Figure 6

Effect of antibodies on pathogen infection and gene expression. (A) B. bigemina DNA levels were determined by real-time PCR in ticks capillary-fed on B. bigemina-infected blood without (Blood) and with preimmune and anti-tick protein IgGs (TROSPA, SILK and Subolesin). The DNA levels were normalized against tick 16S rDNA, shown as Ave + S.D. normalized Ct values (arbitrary units) and compared between the group with preimmune antibodies and the other groups by Student’s t-Test (P > 0.05; N = 10). (B) A. marginale DNA levels were determined by real-time PCR in ticks capillary-fed on A. marginale-infected blood without (Blood) and with preimmune and anti-tick protein IgGs. The DNA levels were normalized against tick 16S rDNA, shown as Ave + S.D. normalized Ct values (arbitrary units) and compared between the group with preimmune antibodies and the other groups by Student’s t-Test (P > 0.05; N = 10). (C) Effect of A. marginale and B. bigemina infection on gene expression. The mRNA levels of genes encoding for tick proteins trospa, silk and sub were characterized by real-time RT-PCR in ticks capillary-fed on uninfected and infected blood. The mRNA levels were normalized against tick 16S rRNA, shown as the Ave + S.D. infected/uninfected blood Ct ratio (arbitrary units) and compared between ticks fed on infected and uninfected blood by Student’s t-Test (P > 0.05; N = 10). (D) Effect of anti-SUB antibodies on sub gene expression. The sub mRNA levels were characterized by real-time RT-PCR in ticks capillary-fed on uninfected blood alone or with the addition of preimmune or anti-SUB IgGs. The mRNA levels were normalized against tick 16S rRNA, shown as Ave + S.D. normalized Ct values (arbitrary units) and compared between groups by Student’s t-Test (*p ≤ 0.05; N = 10).