In a paper published in Nature Structural & Molecular Biology, the scientists of Purdue University have mapped the evolution of Zika virus in two distinct phases using a technique called cryo-electron microscopy. It is understood that the virus particles form bridges to the surrounding membrane layers. As the virus particles reshuffle, the bridges disappear effectively clearing the path for propagation.

This is a significant development in understanding Zika virus as this the first instance scientists have seen such rearrangement in the core of a flavivirus. Dengue, west Nile and yellow fever are part of the flavivirus group which is also expected to exhibit similar traits during their evolution.

The researchers believe the reshuffling helps the Zika virus become infectious and also contemplate if blocking reorganization could stall the virus from becoming infectious. The image contains three-headed protein spikes and the layers outside the membrane (aqua) that encloses the core. Outside the membrane, it easy to identify the surface protein called envelope along with proteins that help the virus enter the cells.

Cryo-electron microscopy is a type of transmission electron microscopy where the sample is studied at cryogenic temperatures and is mainly used in structural biology. Significantly, the technique allows observation of cellular components that are not stained anyway, unlike X-ray crystallography that requires crystallizing specimen. Crystallization can occasionally lead to irrelevant and irreversible conformational changes in the cellular components.

The Zika virus is mainly a mosquito-borne illness and is largely associated with fetal birth defect microcephaly. The condition results in brain damage and abnormally small head born to mothers infected during pregnancy. In addition, the virus is also found to cause autoimmune disorder Guillain-Barré syndrome which leads to paralysis.

The Nature Structural & Molecular Biology paper was authored by Mangala Prasad; staff scientist Andrew S. Miller; assistant research scientist Thomas Klose; former doctoral student Devika Sirohi; laboratory manager Geeta Buda; Wen Jiang, a professor of biological sciences and chemistry; Kuhn; and Rossmann.