Submitted to: Experimental Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/14/2009
Publication Date: 7/18/2009
Citation: Cao, L., Gong, P., Li, J., Zhang, X., Zou, X., Tuo, W., Liu, Q., Wang, Q., Zhang, G., Chen, L., Li, L., Su, L. 2009. Giardia canis: ultrastructural analysis of G. canis trophozoites transfected with full length G. canis virus cDNA transcripts. Experimental Parasitology. 123:212-217. Interpretive Summary: The present study produced RNA transcripts from the full-length cDNA of the Giardia canis virus, a double-stranded RNA virus of the family Totiviridae and investigated whether these transcripts were infectious to Giardia trophozoites. The data showed that in vitro transcribed Giardia transcripts were fully capable of infecting Giardia trophozoites. The transcripts were apparently replicated, packaged into mature infectious viral particles in the host cells and released from the host parasites. The results suggest that it is possible to manipulate the composition/structure of the Giardia virus for the functional studies of the virus and virus-parasite interactions.
Technical Abstract: Giardia canis virus (GCV) is a double-stranded RNA (dsRNA) virus of the family Totiviridae. In this study, the full-length cDNA of the G. canis virus was constructed in pPoly2/sfinot vector and RNA was transcribed in vitro. Virus-free G. canis trophozoites were transfected with in vitro transcribed GCV RNA by electroporation. Transfected trophozoites were cultured for 12, 24, 36, 48, 60, or 72 h post transfection for analysis. The ultrastructures of the transfected trophozoites were determined by transmission electron microscopy. The viral particles were detectable sporadically in the cytoplasm as early as 24 h post transfection, but became evident and wide-spread 36 h post-transfection. The number of viral particles increased dramatically from 48-60 h. Viral particles were released into the culture medium starting at about 60 h and detectable in nuclei 72 h post transfection. Severe vacuolization was seen in transfected G. canis trophozoites as early as 36 h post transfection and persisted throughout the course of this study. The results of the present study indicate that in vitro transcribed GCV transcripts were capable of infecting Giardia trophozoites, apparently replicated and packaged into mature infectious viral particles which were released from the host.