Genetic heterogeneity in human T-cell leukemia/lymphoma virus type II

Area of Science:

• Virology
• Molecular Biology
• Genetics

Background:

• Human T-cell lymphoma/leukemia virus type II (HTLV-II) is a retrovirus with a complex evolutionary history.
• Understanding the genetic diversity of HTLV-II is crucial for tracing its origins and spread.
• Previous studies have suggested genetic variations within HTLV-II, but detailed substrain analysis was limited.

Purpose of the Study:

• To investigate the genetic diversity and phylogenetic relationships of HTLV-II strains in the Western Hemisphere.
• To identify distinct genetic substrains of HTLV-II.
• To compare the diversity of HTLV-II with other primate T-cell lymphoma viruses (PTLV).

Main Methods:

• DNA amplification from peripheral blood mononuclear cells of 17 HTLV-II infected individuals using polymerase chain reaction (PCR) with conserved primer pairs (SK110/SK111).
• Cloning and sequencing of a 140-bp fragment from the pol gene of amplified HTLV-II DNA.
• Phylogenetic comparisons and confirmation with additional primer pair-probe sets across the PTLV genome.

Main Results:

• At least two distinct genetic substrains of HTLV-II were identified in the Western Hemisphere.
• HTLV-II isolates from Seminole, Guaymi, and Tobas Indians formed a new substrain, distinct from the prototype MoT isolate.
• HTLV-II New World strains exhibited greater genetic diversity than HTLV-I New World strains, comparable to global PTLV diversity.

Conclusions:

• The findings suggest that HTLV-II may have a long history in indigenous Amerindian populations or was introduced with high initial genetic heterogeneity.
• The identified genetic substrains provide insights into the evolutionary dynamics of HTLV-II in the Americas.
• Further research is warranted to elucidate the precise origins and transmission patterns of HTLV-II substrains.