Inhibition of human cytomegalovirus in culture by alkenyl guanine analogs of the thiazolo[4,5-d]pyrimidine ring system

Abstract

A series of alkyl and alkenyl guanine analogs containing a thiazolo [4,5-d]pyrimidine ring system were prepared by reaction of the appropriate alkyl halide with the sodium salt of the heterocycle. In preliminary antiviral efficacy evaluations against laboratory strains of both human cytomegalovirus (HCMV) and herpes simplex virus types 1 and 2, it was determined that two of the compounds (T70072 and T01132) were more active and less toxic in stationary-phase cell monolayers than were the other derivatives tested. T01132 and T70072, which have 2-pentenyl and 3-methyl-2-butenyl moieties attached to position 3 of the 5-aminothiazolo[4,5-dlpyrimidine-2,7-dione, respectively, were then more extensively evaluated for anti-HCMV activity.The concentrations of T01132 and T70072 required to inhibit HCMV by 50%o in plaque reduction assays were -0.5 and 6.8 ,iM, respectively. These two compounds inhibited the growth of KB, or Vero cells at concentrations of 75 to 150 ,uM, depending upon the cell line. In bone marrow progenitor cells T01132 was slightly less toxic than ganciclovir (DHPG). The 50%o inhibitory concentrations of T01132 against clinical isolates and DHPG-resistant strains of HCMV were approximately the same as those obtained for laboratory strains of HCMV (-0.5 jiM). When tested in combination with DHPG, the resultant antiviral activity was determined to be additive but not synergistic. Experiments performed using variations of the viral multiplicity of infection (MOI) demonstrated that T01132 was more active than DHPG at a low MOI (0.002 or 0.02). However, when a higher MOI (0.2 or 2.0) was used, DHPG was more efficacious than T01132. In experiments in which drug was added at various times post-viral infection, T01132 was most effective when added within the first 24 h post-HCMV infection while DHPG was able to protect cells in this assay system when added up to 48 h postinfection, indicating that T01132 is exerting its antiviral effect on events leading up to and possibly including viral DNA synthesis. The data presented in this report suggest that the antiviral activity of alkenyl-substituted thiazolopyrimidine derivatives may represent a mechanism of action against herpesviruses alternative to that of classical nucleoside analogs such as acyclovir or DHPG.

The 6-Aminoquinolone WC5 Inhibits Human Cytomegalovirus Replication at an Early Stage by Interfering with the Transactivating Activity of Viral Immediate-Early 2 Protein

“…To (Table 2), as determined by paired t tests (P, Ն0.05). This result is in agreement with previous observations that GCV does not act in an MOI-dependent manner (17,36). In contrast, there were significant differences among the EC 90 s of WC5 at all MOIs tested (Table 2), with the greatest difference between the EC 90 s of WC5 at MOIs of 1 and 0.01 PFU/cell (P, 0.005), as expected.…”

“…Thus, to investigate whether WC5 might inhibit the HCMV DNA polymerase through a mechanism different from that of GCV, CDV, ACV, and FOS, we tested the effects of the compound on the activity of the viral enzyme in vitro. The enzyme activity in the presence of serial dilutions of WC5 or of FOS as a control was evaluated by measuring the incorporation of [ 3 H]dTTP into a poly(dA)-oligo(dT) [12][13][14][15][16][17][18] template-primer by a purified, baculovirus-expressed DNA polymerase catalytic subunit (UL54) both in the absence and in the presence of the accessory subunit (UL44). As expected, FOS inhibited the DNA polymerase activities of both UL54 alone and the UL54/UL44 complex in a dosedependent manner, with 50% inhibitory concentrations (IC 50 s) of 3.1 M and 5.5 M, respectively (Fig.…”

T30177, an oligonucleotide stabilized by an intramolecular guanosine octet, is a potent inhibitor of laboratory strains and clinical isolates of human immunodeficiency virus type 1

“…Respiratory syncytial virus (strain A2) and influenza virus A (strain H3N2) assays were performed as described by Wyde et al (43), while herpes simplex virus type 1 and 2 plaque reduction assays were performed as described previously (25). Vesicular stomatitis virus, vaccinia virus, Sindbis virus, coxsackievirus B4, poliovirus type 1, and Semliki forest virus assays were performed as described by De Clercq (13).…”

Artemisinin-Derived Dimer Diphenyl Phosphate Is an Irreversible Inhibitor of Human Cytomegalovirus Replication

“…CMV-infected cells require a short exposure to 838, but in the case of AS, a longer exposure may be required for effective CMV inhibition. To further support the early CMV inhibition by AS and 838, their activities were assayed at different MOIs (MOI dependency) (15,22). Virus yields in supernatants collected at 6 days postinfection from HFF cells infected with CMV at MOIs of 0.05, 1, and 5 were quantified by real-time PCR.…”