Dr. Pierone, why did you leave out "E" as one of the M Group subtype infections?
Sep 19, 2003
Thank you for the invaluable advice you give. I noticed when you answered a question from someone from Cameroon, that you referred to 9 "pure" subtypes of Group M HIV infection - but you left out subtype E. I have read that subtype E is the most prevalent subtype causing infection in Thailand and other parts of South East Asia. It is also present in Africa. Presumably, there must also be some people infected with it in the US.
My question is: why did you exclude subtype E? Is it not a pure subtype? Also, you excluded subtype "I" - is there an I subtype?
One other thing - you pointed out recently that the US ELISA tests are not as good at detecting antibodies to non B subtypes. It would be appreciated if you could mention those tests that are better at detecting all Group M subtypes. With the increase in non B infections in the US, is it not possible to have an HIV test that covers all subtypes so - if one had exposure to a European, African or Latino (or to someone who was themself exposed to someone from one of those places) - one can trust a negative result? While B subtype infection is still the vast majority of infections in the US, many Americans are increasingly exposed to genetic variants through traveling or through exposure to an immigrant (or exposure to someone who had exposure to an infected immigrant or tourist). I think it is a concern if the HIV specialists are not becoming more versed in non B subtypes and if antibody and VL tests are not available to cover all subtypes.
Response from Dr. Pierone
Hello, this field moves extremely fast and the nomenclature for subtype classification was recently updated. Subtype E is now CRF01_AE. This means circulating recombinant form that is a mosaic of subtype A and E. So there is no longer a pure subtype E (or I for that matter).
Newer ELISA tests in the U.S. (and Europe) are now much better at detecting non-B subtypes based on methodological improvements so the issue has been addressed and ongoing refinements are being made. Thus, a negative HIV test result is highly predictive of absence of infection, even for exotic travelers. Additionally, the viral load testing for non-B subtypes is available via a number of different techniques now and newer ones are also much more able to measure levels on non-B virus.
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