Figure 5.

In vitro neutralizing activity in sequential bleedings collected from guinea pigs that received one inoculation of 100 μg of l- and retro-inverso peptides 141–159. Peptides used for inoculation: ▵, l-peptide H-(C)141–159-OH; ◊ and □, l-peptide H-141–159(C)-NH₂ (two animals); • and ⧫, retro-inverso peptide NH₂-(C)141–159-OH (two animals). A neutralizing index of 2.0 logs means that a 1/100 dilution of the antiserum reduces the titer of the homologous virus by 2 log₁₀ units—e.g., from 10⁶ to 10⁴.