RESUMEN
Several benzimidazole nucleoside analogs, including 1H-ß-D-ribofuranosyl-2-bromo-5,6-dichlorobenzimidazole (BDCRB) and 1H-ß-L-ribofuranosyl-2-isopropylamino-5,6-dichlorobenzimidazole (maribavir [MBV]), inhibit the replication of human cytomegalovirus. Neither analog inhibited the related betaherpesvirus human herpesvirus 6 (HHV-6). Additional analogs of these compounds were evaluated against both variants of HHV-6, and two L-analogs of BDCRB had good antiviral activity against HHV-6A, as well as more modest inhibition of HHV-6B replication.
Asunto(s)
Antivirales/farmacología , Bencimidazoles/farmacología , Herpesvirus Humano 6/efectos de los fármacos , Antivirales/química , Bencimidazoles/química , Citomegalovirus/efectos de los fármacos , Humanos , Replicación Viral/efectos de los fármacosRESUMEN
A series of 4'-thionucleosides were synthesized and evaluated for activities against orthopoxviruses and herpesviruses. We reported previously that one analog, 5-iodo-4'-thio-2'-deoxyuridine (4'-thioIDU), exhibits good activity both in vitro and in vivo against two orthopoxviruses. This compound also has good activity in cell culture against many of the herpesviruses. It inhibited the replication of herpes simplex virus type 1 (HSV-1), HSV-2, and varicella-zoster virus with 50% effective concentrations (EC(50)s) of 0.1, 0.5, and 2 microM, respectively. It also inhibited the replication of human cytomegalovirus (HCMV) with an EC(50) of 5.9 microM but did not selectively inhibit Epstein-Barr virus, human herpesvirus 6, or human herpesvirus 8. While acyclovir-resistant strains of HSV-1 and HSV-2 were comparatively resistant to 4'-thioIDU, it retained modest activity (EC(50)s of 4 to 12 microM) against these strains. Some ganciclovir-resistant strains of HCMV also exhibited reduced susceptibilities to the compound, which appeared to be related to the specific mutations in the DNA polymerase, consistent with the observed incorporation of the compound into viral DNA. The activity of 4'-thioIDU was also evaluated using mice infected intranasally with the MS strain of HSV-2. Although there was no decrease in final mortality rates, the mean length of survival after inoculation increased significantly (P < 0.05) for all animals receiving 4'-thioIDU. The findings from the studies presented here suggest that 4'-thioIDU is a good inhibitor of some herpesviruses, as well as orthopoxviruses, and this class of compounds warrants further study as a therapy for infections with these viruses.
Asunto(s)
Antivirales/farmacología , Antivirales/uso terapéutico , Infecciones por Herpesviridae/tratamiento farmacológico , Herpesviridae/efectos de los fármacos , Nucleósidos de Pirimidina/farmacología , Nucleósidos de Pirimidina/uso terapéutico , Replicación Viral/efectos de los fármacos , Animales , Antivirales/efectos adversos , Antivirales/química , Línea Celular , Proliferación Celular/efectos de los fármacos , Células Cultivadas , ADN Polimerasa Dirigida por ADN/genética , ADN Polimerasa Dirigida por ADN/fisiología , Farmacorresistencia Viral/efectos de los fármacos , Farmacorresistencia Viral/genética , Técnica del Anticuerpo Fluorescente Indirecta , Herpesviridae/genética , Infecciones por Herpesviridae/virología , Herpesvirus Humano 1/efectos de los fármacos , Herpesvirus Humano 1/genética , Herpesvirus Humano 2/efectos de los fármacos , Herpesvirus Humano 2/genética , Herpesvirus Humano 6/efectos de los fármacos , Herpesvirus Humano 6/genética , Herpesvirus Humano 8/efectos de los fármacos , Herpesvirus Humano 8/genética , Humanos , Ratones , Ratones Endogámicos BALB C , Microscopía Fluorescente , Estructura Molecular , Nucleósidos de Pirimidina/síntesis química , Nucleósidos de Pirimidina/química , Proteínas Virales/genética , Proteínas Virales/fisiologíaRESUMEN
The UL97 kinase has been shown to phosphorylate and inactivate the retinoblastoma protein (Rb) and has three consensus Rb-binding motifs that might contribute to this activity. Recombinant viruses containing mutations in the Rb-binding motifs generally replicated well in human foreskin fibroblasts with only a slight delay in replication kinetics. Their susceptibility to the specific UL97 kinase inhibitor, maribavir, was also examined. Mutation of the amino terminal motif, which is involved in the inactivation of Rb, also renders the virus hypersensitive to the drug and suggests that the motif may play a role in its mechanism of action.
Asunto(s)
Bencimidazoles/farmacología , Citomegalovirus/efectos de los fármacos , Citomegalovirus/enzimología , Inhibidores Enzimáticos/farmacología , Fosfotransferasas (Aceptor de Grupo Alcohol)/química , Ribonucleósidos/farmacología , Replicación Viral , Secuencias de Aminoácidos , Línea Celular , Células Cultivadas , Citomegalovirus/genética , Citomegalovirus/fisiología , Humanos , Mutación , Fosfotransferasas (Aceptor de Grupo Alcohol)/genética , Fosfotransferasas (Aceptor de Grupo Alcohol)/metabolismo , Proteína de Retinoblastoma/genética , Proteína de Retinoblastoma/metabolismoRESUMEN
Cells infected with human cytomegalovirus in the absence of UL97 kinase activity produce large nuclear aggregates that sequester considerable quantities of viral proteins. A transient expression assay suggested that pp71 and IE1 were also involved in this process, and this suggestion was significant, since both proteins have been reported to interact with components of promyelocytic leukemia (PML) bodies (ND10) and also interact functionally with retinoblastoma pocket proteins (RB). PML bodies have been linked to the formation of nuclear aggresomes, and colocalization studies suggested that viral proteins were recruited to these structures and that UL97 kinase activity inhibited their formation. Proteins associated with PML bodies were examined by Western blot analysis, and pUL97 appeared to specifically affect the phosphorylation of RB in a kinase-dependent manner. Three consensus RB binding motifs were identified in the UL97 kinase, and recombinant viruses were constructed in which each was mutated to assess a potential role in the phosphorylation of RB and the inhibition of nuclear aggresome formation. The mutation of either the conserved LxCxE RB binding motif or the lysine required for kinase activity impaired the ability of the virus to stabilize and phosphorylate RB. We concluded from these studies that both UL97 kinase activity and the LxCxE RB binding motif are required for the phosphorylation and stabilization of RB in infected cells and that this effect can be antagonized by the antiviral drug maribavir. These data also suggest a potential link between RB function and the formation of aggresomes.