Overlapping subdeletions within a 348-bp in the 5' exon of the LAT region that facilitates epinephrine-induced reactivation of HSV-1 in the rabbit ocular model do not further define a functional element.
A previous study identified a 348-bp region at the 5' end of the 8.5-kb latency-associated transcript (LAT) of HSV-1 strain 17Syn+ that is necessary for maximum adrenergically induced reactivation following transcorneal iontophoresis of epinephrine (D.C. Bloom et al., 1996, J. Virol. 70, 2449-2459). In that study, the construct with complete deletion of the 348-bp region, 17delta348, failed to achieve the high reactivation frequency demonstrated by the parent (17Syn+) and rescued (17delta348R) viruses. To further characterize the function of the 348-bp region, we analyzed two genetic constructs with partial deletions in the same 348-bp region, 17delta201 and 17delta207, in the rabbit model. Both constructs exhibited the same high reactivation frequencies demonstrated by the parent 17Syn+ and the rescued 17delta348R viruses. These results suggest that the control of reactivation is distributed over a large portion of the 348-bp region, rather than being confined within a smaller, more discrete region. To assess whether the low reactivation phenotype of the 17delta348 construct was caused by a requirement for proper spacing of elements outside the 348-bp region, we constructed a virus (17delta348St) that contained a 360-bp stuffer fragment of heterologous DNA (lacZ) to maintain the proper spacing. The 17delta348St construct also displayed a low reactivation phenotype, similar to that of 17delta348, suggesting that the effect of deleting this segment of the 5' exon of LAT is obtained through a mechanism other than the disruption of spacing.
Bhattacharjee
Partha S
PS
LSU Eye Center, Department of Ophthalmology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA.
Tran
Robert K
RK
Myles
Marvin E
ME
Maruyama
Koichi
K
Mallakin
Ali
A
Bloom
David C
DC
Hill
James M
JM
D000818:Animals; D004195:Disease Models, Animal; D004837:Epinephrine / Q000494:pharmacology*; D005091:Exons / Q000235:genetics*; D005814:Genes, Viral / Q000235:genetics; D006561:Herpes Simplex / Q000821:virology; D016849:Keratitis, Herpetic / Q000821:virology; D011817:Rabbits; D017384:Sequence Deletion / Q000235:genetics*; D018139:Simplexvirus / Q000187:drug effects* / Q000235:genetics* / Q000502:physiology; D014775:Virus Activation / Q000187:drug effects*; D017735:Virus Latency / Q000187:drug effects* / Q000235:genetics*
D004837:Epinephrine