EVIDENCE THAT NEOMYCIN INHIBITS HUMAN CYTOMEGALOVIRUS-INFECTION OF FIBROBLASTS

The effect of phosphoinositide-binding aminoglycosides, such as neomyc in, gentamicin and streptomycin, on human cytomegalovirus (HCMV) infec tion of human fibroblasts MRC-5 was studied. The inhibition of HCMV in fection was obtained with all of these molecules but neomycin was more effective than the others. We showed that the inoculation of the cell s with cell-free viral suspension in presence of neomycin concentratio ns above 5 mM at 37 degrees C, inhibited more than 98% the HCMV infect ion. However, the preincubation of the fibroblasts with neomycin at 4 degrees C, before the removal of the drug and the inoculation of the c ells, induced only a 30% decrease in the number of infected cells. Add ition of neomycin after the HCMV-binding at 4 degrees C or the infecti on of the cells was less efficient to inhibit HCMV infection than the standard incubation of neomycin during inoculation of the fibroblasts. Indeed, 1 hour after the inoculation of the cells at 37 degrees C, ne omycin still inhibited HCMV infection, but 4 hours after the inoculati on, this drug had no effect on HCMV infection. Our findings demonstrat ed that neomycin must be present at the time of infection in order to exert a full inhibiting effect. The effect of neomycin on the HCMV inf ection was almost immediate upon the addition of the drug (binding and /or internalization) and after the virus internalization (inhibition o f immediate-early events). We suggest that neomycin and other aminogly coside antibiotics may interact with HCMV glycoproteins for binding to similar structural features of cell surface heparan sulfate proteogly cans and may inhibit HCMV infection in fibroblasts by disrupting phosp hoinositide-mediated events in the cells.