Giardiavirus Enters Giardia lamblia WB Trophozoite via Endocytosis

doi:10.1006/expr.1993.1019

Experimental Parasitology

Volume 76, Issue 2, March 1993, Pages 165-174

https://doi.org/10.1006/expr.1993.1019 Get rights and content

Abstract

As part of our continuing effort in the study of Giardiavirus life cycle, the early events of Giardia lamblia virus (GLV) infection in the trophozoites of G. lamblia WB strain were examined. Electron microscopy showed that GLV particles were initially localized on plasma membrane. As time progresses, GLV was translocated to the peripheral vacuole and then spread to the cytoplasm. Inhibitors of endocytosis such as sodium azide, chloroquine, or ammonium chloride disrupted viral infection when the drug was added simultaneously with the infecting GLV. The inhibitory effect was reduced when sodium azide or chloroquine was added at various intervals after infection. When cells infected for 1 hr were examined by immunofluorescence staining, sodium azide greatly reduced GLV staining signal in general while chloroquine restricted the staining signal to a few bright spots. Significantly more GLV was found in the peripheral vacuoles of chloroquine-treated cells than untreated controls by semiquantitative electron microscopy. In contrast, only a reduced amount of GLV was found in the peripheral vacuoles of sodium azide-treated cells. These results suggest that sodium azide reduces the internalization of infecting GLV, while chloroquine confines the virus in the peripheral vacuoles and, consequently, leads to nonproductive infection. We conclude from these observations that the entry of GLV into the susceptible WB cells in the event of infection is most likely mediated by endocytosis.

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Cited by (30)

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2020, Encyclopedia of Virology: Volume 1-5, Fourth Edition
The Giardiavirus genus belongs to the Totiviridae family, and comprises the Giardia lamblia virus that infect the protozoa Giardia lamblia. Giardia lamblia virus differs from some other totiviruses by the availability of viral particles in purified and intact form, capable of infecting Giardia cells. The (+)-viral RNA strand is also capable of transfecting Giardia cells to generate viral particles. The virus has thus been turned into a useful agent for genetic transfection, expressing foreign genes or knocking down existing mRNAs in Giardia. Another virus that infects Giardia canis, known as Giardia canis virus (GCV), is closely related to GLV but it has not yet formally classified in the Giardiavirus genus.
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To track whether the ECVs could be endocytic vesicles, endocytic markers, such as Acridine Orange and Lucifer Yellow, were evaluated during the encystation process. Indeed, the PVs are the only known endocytic organelles (Tai et al. 1993) capable of accumulating fluid phase and membrane-bound molecules. However, PVs also seem to have lysosomal properties (Feely and Dyer 1987; Lindmark 1988; McCaffery and Gillin 1994), which means they acidify and mature to become digestive organelles.
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Membrane trafficking and organelle biogenesis in Giardia lamblia: Use it or lose it
2011, International Journal for Parasitology
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In other parasite, Giardia lamblia, other dsRNA virus has been identified, Giardia lamblia virus (GLV) (Wang and Wang, 1986). The time course of GLV infection in G. lamblia reveals that the virus enters susceptible host cells via endocytosis, in which the lysosomal-like peripheral vacuoles serve a translocation ports for the virus to reach the cytoplasm (Tai et al., 1993). In another study, Sepp et al. (1994) proposed that the GLV invasion is most likely mediated by a receptor-directed endocytosis in G. lamblia.
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Regular ArticleGiardiavirus Enters Giardia lamblia WB Trophozoite via Endocytosis

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Giardiavirus Enters Giardia lamblia WB Trophozoite via Endocytosis