HTLV-III and HTLV-IV
When HIV, the virus that causes AIDS, was characterized in 1984 by Robert Gallo, he named it HTLV-III. HTLV-III is currently the name used to describe another virus related to HTLV-I and HTLV-II. "HTLV-IV" has been used to describe recently characterized viruses.
These viruses were discovered in 2005 in rural Cameroon, and were, it is presumed, transmitted from monkeys to hunters of monkeys through bites and scratches.
- HTLV-III is similar to STLV-III (Simian T-lymphotropic virus 3). Multiple strains have been identified. It expresses gag, pol, and env, among other proteins.
- HTLV-IV does not resemble any known virus.
It is not yet known how much further transmission has occurred among humans, or whether the viruses can cause disease.
The use of these names can cause some confusion, because the name HTLV-III was one of the names for HIV in early AIDS literature, but has since fallen out of use. The name HTLV-IV has also been used to describe HIV-2. A large Canadian study documented this confusion among healthcare workers, where >90% of HTLV tests ordered by physicians were actually intended to be HIV tests.
Read more about this topic: Human T-lymphotropic Virus