The herpes simplex virus type 1 (HSV‐1) transcripts that can be detected during latent infection by Northern blot analysis in human and experimental animal sensory ganglia are encoded by diploid genes. To investigate their role in latent infection we studied HSV‐1 variant 1704, which has deleted most of the IRL copy of the coding region of these RNAs and has a 1.2‐kb deletion that is immediately upstream of the coding region of the TRL copy. During primary infection, 1704 replicated in trigeminal ganglia with kinetics similar to the parent virus (17+) and established latent infection. However, while explant reactivation of latent HSV‐1 from trigeminal ganglia was detected in 100% of 17+ infected mice within 7 days, the reactivation of 1704 was significantly delayed, and 31 days elapsed before eight out of nine mice became virus positive. The recognized HSV‐1 latency‐associated RNAs were not detected during the latent state of 1704 by Northern blot analysis or in situ hybridization, which implies that the 1.2‐kb deletion may contain the promoter or other important regulatory elements. The data indicate that detectable levels of these latency‐associated transcripts are not required for viral replication, establishment, or maintenance (greater than 6 weeks) of HSV‐1 latency in trigeminal ganglia, but suggest a role in reactivation.

During herpes simplex virus type 1 (HSV-1) latent infection of the mouse trigeminal ganglion there is limited viral gene expression. The latency-associated transcripts (LAT) map approximately to the PstI-Mlul fragment within the BamHI B and BamHI E fragments (long repeat regions) of the viral genome. Additional weak hybridization signals have been detected by in situ hybridization that correspond to transcription from HSV-I DNA fragments adjacent to the PstI-Mlul fragment. We mapped the region encoding this additional transcription. This minor latency-associated RNA (m-LAT) was shown to map to a group of contiguous fragments (approximately 8-3 kb of DNA), which are adjacent to the 3' end of LAT and to a (2-0 kb) fragment adjacent to the 5' end of the LAT. Using single-stranded probes in in situ hybridization experiments, we showed that the KpnI-BamHI and BamHI-SacI regions of m-LAT are transcribed in a rightward direction within the long internal repeat region. This low abundance RNA may be related to the previously described LAT.

5‐Enol‐pyruvylshikimate‐3‐phosphate synthase from Agrobacterium sp. CP4 (CP4 EPSPS) confers tolerance to the nonselective herbicide glyphosate (marketed under the trade name Roundup1) when sufficiently expressed in transgenic plants. Dual CP4 EPSPS transgene cassettes were transformed into corn (Zea mays L.) under the transcriptional regulatory control of the rice (Oryza sativa L.) actin 1 (P‐Ract1) and the enhanced Cauliflower mosaic virus 35S (P‐e35S) promoters, respectively, to impart fully constitutive expression in corn. Resulting events were tested for lack of chlorosis and malformation injury after two sequential applications of 1.68 kg acid equivalents (a.e.) ha−1 glyphosate. Agronomic parameters, male fertility, appropriate Mendelian segregation of the trait, plus characteristics of the transgenic integration site were also evaluated. From this selection process, the NK603 event was chosen for commercialization as the event that embodied the most optimal profile of tolerance, agronomics, and molecular characteristics. The NK603 event exhibited high glyphosate tolerance from one transgenic locus bearing a single copy of the dual cassettes integrated into the corn genome with a minimum of target sequence disruption. Trait expression in the NK603 event has remained stable over more than eight generations as shown through tolerance testing, western blots of CP4 EPSPS accumulation, and Southern blot analysis of the transgene.

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The herpes simplex virus type 1 (HSV-1) latency-associated transcripts (LATs) accumulate in neuronal nuclei of latently infected ganglia. Explant reactivation kinetics of LAT deletion mutants in the mouse eye model have suggested a role for the LATs in the reactivation process. This report describes the construction and characterization of an HSV-1 strain HFEM mutant, TB1, disrupted within both copies of the LAT gene. TB1 contains a 440-base-pair segment of bacteriophage lambda DNA in place of a 168-base-pair deletion within the transcribed portion of the LAT gene. The 2.0-kilobase LAT was not produced after infection of tissue culture cells with TB1, but a 0.7to 0.8-kilobase RNA was expressed. TB1 did establish latent infection after corneal inoculation as efficiently as the parental virus, and its reactivation kinetics from explanted ganglia were similar to those of HFEM. During latent infection with TB1, HSV-1 transcripts were not detectable. Rescuant virus (TB1-R) contained intact LAT genes, synthesized full-length LAT transcripts during productive infection in tissue culture, and reactivated from ganglionic explants of latently infected mice with normal kinetics. Thus, any function these transcripts have in the reactivation process appears to include the region between the putative LAT promoter and the disruption in TB1-a region of approximately 1,600 nucleotides, 800 of which encode the LATs.