Dr. Kent Brantly donated a gallon or more of his own blood serum to help treat other patients with Ebola. Now, researchers say they’ve used genetically engineered cattle to do something similar. Serum from the cattle has been used to treat hantavirus — a rare but highly deadly virus that causes regular outbreaks, including one that killed three campers at Yosemite National Park in 2012. The same technology might be used against Ebola, MERS and other rare but deadly viruses, the researchers report in the journal Science Translational Medicine. Read more at NBC News…