We recently demonstrated that CD8؉ T cells could block herpes simplex virus type 1 (HSV-1) reactivation from latency in ex vivo trigeminal ganglion (TG) cultures without destroying the infected neurons. Here we establish that CD8؉ T-cell prevention of HSV-1 reactivation from latency is mediated at least in part by gamma interferon (IFN-␥). We demonstrate that IFN-␥ was produced in ex vivo cultures of dissociated latently infected TG by CD8 ؉ T cells that were present in the TG at the time of excision. Depletion of CD8 ؉ T cells or neutralization of IFN-␥ significantly enhanced the rate of HSV-1 reactivation from latency in TG cultures. When TG cultures were treated with acyclovir for 4 days to insure uniform latency, supplementation with recombinant IFN-␥ blocked HSV-1 reactivation in 80% of cultures when endogenous CD8 ؉ T cells were present and significantly reduced and delayed HSV-1 reactivation when CD8 ؉ T cells or CD45 ؉ cells were depleted from the TG cultures. The effectiveness of recombinant IFN-␥ in blocking HSV-1 reactivation was lost when its addition to TG cultures was delayed by more than 24 h after acyclovir removal. We propose that when the intrinsic ability of neurons to inhibit HSV-1 gene expression is compromised, HSV-specific CD8 ؉ T cells are rapidly mobilized to produce IFN-␥ and perhaps other antiviral cytokines that block the viral replication cycle and maintain the viral genome in a latent state.Following primary infection of epithelial surfaces, herpes simplex virus type 1 (HSV-1) gains access to the termini of sensory neurons, is transported in a retrograde direction to the neuron cell bodies in sensory ganglia, replicates, spreads to other neurons, and establishes a lifelong latent infection in a portion of the neurons. Recurrent HSV-1 disease results from reactivation of latent HSV-1 in sensory neurons followed by anterograde axonal transport to epithelial or epidermal surfaces. Therefore, treatments that block reactivation of HSV-1 from latency could effectively prevent recurrent disease in the face of latent infection. The long-term retention of CD8 ϩ T cells and production of the cytokine gamma interferon (IFN-␥) in the latently infected trigeminal ganglion (TG) suggest a possible role for the immune system in controlling HSV-1 reactivation from latency (4,10,16,20).Ganglionic latency is classically defined as retention of HSV-1 genomes in neurons in the absence of virion production. The definition of latency at the molecular level is currently evolving. Clearly, a family of transcripts called latencyassociated transcripts is produced in abundance in at least a portion of latently infected neurons (6, 7). In addition, transcripts for the HSV-1 ␣ (immediate-early) gene, infected cell protein 4 (ICP4), and ␤ (early) gene thymidine kinase were detected in low abundance in latently infected murine sensory ganglia (13). Most studies have failed to detect latency-associated transcript translation products, and the production of any viral proteins in latently infected neurons is currentl...

The larvicidal activity and repellency of 5 plant essential oils-thyme oil, catnip oil, amyris oil, eucalyptus oil, and cinnamon oil-were tested against 3 mosquito species: Aedes albopictus, Ae. aegypti, and Culex pipiens pallens. Larvicidal activity of these essentials oils was evaluated in the laboratory against 4th instars of each of the 3 mosquito species, and amyris oil demonstrated the greatest inhibitory effect with LC 50 values in 24 h of 58 µg/ml (LC 90 = 72 µg/ml) for Ae. aegypti, 78 µg/ml (LC 90 = 130 µg/ml) for Ae. albopictus, and 77 µg/ml (LC 90 = 123 µg/ml) for Cx. p. pallens. The topical repellency of these selected essential oils and deet against laboratory-reared female blood-starved Ae. albopictus was examined. Catnip oil seemed to be the most effective and provided 6-h protection at both concentrations tested (23 and 468 µg/cm 2). Thyme oil had the highest effectiveness in repelling this species, but the repellency duration was only 2 h. The applications using these natural product essential oils in mosquito control are discussed. Entomology Comments This article is from

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