- N-terminal amino acid “signal sequences” for factor H binding protein (fHbp) 1.1 transgenes encoded by human adenovirus serotype 5 viral vector vaccines. The signal peptide portion of the sequence is highlighted in red, the LTA portion of the lipobox in green, the lipobox cysteine in blue, the N-terminal methionine in purple, and the SSG amino acids that remains following the natural cleavage of the signal peptide in black. KO, knockout.