fortunately that isn’t very common. The biggest concern with HIV-2 is that there are some classes of HIV medicines that do not work against the virus. None of the drugs in the Non-nucleoside class (efavirenz, rilpivirine, etravirine, doravirne) can suppress HIV-2. Also, some protease inhibitors don’t work (e.g. atazanavir) while others do (e.g. darunavir).
For HIV-1 , the largest category of viruses are in group M and the different strains are referred to as subtypes. Subtypes are based on their genetic similarity and diversity. They are found in different geographical areas. What is amazing to observe is that most developed countries have the same HIV subtype. Throughout North America and Europe but also Latin America and the Caribbean, the predominant strain is HIV-1 subtype B.
This is quite significant because the most research has been done in subtype B virus. Diagnostic tests were developed to detect subtype B and all the drugs we used were developed for their effectiveness against subtype B virus. However, other subtypes predominate in developing countries. The most widespread strain of HIV is subtype C. It is found throughout Southern Africa, parts of east Africa, India and other parts of Asia. Approximately half of all HIV infections in the world are from subtype C virus. As I just mentioned, diagnostic tests early on were developed to detect subtype B virus and oftentimes were not able to recognize infections from other subtypes because of minor differences in their genetic makeup.
This created a problem where HIV infections were sometimes missed here in the US if the person had been infected with a different subtype and may have come from another country. I would say that in the last couple decades, the tests have been improved such that this is no longer a problem. There are differences between different subtypes in how easily they are transmitted sexually and through birth and also how aggressively they cause disease. For example, in the country of Uganda, most people have either subtype A or subtype D virus. But these two are NOT the same! Subtype A viruses have a significantly higher rate of heterosexual transmission than subtype D viruses.
However, in the absence of treatment, subtype D virus causes more damage to the immune system and progresses nearly twice as fast to AIDS as subtype A. The good news is that unlike the case for HIV-2, for HIV-1, all HIV medicines work in all subtypes for the most part.
Now back to the story at hand. The new subtype identified has been designated subtype L. It has been isolated from the Congo in central Africa. From what we can tell so far, all medicines should be