Author:

Keywords:

Evolution, Genome, Viral, HTLV-II Infections, Human T-lymphotropic virus 2, Humans, Substance Abuse, Intravenous, Variation (Genetics), Virus Replication, Science & Technology, Life Sciences & Biomedicine, Genetics & Heredity, Amerindians, clonal expansion, evolution, genomic stability, HTLV-II, injecting drug users (IDUs), origin, INJECTING DRUG-USERS, COMPLETE NUCLEOTIDE-SEQUENCE, LEUKEMIA-LYMPHOMA VIRUS, LENGTH-POLYMORPHISM ANALYSIS, POLYMERASE CHAIN-REACTION, HIGH PROVIRAL LOAD, CLONAL EXPANSION, AFRICAN ORIGIN, MOLECULAR CHARACTERIZATION, ENVELOPE SEQUENCE, Biological Evolution, Genetic Variation, 0604 Genetics, 0606 Physiology, 1108 Medical Microbiology, Developmental Biology, 3101 Biochemistry and cell biology, 3102 Bioinformatics and computational biology, 3105 Genetics

Abstract:

In this review, the origin and evolution of the human T-cell lymphotropic virus type II (HTLV-II) are discussed, with particular emphasis on its high genomic stability. In particular, it appears that the virus originated in the African continent and has been infecting human populations for several thousands of years. The very low divergence accumulated on average between different viral strains during such a long period could be explained by considering that in infected individuals the viral amplification could be due mainly to the clonal expansion of the infected cells, via cellular mitosis, rather than to reverse transcription. HTLV-II was introduced into the American continent during one or more migrations of HTLV-II-infected Asian populations over the Bering land bridge, some 15,000-35,000 years ago. Finally, during the last few decades, HTLV-II has been transmitted from native Amerindians to injecting drug users (IDUs). It might be speculated that at least two separate introductions of HTLV-II in European IDUs from US IDUs have occurred, due to the practice of needle-sharing among IDUs.