Inhibition of Herpes Simplex Virus Reactivation by Dipyridamole

Abstract

Herpes simplex virus (HSV) reactivation from latency was investigated. Reactivation of thymidine kinasenegative HSV, which is defective for reactivation, was greatly enhanced by thymidine (TdR). The reactivationenhancing effect of TdR was blocked by dipyridamole (DPM), a known nucleoside transport inhibitor. DPM also inhibited wild-type HSV reactivation, suggesting potential antiviral use.In experimental models of herpes simplex virus (HSV) infection, expression of viral thymidine kinase (TK) has been shown to be important for viral latency. This was first suggested in studies of mice infected with TK-negative HSV. It was shown that in cases of acute infection, HSV replicated well in ocular tissues but not in trigeminal ganglia (TG) and that HSV reactivated poorly in ganglia during latency. Subsequently it was shown that establishment of latency was intact, i.e., latency-associated transcript (LAT) was readily detected in ganglion neurons, but reactivation was impaired (4, 5, 16). The defect of reactivation was explored in studies which showed that TKnegative HSV could in fact readily reactivate in ganglia if explant medium was supplemented with thymidine (TdR) (17). The present study extended this observation in three ways. First, it was shown that if a nucleoside transport inhibitor is added along with supplemental TdR, the effect of TdR on enhancing TK-negative HSV reactivation is blocked. This suggests the specific roles of TdR and phosphorylation by TK in the reactivation process. Second, it is shown that the nucleoside transport inhibitor also blocks wild-type HSV reactivation from latency. Lastly, supplemental TdR decreased the dipyridamole (DPM) block of wild-type HSV reactivation.Latent infection of TG and lumbar dorsal root ganglia (DRG) was established in randomly bred CD-1 mice (Charles River Laboratories, Wilmington, Mass.) by standard methods. In brief, mice were anesthetized (methoxyflurane), and corneal inoculation (5 l) or footpad inoculation (25 l) was performed (17). Inoculation was performed with either TK-positive wild-type HSV type 1 (HSV-1; strain KOS, 5 ϫ 10 8 PFU/ ml) or with mutant TK-negative HSV-1 (dlsactk, 4 ϫ 10 8 PFU/ml). The titers of the viruses were determined on Vero cells using standard methods. The KOS virus had been used previously (16,17). It readily established latency (i.e., LAT expression) and reactivated from latency in explants with a frequency of 90 to 100%. The dlsactk mutant strain was kindly provided by D. Coen (Harvard Medical School, Boston, Mass.). It was shown to express less than 1% of parental TK activity (4, 7). LAT expression during latency in mice inoculated with dlsactk was similar to that in mice with the TKpositive KOS strain, but reactivation from latency occurred at a frequency of 0 to 10% (4,7,17).After 28 to 30 days, mice were anesthetized (methoxyflurane) and exsanguinated by cardiac puncture. HSV inoculation of mice, as well as housing and eventual sacrifice, were done in accordance with institutional and federal guidelines. TG and DRG (from lumb...

Dipyridamole Reversibly Inhibits Mengovirus RNA Replication

“…Dipyridamole is very effective at inhibiting nucleoside transport into cells, and this is the presumed mechanism for its medical efficacy. Its activity was also evaluated for other applications, including use as an inhibitor of herpes simplex virus reactivation (33) and as a potentiator of the antiviral effects of 3Јazido-3Јdeoxythymidine against human immunodeficiency virus (22 even when administered in the absence of 3Јazido-3Јdeoxythy-midine (22). Our mengovirus studies found dipyridamole to be equally effective in infected cells and in vitro replication reactions where nucleoside uptake was not an issue.…”

Pyrimidinthiones (Part I): Utility of 2-Thioxopyrimidin-6-(1H)ones as Ring Transformer in the Synthesis of Fused Bi- and Tri-Cyclic Heterocyclic Compounds and Their Potential Biological Activities

“…The products of alkylation of (1a,c) with α-haloacid and/or α-halo-ester such as mono-chloroacetic acid is dependent upon the reaction conditions 30 ; if the reaction is carried out in refluxing ethanol/piperidine and/or dry acetone/anhydrous potassium carbonate, the isolated products are 4-aryl-5-cyanopyrimidin-6(1H)-one-2-thioglycollic acid derivatives (9a,b), while if it done in DMF and ethanolic NaOH (10%), the products are identified as the bicyclic Downloaded by [McGill University Library] at 01:07 11 October 2012 system 6-cyano-7-aryl [1,3]thiazolo[3,2-a]pyrimidin-3,5-dione derivatives (10a,b), which are obtained also on treatment of (9a,d) with a refluxing mixture of glacial acetic acid-anhydrous AcONa. On the other hand treatment of the title compounds (1a,c) with chloroacetyl chloride 9 as bi-functional halo-organic compound in DMF afforded the same products 10a,b.…”

“…Alkylation of 1a with α-haloketones such as mono-bromoacetone 8 depends upon the reaction conditions and the used base; if the reaction is carried out in refluxing ethanol and piperidine, the obtained products are 2-substituted thio-4-(3,4-methylenedioxyphenyl)-5-cyanopyrimidin-6(1H)-ones (7), while if it done in DMF and ethanolic NaOH (10%) it yielded 3-substituted 6-cyano-7-(3,4-methylenedioxyphenyl)- [1,3]thiazolo[3,2-a]pyrimidine-5-ones (8), also compounds (7) underwent cyclization by refluxing with a mixture of acetic anhydride/pyridine (1:1) to afford (8).…”

Easy synthesis of new series of pteridine analogs: di- and tetra-hydropyrimido[4,5-d]pyrimidines via 5-pyrimidinecarbaldehydes

“…On account of the pharmaceutical interest in these compounds, the development of highthroughput methodologies for the synthesis of novel pyrimidine-fused heterocyclic scaffolds is in continuous expansion. [15][16][17][18][19] It has become widely accepted that many classical reactions perform better under microwave irradiation than by conventional heating methods. [20][21][22][23][24] Microwave irradiation has been used to carry out a wide range of reactions in short times, with high yields and regioselectivity, and frequently without the need of solvents.…”