Tunneling Nanotube-like Structures in Giardia duodenalis

<i>Giardia doudenalis</i> (<i>lamblia</i>, <i>intestinalis</i>) is a protozoan parasite that inhabits the lumen of the upper small intestine of vertebrates, causing chronic abdominal pains and severe diarrhea, symptoms of giardiasis, a persistent and recurrent infection. This characteristic is mainly due to the presence of membrane variant-specific surface proteins (VSPs) that give this parasite the ability to successively infect the host through antigenic variation. Using high-resolution scanning microscopy (HR-SM), we observed the presence, formation, and extension of tunneling-nanotube-like surface structures in <i>Giardia</i>, especially following parasite challenges with VSP antibodies. They were seen all over the parasite surface, both <i>in vitro</i> and <i>in vivo</i>, showing that <i>G</i>. <i>duodenalis</i> nanotube formation occurs in complex environments such as the gut. In addition, we also observed that some of these nanotubes displayed a periodic strangulation that produces 100 nm vesicles that seemed to be released in a process similar to that previously observed in <i>Trypanosoma brucei.</i> The presence of nanotube-like structures in <i>G. duodenalis</i> highlights yet another strategy of cellular communication utilized by these parasites, whether between themselves or with the host cell.