|
| Tax | HBZ |
|
| Naturally occurring genetic and epigenetic changes in ATLL | | |
|
| Point mutations | Detected in Tax 11–19 A*0201 epitope [25] | None described |
|
| Deletions | Premature stop codons [26] | None described |
| Deletions of 5′end of genome [25, 27, 28] | |
|
| Epigenetic silencing | Hypermethylation of 5′LTR [46, 59, 60] and pX region [59] | None described |
|
| Expression in ATLL | | |
|
| In vivo | mRNA and protein low/undetectable [45, 46] | Multiply spliced isoforms of mRNA detected [51, 52] |
|
| Ex vivo cultures | Increased mRNA transcription in vitro culture [54] | Increased mRNA transcription after culture in vitro [54] |
| Protein detected in 50% of ATL cases [44] | Protein at threshold for detection using currently available antibodies [53] |
|
| CTL response in AC and HAM/TSP | | |
|
| CTL response in vivo | High frequencies Tax-specific CTL detected in 66–94% infected individuals [12, 15, 43] | Low frequencies of HBZ-specific CTL detectable in 25–40% of individuals [42, 43] |
|
| Immunogenicity for CTL | Immunodominant, HTLV-1 protein most frequently recognized by CTL [12–14] | Peptides bind weakly to HLA class-1 in general [42]
Highly sensitive, cytotoxic CTL which recognise HBZ 26–34 in the context of A*0201 can be generated in vitro [53] |
|
| Potential for protection in ATLL | Enhanced ability to present Tax peptides does not confer a significant protective effect [42] but can lyse ATL cells expressing Tax in vitro [23, 24] | Efficient presentation of HBZ peptides significantly associated with low PVL and remaining asymptomatic [42] |
|
