Heterotypic and homotypic re-inoculation of mice already latently infected with herpes simplex virus type 1

1990 ◽  
Vol 110 (1-2) ◽  
pp. 25-36 ◽  
Author(s):  
D. L. Yirrell ◽  
W. A. Blyth ◽  
T. J. Hill ◽  
C. E. Rogers
1998 ◽  
Vol 42 (7) ◽  
pp. 1555-1562 ◽  
Author(s):  
Alana M. Thackray ◽  
Hugh J. Field

ABSTRACT Famciclovir (FCV) and valaciclovir (VACV) have previously been shown to be potent inhibitors of herpes simplex virus type 1 (HSV-1) in a murine cutaneous model. In the present study, mice were inoculated in the skin of the left ear pinna with herpes simplex virus (HSV) type 1. Antiviral therapy was started on different days postinoculation (p.i.), terminating at the end of day 10 p.i. The compounds were administered twice daily by oral gavage at 50 mg/kg of body weight/dose. Mice were sampled on day 5 p.i., during the acute phase of the infection, and the titers of infectious virus in the target tissues (ear, brain stem, and trigeminal ganglia) were determined. At 2 to 3 months p.i., the ipsilateral and contralateral trigeminal and cervical dorsal root ganglia were explanted, and four different methods were used to detect latent HSV. The methods were (i) conventional explant culture for 5 days followed by homogenization, (ii) long-term culture (up to 73 days) of whole ganglia, followed by homogenization, (iii) dissociation by enzymatic disaggregation and an infectious center assay, and (iv) in situ hybridization to detect latency-associated transcripts (LATs). The conventional explant culture method was the least sensitive method, while in situ staining for LAT was the most sensitive, and all mice, including those treated from early times with FCV, were shown to be latently infected. Significantly less latent virus was detected by all four methods, however, in ganglia obtained from mice that had been treated with FCV in comparison with the amount detected in ganglia from mice that had been treated with VACV. However, in no case was latency completely eliminated.


2000 ◽  
Vol 74 (4) ◽  
pp. 1885-1891 ◽  
Author(s):  
Guey-Chuen Perng ◽  
Susan M. Slanina ◽  
Ada Yukht ◽  
Homayon Ghiasi ◽  
Anthony B. Nesburn ◽  
...  

ABSTRACT The latency-associated transcript (LAT) gene the only herpes simplex virus type 1 (HSV-1) gene abundantly transcribed during neuronal latency, is essential for efficient in vivo reactivation. Whether LAT increases reactivation by a direct effect on the reactivation process or whether it does so by increasing the establishment of latency, thereby making more latently infected neurons available for reactivation, is unclear. In mice, LAT-negative mutants appear to establish latency in fewer neurons than does wild-type HSV-1. However, this has not been confirmed in the rabbit, and the role of LAT in the establishment of latency remains controversial. To pursue this question, we inserted the gene for the enhanced green fluorescent protein (EGFP) under control of the LAT promoter in a LAT-negative virus (ΔLAT-EGFP) and in a LAT-positive virus (LAT-EGFP). Sixty days after ocular infection, trigeminal ganglia (TG) were removed from the latently infected rabbits, sectioned, and examined by fluorescence microscopy. EGFP was detected in significantly more LAT-EGFP-infected neurons than ΔLAT-EGFP-infected neurons (4.9% versus 2%, P < 0.0001). The percentages of EGFP-positive neurons per TG ranged from 0 to 4.6 for ΔLAT-EGFP and from 2.5 to 11.1 for LAT-EGFP (P = 0.003). Thus, LAT appeared to increase neuronal latency in rabbit TG by an average of two- to threefold. These results suggest that LAT enhances the establishment of latency in rabbits and that this may be one of the mechanisms by which LAT enhances spontaneous reactivation. These results do not rule out additional LAT functions that may be involved in maintenance of latency and/or reactivation from latency.


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