Saturday, 3 January 2015

An HIV-free future?

Apologies for not posting in a while! I've finally organised myself and got a list of posts I'm planning to write - and from now on will post every fortnight.. so hopefully I should be better at keeping on top of posts!

Also, this post is a follow up to a topic covered on the radio show I have recently become a part of - the Fuse FM's Faculty of Life Sciences Society Show for my university, University of Manchester. If you would like to listen to the podcast of the show concerning this topic, click here.

The World Health Organisation estimates around 34 million people around the world are living with HIV. The 1st December 2014 was also World AIDS Day, and recently there has been a wealth of news stories claiming HIV may even be evolving to become less resistant.

But, what is HIV? The Human Immunodeficiency Virus is the pathogen that causes AIDS (Acquired ImmunoDeficiency Syndrome), and belongs to a group of viruses called lentiviruses that are normally characterised by a long incubation period, which is the time elapsed between exposure to a pathogen (something that causes disease) and when the symptoms of the disease begin to present. Without treatment, the average survival time after infection with HIV is only estimated to be 9 to 11 years, but this does depend on the subtype of HIV a person is infected with. AIDS is the syndrome that results, and is a condition in which over time the immune system gets progressively worse and worse, and eventually allows for opportunistic infections and cancers to thrive, as the ability to fight infections and disease is weakened. 


Source: UN AIDS 2008 Global Report
The estimated number of people living with HIV/AIDS globally in 2008.

There are many ways in which HIV can be transmitted, but by far the most common is via unprotected sex; the Health Protection Agency cited 95% of the diagnosed cases in 2011 resulting from sexual contact. The virus can also be passed on from mother to child during pregnancy, through sharing infected needles etc. Worryingly, up to 1 in 5 people with HIV are unaware that they are infected with the virus - and this can be partly attributed to the long incubation period HIV has as described above.

AIDS was first observed in the US in 1981, and the initial cases seemed to be confined to homosexual men and injection drug users. These were spotted as unusual due to the fact they showed symptoms of a rare type of pneumonia (Pneumocystis pneumonia, or PCP), which normally only manifested in people with an especially compromised immune system. Soon after this, more gay men began to present with a rare skin cancer called Kaposi’s sarcoma (KS). As more and more cases of men with PCP and KS emerged, more doctors were called in to find the route cause. Research progressed, and in 1986 both HTLV and LAV were renamed as HIV.


Source: The Telegraph/Alamy
A representation of HIV in the blood.

More recently, a team of researchers at University of Oxford have showed that the virus is being ‘watered down’ as it adapts to our immune system. This means the HIV was taking a longer amount of time to cause AIDS. Some researchers even suggested that the virus may become “almost harmless” as it continues to evolve. The team of researchers observed this process by comparing Botswana to South Africa - Botswana had been dealing with an HIV problem a decade longer than S. Africa, and interestingly the ability of HIV to replicate is now 10% lower in said country. This shows the HIV virus changing through evolution, and as a result its ability to cause disease is declining.

Professor Philip Goulder from the Oxford research team says this is happening because every so often HIV infects someone with a particularly strong immune system, and the virus “can get flattened or make a change to survive, and if it has to change then it will come with a cost”. This cost is a lesser ability to replicate, and therefore means that the virus is less infectious. Therefore, the time between HIV infection and AIDS is longer.

This research is encouraging stuff. Currently there is no cure currently available, but there are treatments to enable those infected to live a long and healthy life. Once diagnosed with HIV, the normal course of treatment involves regular blood tests, to gage the levels of virus in the blood. This is calculated by measurement of CD4+ve lymphocyte cells in the blood (CD4+ve cells are a type of white blood cell important for fighting infection). HIV binds to and enters CD4 cells, becoming a part of them. This means that when CD4 cells multiply to fight infection, they are making more copies of the HIV virus too. Therefore, a blood test for CD4 cell count will be able to show the level of HIV infection in the body.


Source: CDC & PHIL
Microscope image showing HIV (green) budding from a lymphocyte.

Anti-retrovirals (ARVs) are a type of drugs that work by stopping the virus replicating in the body, therefore allowing time for the immune system to repair itself and prevent further damage. The team from Oxford University suggested that anti-retroviral drugs might be forcing HIV to evolve into milder strains. Interestingly, normally a patient is told to take 3 or more types of ARV, as HIV can quickly adapt and become resistant to one type of ARV.

A widely used approach in HIV cure research is the ‘kick and kill’ method – this means reactivating the latest proviral DNA (the kick), which means the HIV (previously hidden from the immune system), starts to churn out the virus, in a way that’s visible to the immune system, and allows for the virus to be susceptible to ARV therapy (ARVT).

Although there is no widely available or singular accepted cure, there have been 4 cases (1 baby and 3 adults) that have been reported to have completely cleared their HIV infections. The baby, born in 2013, tested positive for HIV 30 hours after birth. ARVT was immediately given and then used for 18 months after. At 26 months, the clinical tests used to detect HIV in the child came back negative – the child was able to control the infection. However, this is unlikely to be effective on adults as the child was treated so quickly after discovery of the virus.

A huge factor in helping those with HIV/AIDS is destigmatisation of the disease. The fear surrounding the emerging HIV epidemic in the 1980s is still around today. Back then, very little was known about the disease, which made people more afraid of those infected. Some countries have laws that can exacerbate the stigma that HIV positive people feel. For example, Uganda passed a bill in 2014 to enforce anti-homosexuality legislation. The Chinese government also now enforces a compulsory HIV test for anyone applying for a study/work visa longer than 6 months. In the UK you can be prosecuted if you pass the virus to someone else, even if it was unknowingly and without intent.


Source: Niki K Aids
The 'Red ribbon' is used as a symbol of solidarity for those affected by HIV.

Fortunately, HIV is often the subject of conversation and regularly receives large amounts of funding to pump into research projects looking to find a cure. The recent research carried out by the team in Oxford can provide some hope for those with the disease, and the cases of completely cured patients can act as an example and pave the way forward for future treatments.

What do you think? Does HIV/AIDS receive too much funding compared to other preventable disease? Should we be doing more to destigmatise the disease? Let me know in the comments section below! 

2 comments:

  1. Great post. I think it's difficult to say which diseases 'deserve' more funding but I think its fantastic that HIV is now comparable to diabetes in terms of controble with medical help.

    xXx

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