Restriction of vaccinia virus replication by a ced-3 and ced-4 -dependent pathway in Caenorhabditis elegans

Abstract

Genetic tractability and easy manipulation make Caenorhabditis elegans a good model to study host-pathogen interactions. Dozens of different bacterial species can pathogenically infect C. elegans under laboratory conditions, and all of these microbes are extracellular pathogens to nematodes. Viruses, on the other hand, are obligate intracellular parasites, and yet no viral infections have been reported for C. elegans. We established a procedure allowing vaccinia virus to enter and subsequently replicate in C. elegans. Virus replication was significantly enhanced in ced-3, ced-4, ced-9(gf), and egl-1(lf) mutants, demonstrating that the core programmed cell death (PCD) genes ced-3, ced-4, ced-9, and egl-1 control vaccinia virus replication in C. elegans. The ability of ced-3 and ced-4 alleles to restrict virus replication is correlated with their cell-killing activities. Moreover, the increase in vaccinia virus replication levels in the PCD-defective mutants was not likely to be caused by the extra live cells, as neither the inhibition of PCD by icd-1 overexpression nor the presence of extra cells after extra cell divisions in cul-1 or lin-23 mutants had any significant effect on vaccinia virus replication. Therefore, the core PCD genes possess a unique function in controlling vaccinia virus replication in C. elegans.programmed cell death ͉ virus-host interaction

A C. elegans-based foam for rapid on-site detection of residual live virus.

“…Vero/HEK Low serum, 48 hr, non-purified *4% DMSO has been reported to facilitate assembly of viral particles (Scholtissek and Muller, 1988) Note that although polyethylene glycol (PEG) was reported to increase C. elegans susceptibility to viral infection (Liu et al, 2006, PNAS, 103:4174), we did not observe any differene in infection efficiency of rVSV-GFP in C. elegans exposed to different PEG molecular weights and concentrations.…”

“…C. elegans, a non-parasitic nematode maintained in the laboratory under BSL-1 containment (Stiernagle, 2006), is an accepted model for studying eukaryotic host responses to viruses (Lu et Liu et al 2006). The relative genetic simplicity of worms, the availability of an extensive collection of mutants, the ease of conducting random mutagenesis screens, enabling the isolation of gain-of-function as well as loss-of-function mutations, and the detailed genetic and physical maps enabling the straightforward identification of mutant genes makes the worm an attractive host for characterizing viral infectivity.…”

Microbial Interactions with Caenorhabditis elegans: Lessons from a Model Organism

“…In fact, this organism was not considered an appropriate model organism for studying virus-host interactions. Previous efforts to define virus-host responses in C. elegans were pursued by several independent groups who, using artificial techniques of introducing viruses into animals, where able to demonstrate that viruses that infect mammalian cells can indeed infect, replicate, and assemble within C. elegans cells (Liu et al 2006;Lu et al 2005;Schott et al 2005;Wilkins et al 2005). Wilkins et al and Schott et al were able to show that cultured primary cells from C. elegans embryos could be infected with vesicular stomatitis virus (VSV), a negative-strand RNA virus that infects both insects and mammals.…”

Caenorhabditis elegans as an Emerging Model for Virus-Host Interactions

“…Studies of these predominantly extracellular pathogens have largely shaped our understanding of C. elegans immunity. However, with the recent discovery of natural intracellular pathogens of C. elegans (12,13) and the development of nonnatural virus infection models (14)(15)(16)(17)(18), this is beginning to change.…”

“…1). For brevity, the most prominent RNA virus models are discussed, although it should be noted that a DNA virus model using the poxvirus vaccinia virus was also reported in C. elegans (18).…”