An official website of the United States government
The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you’re on a federal
government site.
The site is secure.
The https:// ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
Zinkernagel RM, Callahan GN, Althage A, Cooper S, Klein PA, Klein J.Zinkernagel RM, et al.J Exp Med. 1978 Mar 1;147(3):882-96. doi: 10.1084/jem.147.3.882.J Exp Med. 1978.PMID: 305459Free PMC article.