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G-C Perng, B Maguen, L Jin, KR Mott, A Yukht, N Osorio, AB Nesburn, C Jones, SL Wechsler; A Novel Herpes Simplex Virus Type 1 (HSV-1) Transcript (AL-RNA) Antisense to the 5' End of LAT (latency associated transcript) Produces a Protein in Infected Rabbits . Invest. Ophthalmol. Vis. Sci. 2002;43(13):881.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Look for a novel gene overlapping the 5' end of LAT (latency associated transcript). LAT, the only known viral gene abundantly transcribed during HSV-1 neuronal latency, is required for high levels of reactivation. Recently we showed that LAT has anti-apoptosis activity (Perng, et. al., 2000, Science, 287:1500-1503; Inman, et. al., 2001, J.Virol. 75:3636-3646) which may be a key to the mechanism by which LAT enhances reactivation. Although LAT null mutants do not have altered virulence, we found that deletions in the 5' end of the primary LAT transcript that do not alter the LAT promoter, can affect viral virulence (Perng, et al, 2001, J.Virol. 75:9018-9028), suggesting the presence of an unknown gene that overlaps the 5' end of LAT. Methods: RT-PCR was used to search for low abundance transcripts overlapping the 5' end of LAT in infected PC-12, RS, and CV-1 cells. Western blots were done using serum from HSV-1 infected rabbits against recombinantly expressed AL protein. Results: A novel, low abundance, HSV-1 RNA (AL-RNA) was found that is antisense to LAT and overlaps the core LAT promoter and the first 158 nucleotides of the 5' end of the primary LAT transcript. The AL-RNA was detected in extracts from HSV-1 infected neuronal derived PC-12 cells, but not in parallel extracts from non-neuronal CV-1 or RS cells. Based on comparison to the corresponding genomic sequence, the AL-RNA did not appear to be spliced. The AL RNA was polyadenylated and contained an open reading frame capable of encoding a protein 56 amino acids in length. Antibody from rabbits infected with wild type HSV-1 but not antibody from rabbits infected with a mutant deleted for the AL-RNA region, recognized the putative AL protein on Western blots. Conclusion: A novel transcript (AL-RNA) that overlaps the 5' end of LAT in an antisense direction is made in neuronal derived cells in tissue culture. A protein encoded by this RNA is made in infected rabbits. The AL protein may be pro-apoptotic, since computer analysis indicated that the first 54 amino acids of AL were similar to a domain found in a mouse apoptosis-associated tyrosine kinase protein and in two putative human proteins also believed to be tyrosine-protein kinases. Interactions between anti-apoptotic LAT and pro-apoptotic AL may play an important role in the latency-reactivation cycle.
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