Antibody-independent neutralization of vesicular stomatitis virus by human complement. I. Complement requirements.

These studies indicate that neutralization of VSV by normal human serum involves the components of the classical C pathway through C3b and a nonimmunoglobulin serum factor. The reaction is initiated by the direct attachment of C1 to the G protein, which leads to C activation and the sequential deposition of the C components through C3b on the viral envelope. The mechanism of action of the nonimmunoglobulin serum factor remains to be established.