Different mechanisms of cell entry by human-pathogenic Old World and New World arenaviruses.
The Old World arenavirus Lassa virus (LASV) is the causative agent of severe viral hemorrhagic fever (VHF) in humans and is the most prevalent human pathogen among arenaviruses. The present study investigated the largely unknown mechanisms of cell entry of LASV, a process know to be mediated solely by the virus envelope glycoprotein (GP). To circumvent biosafety restrictions associated with the use of live LASV, we used reverse genetics to generate a recombinant variant of the prototypic arenavirus lymphocytic choriomeningitis virus (LCMV) expressing the LASV GP (rLCMV-LASVGP). The rescued rLCMV-LASVGP grew to titers comparable to that of LCMV and showed the receptor binding characteristics of LASV. We used rLCMV-LASVGP to characterize the cellular mechanisms of LASV entry in the context of a productive arenavirus infection. The kinetics of pH-dependent membrane fusion of rLCMV-LASVGP resembled those of the human-pathogenic New World arenavirus Junin virus (JUNV) and other enveloped viruses that use clathrin-mediated endocytosis for entry. However, rLCMV-LASVGP entered cells predominantly via a clathrin-, caveolin-, and dynamin-independent endocytotic pathway similar to the one recently described for LCMV. Productive infection of rLCMV-LASVGP was only mildly affected by a dominant negative mutant of Rab5 and was independent of Rab7, suggesting an unusual mechanism of delivery to endosomes. In addition, rLCMV-LASVGP infection was independent of actin but required intact microtubules. Our data indicate that LASV enters cells via a pathway distinct from the one used by human-pathogenic New World arenaviruses.
Viral Immunobiology Laboratory, Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California 92037, USA.
Jillian M
JM
Rojek
Ana B
AB
Sanchez
Ngoc Thao
NT
Nguyen
Juan-Carlos
JC
de la Torre
Stefan
S
Kunz
D000199:Actins / Q000235:genetics; D000818:Animals; D006477:Arenaviruses, New World / Q000502:physiology; D018049:Arenaviruses, Old World / Q000502:physiology*; D002460:Cell Line; D002522:Chlorocebus aethiops; D006224:Cricetinae; D004705:Endocytosis; D011992:Endosomes / Q000821:virology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007836:Lassa virus / Q000235:genetics*; D008217:Lymphocytic choriomeningitis virus / Q000235:genetics*; D008870:Microtubules / Q000821:virology; D013997:Time Factors; D053586:Virus Internalization; D020691:rab GTP-Binding Proteins / Q000235:genetics; D020696:rab5 GTP-Binding Proteins / Q000235:genetics; D000090802:rab7 GTP-Binding Proteins
D000199:Actins; D000090802:rab7 GTP-Binding Proteins; C000716463:rab7 GTP-binding proteins, human; D020691:rab GTP-Binding Proteins; D020696:rab5 GTP-Binding Proteins