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 Dee, Shovelling cow manure is not a way that HIV 1 or 2 is transmitted. You can find out more about how HIV is not transmitted here.
Can a person contract HIV 2 by shoveling cow manure for a period of time?
Hi Kelly,
Once someone has an undetectable viral load they aren’t able to infect someone when having sex. Please see the following:
http://i-base.info/htb/32308
Not being able to transmit when undetectable is now widely accepted by leading scientist and doctors. These include the British HIV Association, UNAIDS and the US CDC.
I am happy to look at evidence that disprove the Swish Statement and the PARTNER study if oyu would like to send this.
Are you serious? You can contract HIV even if the person is undetectable. Just because a person’s CD4 count maybe good and their viral load is undetectable does not mean that they are cured from the virus.
Hi Jame,
This is false. Condoms are not packed with HIV.
some people say,sme condoms are packed with the virus, true or false?
Hi Sulaiman,
Yes its very possible that someone can have HIV2 and not HIV1. However, HIV2 is less common and is usually concentrated in Western Africa.
is it possible for someone to have HIV-2 and not have HIV-1?
Hi Kanji,
If your girlfriend is on medication and her viral load is undetectable, then no you aren’t at risk. Please see here for more info:
http://i-base.info/htb/32308
Hi! so, my girlfriend just told me that she has HIV 1! can i be infected with it? she says it cannot infect me! dunno which is which?