pill each morning.

That someone would even consider voluntarily infecting themselves is, at its core, a sign of just how much misinformation can distort our understanding of science and health.

Therefore, at Science Driven, we will rigorously analyze what really happens when HIV enters the body, how it interacts with the immune system, and what it means to live with this virus in today's world.

What is HIV?

HIV is the human immunodeficiency virus, a retrovirus that infects and progressively weakens the immune system. Its most significant characteristic is its ability to invade certain key cells of our defenses, especially CD4 T lymphocytes, which coordinate much of the immune response against infections and other pathogens.

Unlike many viruses that cause acute infections and disappear from the body after a few days or weeks, HIV has a very different biological strategy. After entering the body, it integrates its genetic material into the DNA of the cells it infects. This allows it to remain in the body persistently and use the cellular machinery to produce new copies of the virus.

This mechanism explains why HIV cannot be easily eliminated from the body. Although current treatments are able to block its replication very effectively, the virus can remain hidden in cellular reservoirs for years.

Differences between HIV, AIDS and seropositivity

In everyday language, the terms HIV, AIDS, and seropositive are often used interchangeably. However, from a medical perspective, they describe distinct realities within the same biological process.

• HIV is the virus itself: the infectious agent responsible for the disease. When a person becomes infected, the virus begins to replicate in the body and interact with the immune system, especially with CD4 lymphocytes.
• The term seropositive refers to a person who has antibodies against HIV in a blood test. This means the immune system has recognized the virus and generated a detectable immune response. Being HIV-positive does not necessarily mean the person is ill or has symptoms.
• AIDS, on the other hand, is the most advanced stage of the infection. The acronym stands for acquired immunodeficiency syndrome and describes a condition in which the immune system is severely weakened, potentially leading to death. At this stage, the body loses much of its ability to defend itself against infections and certain types of cancer that would normally be controlled by the immune system.

In other words, HIV is the virus, seropositivity is evidence that the body has been exposed to it, and AIDS represents an advanced clinical phase of the infection when the immune system has suffered significant deterioration.

What happens in the body after HIV infection?

When HIV first enters the body, a silent race begins between the virus and the immune system. During the first few days after exposure, the virus replicates rapidly in the cells it encounters, especially in lymphocyte-rich tissues of the immune system, such as the lymph nodes.

In this initial phase, known as acute HIV infection, the amount of virus in the blood can increase very rapidly. Some people experience symptoms similar to those of a severe viral infection (fever, sore throat, fatigue, swollen lymph nodes) while in others the infection goes virtually unnoticed.

At the same time, the immune system begins to react. The body's defenses identify the presence of the virus and generate antibodies and cells capable of attacking it. This immune response manages to partially reduce the amount of circulating virus, but it does not eliminate it completely.

After this initial phase, the infection enters a longer, more silent period. The virus remains present in the body and continues to replicate at lower levels, particularly in the lymph nodes and other tissues of the immune system. During this stage, which can last for years, many people experience no noticeable symptoms.

However, even though the infection may appear stable from the outside, the virus continues to interact with the immune system constantly. This slow and persistent process is what, over time, can lead to the progressive weakening of defenses if the infection is left untreated.

How does HIV affect the immune system?

The most distinctive feature of HIV is its ability to directly attack the body's defense system. While many viruses infect cells of the respiratory system, liver, or nervous system, HIV primarily targets the cells that coordinate the immune response, the CD4 lymphocytes.

These cells act as conductors for other defenses, such as B lymphocytes (responsible for producing antibodies) and cytotoxic T lymphocytes (which destroy infected cells). When CD4 cells function correctly, the body can organize complex responses against bacteria, viruses, and other pathogens.

HIV uses a very specific strategy to invade these cells. The virus first binds to the surface of the CD4 lymphocyte using specialized proteins and, after fusing with the cell membrane, introduces its genetic material inside. Once inside, it uses an enzyme called reverse transcriptase to convert its viral RNA into DNA, which is then integrated into the genome of the infected cell.

This step is crucial: by integrating into the cell's DNA, the virus transforms the cell itself into a factory for producing new viral particles. Each time the cell produces new copies of the virus, these can infect other nearby CD4 cells, progressively spreading the infection.

In other words, HIV inserts a copy of its genetic material into the DNA of the cell it infects. From that moment on, the virus ceases to be merely an external invader and becomes part of the cell's own genetic code, using its machinery to produce new viral particles.

Viral load: what it means and why it's so important

One of the key concepts for understanding the progression of HIV infection is viral load. This term describes the amount of virus present in the blood of an infected person and is measured using laboratory techniques that quantify the number of viral RNA copies per milliliter of blood.

In simple terms, viral load allows us to estimate how much virus is actively circulating in the body at a given time. The higher this number, the greater the virus's replicative activity and, therefore, the greater the potential impact on the immune system.

Achieving an undetectable viral load has very important medical consequences. On the one hand, it protects the immune system by limiting the progressive destruction of CD4 lymphocytes. On the other hand, it decisively reduces the virus's transmissibility.

In fact, numerous scientific studies have demonstrated a principle now widely accepted in medicine and public health: U=U (Undetectable = Untransmittable), meaning undetectable equals untransmittable. When a person with HIV maintains an undetectable viral load thanks to treatment and adheres to it correctly, they do not transmit the virus to their sexual partners.

There is also a lesser-known phenomenon called superinfection. Even if two people are HIV-positive and neither has developed AIDS, unprotected sex can allow the transmission of a second variant of the virus between them. When this happens, the body can be confronted with a different viral strain than the one already present, increasing the viral load and causing both partners to develop AIDS.

This aspect dismantles one of the arguments that sometimes appears in irresponsible discourses associated with bugchasing : the idea that, once infected, it would no longer be necessary to continue taking precautions in sexual relations with other HIV-positive people.

Medical complications of HIV

When HIV is not diagnosed or treated properly, the prolonged interaction between the virus and the immune system can lead to a range of medical complications. These do not appear immediately after infection, but rather develop slowly as the immune system loses its ability to coordinate its defenses.

Among the most frequent complications are recurrent infections, chronic inflammation, and increased susceptibility to microorganisms that rarely cause illness in people with an intact immune system. Some of these infections can affect the lungs, the digestive system, the nervous system, or the skin.

HIV also has a significant impact on the management of other serious illnesses, such as cancer. When a person with HIV infection develops a tumor, the oncological approach changes significantly. The state of the immune system, CD4 lymphocyte count, viral load, and potential interactions between antiretroviral drugs and cancer treatments influence many therapeutic decisions.

In some cases, these limitations can restrict certain strategies, necessitate dose adjustments, or increase the complexity of treatment. Consequently, the coexistence of HIV and cancer is associated in many clinical settings with a higher risk of complications and higher mortality than in patients without HIV infection.

HIV-associated diseases

Among the most characteristic diseases associated with HIV are opportunistic infections. These are infections caused by microorganisms that do not normally cause serious illness in people with a competent immune system, but which can become very dangerous when defenses are weakened. These include Pneumocystis jirovecii pneumonia, tuberculosis, esophageal candidiasis, cerebral toxoplasmosis, and certain cytomegalovirus infections.

HIV is also associated with an increased risk of certain cancers, especially those related to viral infections or prolonged immunosuppression. Among the best known are Kaposi's sarcoma, non-Hodgkin lymphoma, and invasive cervical cancer, historically considered AIDS-defining illnesses. In addition, people with HIV may have an increased risk of other non-AIDS-defining cancers, such as certain anal, liver, or lung cancers.

Beyond infections and tumors, chronic HIV infection is also linked to an increased risk of cardiovascular, kidney, liver, and neurological diseases. Part of this risk stems from accumulated immune damage, but also from persistent inflammation that can persist even during seemingly stable phases of the infection.

HIV treatment: how antiretroviral therapy works

During the first decades of the epidemic, HIV infection was almost inevitably associated with progression to AIDS and high mortality. However, the development of antiretroviral therapy has radically transformed this situation.

Antiretroviral therapy does not eliminate the virus from the body, but it works by blocking different stages of its replication cycle. The medications used are designed to interfere with key processes the virus needs to multiply within the cells of the immune system.

There are several classes of antiretroviral drugs, each targeting a different point in the viral cycle. Some inhibit reverse transcriptase, the enzyme the virus uses to convert its RNA into DNA inside the infected cell. Others block integrase, preventing viral genetic material from integrating into the host cell's DNA. There are also drugs that interfere with viral protease, which is necessary for assembling new infectious particles.

Modern treatment typically combines several of these medications into a single therapeutic strategy. This approach, known as combination therapy, dramatically reduces the virus's ability to replicate and decreases the risk of resistant variants emerging.

When treatment is followed consistently, viral replication can be reduced to extremely low levels, allowing the immune system to recover and CD4 lymphocytes to gradually increase. In many cases, this allows the infection to be kept under control for decades.

Can a person with HIV lead a normal life?

Today, thanks to antiretroviral therapy, many people living with HIV can have a life expectancy close to that of the general population. When diagnosis is early and treatment is followed correctly, viral replication can be kept under control and the immune system retains much of its functionality.

Under these conditions, many people with HIV lead fully active working, social, and family lives. Even so, treatment must be continued, and medical follow-up remains essential for long-term control of the infection.

Exceptional cases of HIV cure

Although current treatments allow for very effective control of the infection, completely eliminating HIV from the body remains one of the greatest challenges in modern medicine. The virus has the ability to hide in cellular reservoirs where it remains dormant for years, making its eradication extremely difficult.

However, in recent decades some exceptional cases of cure have been documented. The most well-known is the so-called Berlin patient, a man with HIV who received a bone marrow transplant to treat leukemia. The donor had a rare genetic mutation, known as CCR5-delta32, which confers natural resistance to the virus. After the transplant, HIV was no longer detectable in his body.

Similar cases have subsequently been described in other patients, such as the so-called London patient and the Düsseldorf patient. In all of these cases, the cure occurred after stem cell transplants performed to treat serious hematological diseases.

Even so, these procedures are extremely complex, risky, and are not considered a therapeutic strategy applicable to most people with HIV.

Today, the realistic goal of medicine remains to keep the virus under control through antiretroviral treatment while research continues in search of a safe and accessible cure.

Stigmas and false myths about HIV

Few infections have been as surrounded by fear, misinformation, and social stigma as HIV. During the early years of the epidemic, scientific ignorance and media impact generated a perception of the virus deeply marked by fear, contributing to the emergence of numerous myths that still persist today.

One of the most widespread misconceptions is that HIV is easily transmitted in everyday life. In reality, the virus requires very specific transmission routes, such as contact with blood or bodily fluids under certain circumstances. Common activities like sharing utensils, hugging, kissing, or living with a person with HIV do not pose any risk of transmission.

Another common myth is associating HIV exclusively with certain groups or lifestyles. From an epidemiological point of view, the virus can affect anyone exposed to transmission routes, regardless of their sexual orientation, age, or social context.

Medical advances have also debunked many misconceptions about the progression of the infection. Today we know that a person with HIV who adheres to their treatment and maintains an undetectable viral load can lead a long and active life, and cannot transmit the virus sexually.

Fear, discrimination, and misinformation can hinder early diagnosis and access to treatment, two key elements for controlling the infection and improving the health of those living with the virus.

Frequently Asked Questions about HIV

What does HIV do to the immune system?

HIV mainly targets CD4 T lymphocytes, which are key cells in coordinating immune defense. As these cells decline, the body becomes less effective at controlling infections and certain cancers.

Why can HIV affect the body beyond the immune system?

Its impact does not stop at lowering defenses. Persistent viral activity and chronic inflammation can influence multiple organs and systems, including the brain, blood vessels, digestive tract and metabolism.

Does having HIV mean a person will always feel ill?

No. Many people can remain without obvious symptoms for years, especially early on. That is one reason HIV can progress silently if it is not diagnosed and treated.

What is the difference between HIV and AIDS?

HIV is the virus itself, while AIDS is the most advanced stage of infection, when the immune system is severely weakened and the risk of opportunistic disease rises sharply.

What are opportunistic infections?

They are infections that take advantage of a weakened immune system. In advanced HIV, illnesses such as tuberculosis, certain pneumonias, candidiasis or cryptococcal meningitis may appear more easily or behave more aggressively.

Can HIV treatment stop the damage caused by the virus?

Antiretroviral treatment cannot remove HIV completely from the body, but it can suppress viral replication very effectively. This allows the immune system to recover part of its function and greatly reduces the risk of complications.

Can a person with HIV live a normal life?

In many cases, yes. With early diagnosis, consistent treatment and regular medical follow-up, many people with HIV can have a life expectancy close to that of the general population.

What does it mean to have an undetectable viral load?

It means the amount of virus in blood is so low that standard laboratory tests cannot detect it. When that suppression is maintained with treatment, sexual transmission does not occur.

Are there new scientific advances changing the future of HIV?

Yes. Long-acting therapies and preventive strategies are transforming care, and research continues into broadly neutralizing antibodies, therapeutic vaccines and cure approaches. Even so, there is still no universally applicable cure.

How common is HIV worldwide today?

HIV remains a major global health issue. Tens of millions of people are living with the virus worldwide, although access to diagnosis and treatment has improved dramatically in recent years.