Herpes simplex virus type 1 (HSV-1) and HSV-2 cause very similar acute infections but differ in their abilities to reactivate from trigeminal and dorsal root ganglia. To investigate differences in patterns of viral infection, we colabeled murine sensory ganglia for evidence of HSV infection and for the sensory neuron marker A5 or KH10. During acute infection, 7 to 10% of HSV-1 or HSV-2 antigen-...

The latency-associated transcript (LAT) is the only herpes simplex virus (HSV) gene product detectable in latently infected humans and animals. In this report, we show that a 624-bp deletion in the promoter of the HSV-2 LAT had no discernable effect on viral growth in tissue culture or in acute genital infection of guinea pigs, but impaired LAT accumulation and led to a marked decrease in spont...

RNA transfer (Northern) blot analysis was used to perform the physical characterization of the transcript expressed in murine sensory nerve ganglia latently infected with herpes simplex virus type 1. Most of this latency-associated transcript (LAT) was isolated in the poly(A)- fraction from ganglia. A smaller RNA species was also detected at less than 10% the abundance of the major one. LAT was...

Herpes simplex virus type 1 (HSV-1) is the leading cause of virus-induced encephalitis; however, the viral genes that regulate encephalitis have not been well characterized. In this study, we tested whether the LAT (latency-associated transcript) locus regulates the frequency of encephalitis in male or female mice. Male BALB/c mice are more susceptible to HSV-1-induced encephalitis than age-mat...

Herpes simplex virus (HSV) latency in sensory ganglion neurons is well documented, but the existence of extraneuronal corneal latency is less well defined. To investigate the possibility of extraneuronal latency during ocular HSV infection, corneal specimens from 18 patients with quiescent herpes simplex keratitis (HSK) were obtained at the time of keratoplasty. Polymerase chain reaction (PCR) ...

During latent infection by herpes simplex virus (HSV), an abundant latency-associated transcript (LAT) that is antisense to a predominant viral alpha gene (ICP0) is found localized in the nucleus of sensory neurons. We disrupted both copies of the LAT gene in the HSV-1 genome by insertion of the Escherichia coli lacZ gene under LAT promoter control. The resulting recombinant virus, RH142, does ...

Herpes simplex virus 1 (HSV-1) unspliced 8.3 latency associated transcript (LAT), which located in the long repeat sequences, has been shown to contain at least 16 open reading frames (ORF: A-P). One of these ORF, ORF P, maps almost entirely antisense to HSV-1 neurovirulence gene, ICP34.5. Both ORF P and ICP34.5 are located in the long repeat and are antisense overlapping genes. Therefore, in O...

To better understand the mechanisms responsible for the observed effects of deletions in the promoter region of the latency-associated transcript (LAT) gene in impairing herpes simplex virus (HSV) reactivation, we generated mice transgenic for a 5.5-kb HSV type 2 (HSV-2) genomic fragment spanning the major LAT, along with the LAT promoter and flanking regions, in the C57BL/6 background. The mic...

Dorsal root ganglion neurons, which express herpes simplex virus (HSV) latency-associated transcript (LAT) during experimental latent infection, were investigated by in situ hybridization. The number of LAT-positive neurons was determined by examination of ganglion serial sections. In other latently infected mice, the number of ganglion neurons that reactivated HSV antigen after explant culture...

Herpes simplex virus type 1 establishes latent infections in sensory neurons. During latency only one locus, the latency-associated transcript (LAT), is abundantly transcribed. Several lines of evidence suggest that this locus is required for the efficient reactivation from latency in experimental models. However, it is not yet clear whether this is a direct effect on the reactivation process p...