Question
What is the difference between HIV-1 and HIV-2?
27 September 2006. Related: All topics, Other tests.
What is the difference between HIV1 and HIV2 with regards to structure, function, occurence and survival in the environment?
Answer
HIV-1 and HIV-2 are two different viruses. HIV-1 is the main family of HIV and accounts for 95% of all infections worldwide. HIV-2 is mainly seen in a few West African countries. The spread in the rest of the world is negligible.
Although HIV-2 generally progresses more slowly than HIV-1, some HIV drugs (NNRTIs like nevirapine and efavirenz) do not work against HIV-2.
On a structural level HIV-1 and HIV-2 have important genetic differences. A technical description of the difference is that the vpu gene found in HIV-1 is replaced by the vpx gene in HIV-2. In addition, the protease enzymes from the two viruses, which are aspartic acid proteases and have been found to be essential for maturation of the infectious particle, share about 50% sequence identity.
There are, however, differences in substrate and inhibitor binding between these enzymes. Most notably between the CGP 53820 inhibitory binding.
On functional level, there is a difference between the two viruses in terms of how easy it is for the virus to infect someone. HIV-1 enters the immune system by attaching onto the CD4+ receptor found on the surface of certain white blood cells. HIV-2 has a harder time gaining such a foothold.
So HIV-2 generally progresses much more slowly, with lower viral laod and slower risk of becoming sick. However, some HIV drugs (including NNRTIs) are not active against HIV-2.
Both viruses are fragile and highly susceptible to physical and chemical agents and therefore do not survive well outside the human body. HIV in blood or sexual fluid for example is not infectious after it has been outside the body for a few minutes.
Notes: this answer was updated in January 2018.
Hi Elizabeth,
It doesn’t matter that you’ve not been to Western Africa, if you’ve had sex without a condom with someone with HIV this will explain why you’ve HIV-2.
Has treatment been discussed with you?
I was told I have HIV 2 possitive but i never been in Africa or such thing but I had sex unprotected no comdom
Hi Maxwell,
I hope you don’t mind but I’ve edited your comment to make it much shorter. I’m sorry but i-Base doesn’t have resources to answer questions on testing and risk. All frequently asked questions about this are here.
Hi, on May 27th 2018, I had received oral sex from a transgender in india. She had used condem. But I was not sure,
whether that condem is teared. Could you please advise me if there is any chance of hiv infected and any tests that need to be taken. And any treatment that can control hiv.
Hi R.K. The index value is an HIV test result. We don’t answer questions on testing but please see questions 1 and 8 here.
Hello, My friend is HIV1 positive patient and his index value is 164.5. is there any correlation between high index value and stage of HIV.
Hi Krish, HIV-1 and HIV-2 are two different viruses. They are not different stages of HIV. Most people, if they are HIV positive, have HIV-1. So about 95% of people have HIV-1. HIV-2 is mostly in west Africa. Some drugs that treat HIV-1 don’t work with HIV-2. It’s a good idea for your friend to talk to the doctor about what treatment would be best for him. Here’s a guide to starting treatment (ART).
Hi Roy
I’m not the person. Actually my friend is suffering… He had HIV positive I think… He want to know which one is starting stage and ending stage in HIV negative or HIV positive…?
Hi Krish, There are some differences – as described above. Are you on treatment (called ART)? What meds are you taking?
Hi
Which one is more dangerous, not curable and not responding to drugs HIV1 or HIV2?