The viral strains used in the process matched themselves to the two partners, and needed the time to build, to control, to form those eggs.

Experts had expected greater differences because viral strains from different locales tend to vary.

Such contamination of viral strains from one dish to another in laboratories is commonplace.

Sometimes, a new viral strain cannot be anticipated, particularly if it originates in animals.

Core proteins are believed to be more stable than those on the surface, which seem to change over time and between viral strains.

I've named it after the viral strain I developed it from.

Something about the structure and arrangement of the viral strain seemed strange to them.

Top health officials swing into action and isolate the new viral strain in laboratories.

Studies comparing the viral strains in the Australian cases have not yet been performed, he said.

Could a new, even more lethal viral strain be leaking into the population?