Researchers have tracked down two Zika proteins potentially responsible for thousands of microcephaly cases in Brazil and elsewhere -- taking one small step toward preventing Zika-infected mothers from birthing babies with abnormally small heads. The Zika virus contains 10 proteins, but only NS4A and NS4B matter when it comes to microcephaly. These miscreant proteins, researchers discovered, have two shared life goals: to handicap fetal brain formation and to mobilize their malevolent forces.