How does HIV work?

HIV is a peculiar virus that, to this day, has scientists across the world working to try and better understand how it operates. It has multiple stages and works slightly differently than other viruses, which means it can often be misunderstood.

Let’s look at what HIV is, how it impacts the body, how modern HIV treatments can keep a person living with HIV healthy, and even prevent HIV transmission!

How does HIV affect the body?

HIV is a virus that attacks the body’s immune system, specifically white blood cells called CD4 cells (sometimes referred to as T cells). HIV invades CD4 cells, replicating and producing many copies of the virus inside the cell before it is destroyed.

As HIV invades your CD4 cells, it damages the immune system. This system is made up of CD4 and CD8 cells that protect the body from bacteria, viruses and parasites.

If the immune system becomes damaged by a virus like HIV, a person becomes much more vulnerable to infections and illnesses. When the amount of HIV in the body reaches a critical threshold, and the immune system has been badly damaged, HIV can progress to AIDS. If this does occur, the body is susceptible to becoming sick and can no longer fight off illnesses it would have been able to otherwise, in extreme cases, leading to death.

Thankfully, in Australia these days, it’s very rare for someone living with HIV to develop AIDS, as we have access to affordable, and in most cases free HIV treatment, which suppresses the virus and helps keep people living with HIV healthy.

How does HIV infect cells?

HIV infects healthy immune cells by attaching to the CD4 receptors and binding to their surface. Once fused to the cell, it begins to instruct it to create copies of the virus. These new HIV viral particles (virions) then leave the cell, floating into the bloodstream to restart the process.

Thanks to scientific advances, medicines are now available that can stop this process. These medicines, known as antiretroviral therapy (ART) or HIV treatment, interrupt and prevent the viral replication process in the body.

What are the stages of HIV infection?

There are three stages of HIV, but with today’s effective treatments, progression to stage three (AIDS) is extremely rare.

Stage 1: Acute HIV Infection

The acute infection happens in the first 2 to 4 weeks after transmission. During this stage, the level of HIV in the blood is extremely high, meaning that after a recent infection is when someone is most contagious. Some, but not all, people will exhibit flu-like symptoms, including fever, headaches, and sometimes even a rash. Read more in our article on the symptoms of an early HIV infection.

The only way to know if you are experiencing an acute HIV infection or if it’s perhaps something else is to get tested.

When a person gets tested for HIV, the pathologist looks for the presence of HIV antibodies or the p24 antigen in the blood sample. It takes time for the virus to replicate and the body to produce an immune response and create antibodies. It can take anywhere from a couple of weeks to as long as 3 months after a potential exposure to HIV before it can be detected in a test. So, if you test within this time, called the window period, you’ll have to test again after 3 months to be sure of the result.

Stage 2: Chronic HIV Infection

 This stage is also called asymptomatic HIV or sometimes clinical latency and occurs in the absence of HIV treatment. During chronic HIV infection, the virus continues multiplying over time as the immune system slowly weakens. Often people experiencing a chronic HIV infection will not exhibit any symptoms at all.

While it’s still possible for HIV to be transmitted during this stage, the risk is lower compared with an acute HIV infection. People living with HIV can eliminate the risk of transmitting HIV to their partners by taking treatment and achieving an undetectable viral load.

Over time, a person on HIV treatment lowers their viral load (the number of copies of the virus in the blood), improving their health. Usually, a person on ART can reduce their viral load to a level known as ‘undetectable’. When a person has an undetectable viral load, it means they can’t pass on HIV to others!

Without treatment, the chronic HIV infection stage of HIV can last 10 years or longer before progressing to stage 3 (although, for some people, it’s faster).

Stage 3: Acquired Immunodeficiency Syndrome (AIDS)

 This is the most severe stage of HIV but is far less likely now, thanks to the development of ART. If you’re living with HIV and taking medication as prescribed, it’s highly unlikely you’ll ever develop into stage 3.

People who develop AIDS have a severely damaged immune system, leading to severe illnesses known as opportunistic infections. The immune system becomes so damaged that diseases like tuberculosis, pneumonia, and leukaemia can’t be fought off as they can be by a healthy immune system.

Can HIV be removed from the body?

Once someone acquires HIV, it remains in the body forever regardless of HIV treatment.

While there isn’t yet a cure for HIV, the virus can – in extremely rare and fortunate cases – go into what’s called ‘remission’. This is where the virus can be suppressed by the immune system without the need for HIV treatment. People within this group are known as ‘elite controllers’. We still don’t completely understand why their immune systems can fight off HIV, but research is ongoing to see if their suppression of HIV might lead to insights that could progress HIV cure research.

However, for most people living with HIV, it is the wonders of modern HIV treatment that help ensure they can continue to live a near-normal life and have a life expectancy similar to their HIV negative counterparts.

What’s next?

If you are concerned about exposure to HIV, book an appointment with a sexual health clinic or doctor/GP. Get tested for HIV and other STIs once every three months if you are sexually active. Find a place to get tested near you.

Or, if you have any questions about HIV and are in NSW, you can call the NSW Sexual Health Infolink on 1800 451 624 to speak to a sexual health nurse.