Known Types
Since its discovery in 1981, Human Immunodeficiency Virus, like many other viruses do evolve and adapt throughout time, which does pose as a problem to modern medicine, because adaptation and evolution of the virus does allow the virus to not only acclimate to the environment but also allows the virus to be more resilient to current antibodies and treatments. Currently there are two types of HIV strains: HIV-1 and HIV-2; where HIV-1 are grouped under M, N, O, and P with a variable number of clades (subgroups); while HIV-2 has no main groups but, has only 8 distinguishable clades (subgroups) (Sharp 2011).
Group M
Lineage M is known as the first pandemic form of HIV-1 discovered in 1891, and is commonly known to be the first and most prevalent virus, where many patients who are diagnosed with HIV-1, has this original lineage M class of HIV-1; and unlike other lineages of HIV, lineage M HIV-1 spans and exists in all countries across the globe. This further allows lineage M HIV-1 to increase its spectrum of genetic diversity; where lineage M HIV-1 has 10 clades (subclasses): A, B, C, D, F, G, H, K, L and CRFs of viruses (Sharp 2011).
Group N
Lineage N is another lineage of HIV-1 that was discovered in 1998, and is not as prevalent as lineage M or O HIV; where lineage N HIV-1 virus is primarily bounded to the country of Cameroon, and only 19 cases of lineage N HIV-1 were ever documented (Sharp 2011).
Group O
Lineage O is another lineage of HIV-1 that was discovered in 1990, and is less prevalent than Lineage M HIV-1; which has only infected 1% of HIV patients in the world, and originates within Cameroon, Gabon, and other Neighbouring countries (Sharp 2011).
Group P
Lineage P is another lineage of HIV-1 that was discovered in 2009, within one individual in the country of Cameroon; and is known to be the least prevalent than lineage N HIV-1 (Sharp 2011).
HIV-2
HIV-2 although a different strain than that of HIV-1, shares the same phylogenetic tree; where HIV-2 is known to be a retroviridae subsumed lentivirus similarly to HIV-1; but the difference among HIV-1 and HIV-2 is that HIV-2 is conceived from a primitive lentivirus. This means that a long time ago before HIV-1 and HIV-2 became prevalent in humans, both species were distinctly known as one strand of HIV, and were prevalent in the simian species; where during one point of time this single HIV strand had bridged out and evolved to create two distinct strands of HIV: HIV-1, and HIV-2; where HIV-2 through much of time, has adapted and developed 8 clades (subclasses): A, B, C, D, E, G, H, and F (Sharp 2011).
