Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
B. pertussis (n = 344) isolates were screened for pertussis toxin (Pt) presence. Signal values for each isolate were normalized to their corresponding positive control and expressed as a fraction of the positive control value. The two Pt-deficient isolates, I979 and J365, were identified as Pt-negative by the assay. Pt-positive control had a ratio = 1, while Pt-negative had a ratio = 0.
