[Growing divergence inside primate T cell lymphotropic viruses]

Area of Science:

• * Virology: Characterization of novel simian T-lymphotropic viruses (PTLVs).
• * Evolutionary Biology: Tracing the evolutionary history and divergence of PTLVs.
• * Genetics: Genomic sequencing and phylogenetic analysis of primate retroviruses.

Context:

• * Primate T-lymphotropic viruses (PTLVs) are closely related to human T-lymphotropic viruses (HTLVs).
• * Previous research established well-defined lineages of PTLVs.
• * Understanding PTLV diversity is crucial for studying retroviral evolution and zoonotic potential.

Purpose:

• * To isolate and genomically characterize novel, divergent simian T-lymphotropic viruses (PTLVs).
• * To determine the evolutionary relationship of these new viruses to known HTLV-I and HTLV-II.
• * To investigate the genomic organization and potential protein expression of these novel PTLVs.

Summary:

• * Two distinct PTLVs, STLV-PH969 (from baboon) and STLV-PP1664 (from bonobo), were isolated and sequenced.
• * Phylogenetic analysis indicates STLV-PH969 is equidistant from HTLV-I and HTLV-II, suggesting ancient separation.
• * STLV-PP1664 is highly divergent from known HTLV-II subtypes, with unique pX region organization and splicing patterns.
• * Both viruses possess common open reading frames but exhibit distinct viral messenger and protein expression compared to HTLV-I and HTLV-II.

Impact:

• * Establishes a new PTLV type (PTLV-L) and identifies a divergent STLV-II subtype.
• * Highlights the genetic diversity of PTLVs in non-human primates.
• * Underscores the importance of studying PTLV prevalence and interspecies transmission, particularly in the context of xenotransplantation.