Wednesday, 16 August 2017

Helium ions reveal how viruses attack bacteria

Bacteria and viruses can be imaged with helium ions in contrast to electrons which are the standard workhorse in nanoscale microscopy, report scientists. Helium ions, being more massive than electrons, can be focused to a much tighter spot down to the atomic length scales. By measuring the electrons generated by the ion bombardment, an image can be formed from the sample with biological features visible below the nanometer (one billionth of a meter) length.

The novel technique, called helium ion microscopy (HIM), was used to image hard-to-see interaction between bacteria and viruses infecting bacteria, or so called bacteriophages. These phages are currently actively considered as a novel "smart weapon" against bacterial infections, which are becoming more and more difficult to treat with traditional antibiotics. The images demonstrated in clear images the different stages of how the phages in question attacked the bacteria (E. coli), for example showing the process where the virus has latched onto the bacterial surface, grabbing it with a tentacle like structure, and being in the process of injecting its genome into the bacterial cell.

In addition to imaging, the researchers also demonstrated that the ions can be used as a nanoscale scalpel, to cut portions off individual bacterial cells, or to reveal bacterial colonies under the surfaces of samples. They feel confident that HIM offers many more possibilities in the future to help to study microbes and viruses in their natural state, interacting with each other and other cells.


Miika Leppänen, Lotta-Riina Sundberg, Elina Laanto, Gabriel Magno de Freitas Almeida, Petri Papponen, Ilari J. Maasilta. Imaging Bacterial Colonies and Phage-Bacterium Interaction at Sub-Nanometer Resolution Using Helium-Ion MicroscopyAdvanced Biosystems, 2017; 1700070 DOI: 10.1002/adbi.201700070

Posted by Dr. Tim Sandle