Different sorts of viruses have different weights, but all viruses of a particular type weigh the same amount.

ECONOMIST: Small-scale physics

The H5 in H5N1 stands for hemagglutinin type 5, meaning the fifth known type of hemagglutinin found on the coatings of influenza viruses.

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Meanwhile, Jillian Shapiro of Mount Sinai Medical School figured out away to get another new type of genetic material, called microRNA, into cells using viruses.

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