What is the difference between HIV-1 and HIV-2?
There are two types of HIV: HIV-1 and HIV-2. Both types are transmitted by sexual contact, through blood, and from mother to child, and they appear to cause clinically indistinguishable AIDS. However, it seems that HIV-2 is less easily transmitted, and the period between initial infection and illness is longer in the case of HIV-2.
Worldwide, the predominant virus is HIV-1, and generally when people refer to HIV without specifying the type of virus they will be referring to HIV-1. The relatively uncommon HIV-2 type is concentrated in West Africa and is rarely found elsewhere.
How many subtypes of HIV-1 are there?
The strains of HIV-1 can be classified into four groups: the “major” group M, the “outlier” group O and two new groups, N and P. These four groups may represent four separate introductions of simian immunodeficiency virus into humans.
What are the different levels of HIV classification?
Group O appears to be restricted to west-central Africa and group N, a strain discovered in 1998 in Cameroon is extremely rare. In 2009 a new strain closely relating to gorilla simian immunodeficiency virus was discovered in a Cameroonian woman. It was designated HIV-1 group P. More than 90 percent of HIV-1 infections belong to HIV-1 group M. Within group M there are known to be at least nine genetically distinct subtypes of HIV-1. These are subtypes A, B, C, D, F, G, H, J and K.
http://rhesusnegativebloodgroup.com/genetic-traits-resistant-to-hivaids/