Clathrin-independent entry of baculovirus triggers uptake of E. coli in non-phagocytic human cells

• Published in: PloS one Vol. 4; no. 4; p. e5093
• Main Authors: Laakkonen, Johanna P, Mäkelä, Anna R, Kakkonen, Elina, Turkki, Paula, Kukkonen, Sari, Peränen, Johan, Ylä-Herttuala, Seppo, Airenne, Kari J, Oker-Blom, Christian, Vihinen-Ranta, Maija, Marjomäki, Varpu
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 07.04.2009; Public Library of Science (PLoS)
• Subjects: Adenosine Triphosphatases - physiology; ADP-Ribosylation Factors - physiology; Autographa californica; Bacteria; Baculovirus; Base Sequence; Biochemistry/Cell Signaling and Trafficking Structures; Biotechnology; Cancer; Cell Biology/Membranes and Sorting; Cell Line; Cells (Biology); Clathrin; Clathrin - physiology; Discosoma; E coli; Endocytosis; Environmental science; Escherichia coli; Escherichia coli - physiology; Fluorescence; Gene expression; Gene therapy; Gene transfer; Genetic vectors; Heparan sulfate; Herpes viruses; Humans; Insects; Internalization; Membrane Lipids - metabolism; Microscopy; Mutants; Nuclear polyhedrosis virus; Nucleopolyhedrovirus - physiology; Pathogenesis; Phagocytes; Phagocytosis; Proteins; Rac1 protein; Regulators; RhoA protein; RNA Interference; Rodents; Shigellosis; Trends; Virology; Viruses; Finland
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0005093

The prototype baculovirus, Autographa californica multiple nucleopolyhedrovirus, an insect pathogen, holds great potential as a gene therapy vector. To develop transductional targeting and gene delivery by baculovirus, we focused on characterizing the nature and regulation of its uptake in human cancer cells. Baculovirus entered the cells along fluid-phase markers from the raft areas into smooth-surfaced vesicles devoid of clathrin. Notably, regulators associated with macropinocytosis, namely EIPA, Pak1, Rab34, and Rac1, had no significant effect on viral transduction, and the virus did not induce fluid-phase uptake. The internalization and nuclear uptake was, however, affected by mutants of RhoA, and of Arf6, a regulator of clathrin-independent entry. Furthermore, the entry of baculovirus induced ruffle formation and triggered the uptake of fluorescent E. coli bioparticles. To conclude, baculovirus enters human cells via a clathrin-independent pathway, which is able to trigger bacterial uptake. This study increases our understanding of virus entry strategies and gives new insight into baculovirus-mediated gene delivery in human cells.