RETROVIRUS BUDDING MAY CONSTITUTE A PORT OF ENTRY FOR DRUG CARRIERS

This paper investigates the relation between viral infection and cell uptake of liposomes and nanoparticles. A defective virus was used to i nfect two types of cells: cells allowing virus budding (psi2neo cells) and cells bereft of a virus exit process (NIH 3T3 cells). This study has revealed that cell uptake of pH-sensitive-liposomes is highly depe ndent on the virus exit process, since it ensued only when virus buddi ng occurred. This preferential uptake of pH-sensitive liposomes by inf ected cells was not carrier-specific because similar uptake was observ ed with non-biodegradable fluorescent nanoparticles using confocal mic roscopy. Also, inhibition of neo gene expression by oligonucleotide pH -sensitive-liposomes was only observed in the cell system (psi2neo) en dowed with a virus exit process. Finally, increased membrane fluidity was noted in the infected cells, possibly reflecting membrane perturba tion due to virus budding. We suggest that this membrane perturbation may be the key to the uptake of the different colloidal carriers. Infe cted cells could, thus, constitute a natural target for particulate dr ug carriers.