Susceptibilities of Human Cytomegalovirus Clinical Isolates to BAY38-4766, BAY43-9695, and Ganciclovir

Abstract

BAY38-4766 and BAY43-9695 are nonnucleosidic compounds with activities against human cytomegalovirus (HCMV). Two phenotypic assays were used to determine the drug susceptibilities of 36 HCMV clinical isolates to the BAY compounds and ganciclovir. Using either assay, both BAY compounds at a concentration of approximately 1 M inhibited the replication of all 36 HCMV clinical isolates, including 11 ganciclovirresistant clinical isolates, by 50%.Human cytomegalovirus (HCMV) causes considerable morbidity and mortality in immunocompromised hosts (13). Organ transplant patients suffer from hepatitis and pneumonia caused by HCMV infections, whereas AIDS patients suffer from HCMV-induced retinitis and other complications (1). The current Food and Drug Administration-approved therapies for retinitis due to infection with HCMV include ganciclovir, foscarnet, cidofovir, and fomivirsen (2,11,12,14). These antiviral drugs are active against infections caused by HCMV; however, they are not ideal because of their toxicity and poor bioavailability. Furthermore, long-term treatment with these antiviral agents often leads to the selection of viral mutants that are resistant to one or more of these drugs (3-5). Current research has led to the discovery of several novel compounds with in vitro and in vivo activities against HCMV (6, 7, 16). One such compound, BAY38-4766, is a nonnucleosidic inhibitor of HCMV replication (17). Two phenotypic drug susceptibility assays, a flow cytometric fluorescence-activated cell sorter (FACS) assay (8-10) and a plaque reduction assay (PRA) (15), were used to compare the effects of BAY38-4766, its main metabolite, BAY43-9695, and ganciclovir on the in vitro replication of ganciclovir-susceptible and ganciclovir-resistant HCMV clinical isolates. BAY38-4766 and BAY43-9695 inhibited the replication of ganciclovir-sensitive and ganciclovirresistant HCMV clinical isolates at concentrations less than or equal to 1 M. These results suggest that these compounds are potentially useful for treating patients infected with ganciclovir-sensitive or ganciclovir-resistant HCMV.The use of the FACS assay and the PRA for determining 50% inhibitory concentrations (IC 50 s) for HCMV clinical isolates have been described in detail previously (8-10). These two phenotypic assays were used to determine the susceptibilities of the AD169 laboratory strain of HCMV and 36 HCMV clinical isolates to BAY38-4766, BAY43-9695, and ganciclovir. The FACS assay yielded average IC 50 s of BAY38-4766, BAY43-9695, and ganciclovir for the AD169 laboratory strain of 0.95 Ϯ 0.17 (mean Ϯ standard deviation), 0.70 Ϯ 0.30, and 3.05 Ϯ 0.21 M, respectively. The PRA yielded average IC 50 s of these three drugs for AD169 of 0.64 Ϯ 0.14, 0.55 Ϯ 0.06, and 3.50 Ϯ 0.21 M, respectively. The average IC 50 s of the two BAY compounds and ganciclovir for 36 HCMV clinical isolates are presented in Table 1. Both BAY compounds inhibited the replication of all of the HCMV clinical isolates by 50% at essentially the same concentrations. Of the 36 HCMV clinical i...

Human Cytomegalovirus Resistance to Antiviral Drugs

“…Other promising compounds include another derivative of the prototype compound BDCRB, the D-ribopyranosyl derivative GW275175X (GlaxoSmithKline), as well as the nonnucleosidic 4-sulfonamide-substituted naphthalene derivative tomeglovir (BAY-384766; Bayer). Both compounds showed good inhibitory activities against HCMV replication (92,111,127) and seem to interfere with cleavage of concatameric DNA molecules and encapsidation, which involve pUL89 and pUL56, respectively (24,127).…”

Phenotypic Drug Susceptibility Assay for Influenza Virus Neuraminidase Inhibitors

“…The effect of antiviral compounds on the replication of influenza viruses in MDCK cells was determined by flow cytometric analysis of virus-infected cells. The procedure was essentially as described previously with the following modifications (8,(34)(35)(36)(37). Briefly, 2-day-old confluent MDCK cell monolayers in 25-cm 2 flasks were washed twice with MEM supplemented with 0.2% BSA and infected with influenza virus at an MOI of 0.001 PFU per cell in 1 ml of virus growth medium supplemented with various concentrations of antiviral compounds.…”

“…The FACS assay is rapid and quantitative. For herpes simplex viruses and human cytomegalovirus, the EC 50 values (the concentrations of drug that reduce the number of virus-infected cells by 50%) obtained by FACS analysis correlate with those obtained with the virus yield reduction assay and the PRA (8,(35)(36)(37). In this proof-of-principle report, we show that fluorochrome-labeled monoclonal antibodies to influenza virus type A or type B nucleocapsid antigens and FACS analysis can be used to determine the in vitro drug susceptibilities of influenza virus laboratory strains and clinical isolates to the NA inhibitors peramivir, zanamivir, oseltamivir carboxylate, and ribavirin. )…”

Non‐nucleoside inhibitors of herpesviruses

“…The leading candidate from this research effort is BAY 38-4766 (Figure 3). BAY 38-4766 is reported to have approximately 5-fold greater antiviral cell culture activity than ganciclovir against clinical isolates of HCMV (IC 50 of 1.2 mM vs 5.8 mM for 8 isolates tested) [44]. In addition, BAY 38-4766 displayed excellent antiviral activity against several animal CMVs such as murine CMV, rat CMV and rhesus CMV.…”