Fig. 2.

Compartmentalized antibody responses found in saliva and plasma collaborate in response to the SARS-CoV-2 infection. (A–C) The individual area under the curve (AUC) was plotted as blue or red hollow circles (saliva or plasma, respectively). Bars and whiskers represent median and standard deviation, respectively. Mixed-effect analysis with Tukey’s multiple comparisons test was used to measure statistical significance. *p ≤ 0.05; **p ≤ 0.01; ***p ≤ 0.001; ****p ≤ 0.0001. (D) Five paired immunoglobulins showing significant correlation (p < 0.05) between plasma and saliva were depicted as simple linear regression models. The individual titer of saliva was plotted by paired plasma titers. The predicted regression line and deviations were depicted as a solid and dotted lines, respectively. Functions and p-value of regression analyses were indicated next to the regression lines. Correlations of immunoglobulins specific to the SARS-CoV-2 receptor binding site (RBD) or Spike protein 1 (S1) were colored yellow and red, respectively.