Could the FC vaccine sera inhibit infectivity of pseudotyped HIV virions bearing an amphotropic murine leukemia virus (MLV) envelope protein or a PI of the simian immunodeficiency virus SIVmac251?

What would be a reason for doing this crucial control experiment?
Answer Despite the apparent requirement for fusion competency in the immunogen, the researchers wanted to exclude the possibility that FC vaccine sera inhibited viral infectivity in a nonspecific manner.

RESULTS:

Symbols: FC immunogen (black squares) and FI immunogen (COS-env + U87 cells, gray circles).

Interpretation of these results

Did the FC vaccine sera inhibit the infectivity of pseudotyped HIV virions bearing an amphotropic murine leukemia virus (MLV) envelope protein?
Answer No

Did the FC vaccine sera inhibit the infectivity of a PI of the simian immunodeficiency virus SIVmac251?
Answer No

What do these results imply?
Answer that the effective antibodies were binding to structures conserved among HIV-1 envelope glycoproteins but not shared by SIV and MLV.

What would be the implication if the opposite results occurred, showing SIV and MLV had been neutralized?
Answer Significant questions would have been raised about just what the antibodies were actually reacting with!

NEXT QUESTION TO PONDER:

Could FC and FI vaccines elicit neutralization of a related laboratory-adapted isolate of HIV, the T cell line-adapted derivative of 168P, 168C? Click here to find out!

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