Telomeric expression sites are highly conserved in Trypanosoma brucei.

Subtelomeric regions are often under-represented in genome sequences of eukaryotes. One of the best known examples of the use of telomere proximity for adaptive purposes are the bloodstream expression sites (BESs) of the African trypanosome Trypanosoma brucei. To enhance our understanding of BES structure and function in host adaptation and immune evasion, the BES repertoire from the Lister 427 strain of T.

A soluble factor secreted by an HIV-1-resistant cell line blocks transcription through inactivating the DNA-binding capacity of the NF-kappa B p65/p50 dimer.

The identity and activity of several anti-HIV soluble factor(s) secreted by CD8 and CD4 T lymphocytes have been determined; however, some of them still await definition. We have established an HIV-1-resistant, transformed CD4 T cell line that secretes HIV-1 resistance protein(s). Our studies indicate that this protein(s), called HIV-1 resistance factor (HRF), inhibits transcription of the virus by interfering with the activity of NF-kappaB.

Monoubiquitinated histone H1B is required for antiviral protection in CD4(+)T cells resistant to HIV-1.

Linker histone H1B (H1B) coeluted with an antiviral activity during the purification of HIV-1 resistance factor (HRF) from supernatants of HRF(+) cells. Western blot analysis of the supernatant using alpha-H1 and alpha-ubiquitin antibodies detected the same band of roughly 46 kDa; this band was absent from the control supernatant. Depletion of histone from biologically active material did not affect its potential, suggesting that ubiquitinated H1B is not required for the HRF-mediated antiviral protection in HIV-1 susceptible target cells; however, specific silencing of histone H1B via RNAi in HRF(+) cells reduced the biological activity of cell culture supernatants by 96% and reversed the HIV-1 resistance phenotype of HRF(+) cells.